Adding upstream version 14.5.upstream/14.5upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2720 insertions, 0 deletions

diff --git a/src/include/nodes/pathnodes.h b/src/include/nodes/pathnodes.h
new file mode 100644
index 0000000..f16466a
--- /dev/null
+++ b/src/include/nodes/pathnodes.h
@@ -0,0 +1,2720 @@
+/*-------------------------------------------------------------------------
+ *
+ * pathnodes.h
+ *	  Definitions for planner's internal data structures, especially Paths.
+ *
+ *
+ * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/nodes/pathnodes.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef PATHNODES_H
+#define PATHNODES_H
+
+#include "access/sdir.h"
+#include "lib/stringinfo.h"
+#include "nodes/params.h"
+#include "nodes/parsenodes.h"
+#include "storage/block.h"
+
+
+/*
+ * Relids
+ *		Set of relation identifiers (indexes into the rangetable).
+ */
+typedef Bitmapset *Relids;
+
+/*
+ * When looking for a "cheapest path", this enum specifies whether we want
+ * cheapest startup cost or cheapest total cost.
+ */
+typedef enum CostSelector
+{
+	STARTUP_COST, TOTAL_COST
+} CostSelector;
+
+/*
+ * The cost estimate produced by cost_qual_eval() includes both a one-time
+ * (startup) cost, and a per-tuple cost.
+ */
+typedef struct QualCost
+{
+	Cost		startup;		/* one-time cost */
+	Cost		per_tuple;		/* per-evaluation cost */
+} QualCost;
+
+/*
+ * Costing aggregate function execution requires these statistics about
+ * the aggregates to be executed by a given Agg node.  Note that the costs
+ * include the execution costs of the aggregates' argument expressions as
+ * well as the aggregate functions themselves.  Also, the fields must be
+ * defined so that initializing the struct to zeroes with memset is correct.
+ */
+typedef struct AggClauseCosts
+{
+	QualCost	transCost;		/* total per-input-row execution costs */
+	QualCost	finalCost;		/* total per-aggregated-row costs */
+	Size		transitionSpace;	/* space for pass-by-ref transition data */
+} AggClauseCosts;
+
+/*
+ * This enum identifies the different types of "upper" (post-scan/join)
+ * relations that we might deal with during planning.
+ */
+typedef enum UpperRelationKind
+{
+	UPPERREL_SETOP,				/* result of UNION/INTERSECT/EXCEPT, if any */
+	UPPERREL_PARTIAL_GROUP_AGG, /* result of partial grouping/aggregation, if
+								 * any */
+	UPPERREL_GROUP_AGG,			/* result of grouping/aggregation, if any */
+	UPPERREL_WINDOW,			/* result of window functions, if any */
+	UPPERREL_DISTINCT,			/* result of "SELECT DISTINCT", if any */
+	UPPERREL_ORDERED,			/* result of ORDER BY, if any */
+	UPPERREL_FINAL				/* result of any remaining top-level actions */
+	/* NB: UPPERREL_FINAL must be last enum entry; it's used to size arrays */
+} UpperRelationKind;
+
+/*----------
+ * PlannerGlobal
+ *		Global information for planning/optimization
+ *
+ * PlannerGlobal holds state for an entire planner invocation; this state
+ * is shared across all levels of sub-Queries that exist in the command being
+ * planned.
+ *----------
+ */
+typedef struct PlannerGlobal
+{
+	NodeTag		type;
+
+	ParamListInfo boundParams;	/* Param values provided to planner() */
+
+	List	   *subplans;		/* Plans for SubPlan nodes */
+
+	List	   *subroots;		/* PlannerInfos for SubPlan nodes */
+
+	Bitmapset  *rewindPlanIDs;	/* indices of subplans that require REWIND */
+
+	List	   *finalrtable;	/* "flat" rangetable for executor */
+
+	List	   *finalrowmarks;	/* "flat" list of PlanRowMarks */
+
+	List	   *resultRelations;	/* "flat" list of integer RT indexes */
+
+	List	   *appendRelations;	/* "flat" list of AppendRelInfos */
+
+	List	   *relationOids;	/* OIDs of relations the plan depends on */
+
+	List	   *invalItems;		/* other dependencies, as PlanInvalItems */
+
+	List	   *paramExecTypes; /* type OIDs for PARAM_EXEC Params */
+
+	Index		lastPHId;		/* highest PlaceHolderVar ID assigned */
+
+	Index		lastRowMarkId;	/* highest PlanRowMark ID assigned */
+
+	int			lastPlanNodeId; /* highest plan node ID assigned */
+
+	bool		transientPlan;	/* redo plan when TransactionXmin changes? */
+
+	bool		dependsOnRole;	/* is plan specific to current role? */
+
+	bool		parallelModeOK; /* parallel mode potentially OK? */
+
+	bool		parallelModeNeeded; /* parallel mode actually required? */
+
+	char		maxParallelHazard;	/* worst PROPARALLEL hazard level */
+
+	PartitionDirectory partition_directory; /* partition descriptors */
+} PlannerGlobal;
+
+/* macro for fetching the Plan associated with a SubPlan node */
+#define planner_subplan_get_plan(root, subplan) \
+	((Plan *) list_nth((root)->glob->subplans, (subplan)->plan_id - 1))
+
+
+/*----------
+ * PlannerInfo
+ *		Per-query information for planning/optimization
+ *
+ * This struct is conventionally called "root" in all the planner routines.
+ * It holds links to all of the planner's working state, in addition to the
+ * original Query.  Note that at present the planner extensively modifies
+ * the passed-in Query data structure; someday that should stop.
+ *
+ * For reasons explained in optimizer/optimizer.h, we define the typedef
+ * either here or in that header, whichever is read first.
+ *----------
+ */
+#ifndef HAVE_PLANNERINFO_TYPEDEF
+typedef struct PlannerInfo PlannerInfo;
+#define HAVE_PLANNERINFO_TYPEDEF 1
+#endif
+
+struct PlannerInfo
+{
+	NodeTag		type;
+
+	Query	   *parse;			/* the Query being planned */
+
+	PlannerGlobal *glob;		/* global info for current planner run */
+
+	Index		query_level;	/* 1 at the outermost Query */
+
+	PlannerInfo *parent_root;	/* NULL at outermost Query */
+
+	/*
+	 * plan_params contains the expressions that this query level needs to
+	 * make available to a lower query level that is currently being planned.
+	 * outer_params contains the paramIds of PARAM_EXEC Params that outer
+	 * query levels will make available to this query level.
+	 */
+	List	   *plan_params;	/* list of PlannerParamItems, see below */
+	Bitmapset  *outer_params;
+
+	/*
+	 * simple_rel_array holds pointers to "base rels" and "other rels" (see
+	 * comments for RelOptInfo for more info).  It is indexed by rangetable
+	 * index (so entry 0 is always wasted).  Entries can be NULL when an RTE
+	 * does not correspond to a base relation, such as a join RTE or an
+	 * unreferenced view RTE; or if the RelOptInfo hasn't been made yet.
+	 */
+	struct RelOptInfo **simple_rel_array;	/* All 1-rel RelOptInfos */
+	int			simple_rel_array_size;	/* allocated size of array */
+
+	/*
+	 * simple_rte_array is the same length as simple_rel_array and holds
+	 * pointers to the associated rangetable entries.  Using this is a shade
+	 * faster than using rt_fetch(), mostly due to fewer indirections.
+	 */
+	RangeTblEntry **simple_rte_array;	/* rangetable as an array */
+
+	/*
+	 * append_rel_array is the same length as the above arrays, and holds
+	 * pointers to the corresponding AppendRelInfo entry indexed by
+	 * child_relid, or NULL if the rel is not an appendrel child.  The array
+	 * itself is not allocated if append_rel_list is empty.
+	 */
+	struct AppendRelInfo **append_rel_array;
+
+	/*
+	 * all_baserels is a Relids set of all base relids (but not "other"
+	 * relids) in the query; that is, the Relids identifier of the final join
+	 * we need to form.  This is computed in make_one_rel, just before we
+	 * start making Paths.
+	 */
+	Relids		all_baserels;
+
+	/*
+	 * nullable_baserels is a Relids set of base relids that are nullable by
+	 * some outer join in the jointree; these are rels that are potentially
+	 * nullable below the WHERE clause, SELECT targetlist, etc.  This is
+	 * computed in deconstruct_jointree.
+	 */
+	Relids		nullable_baserels;
+
+	/*
+	 * join_rel_list is a list of all join-relation RelOptInfos we have
+	 * considered in this planning run.  For small problems we just scan the
+	 * list to do lookups, but when there are many join relations we build a
+	 * hash table for faster lookups.  The hash table is present and valid
+	 * when join_rel_hash is not NULL.  Note that we still maintain the list
+	 * even when using the hash table for lookups; this simplifies life for
+	 * GEQO.
+	 */
+	List	   *join_rel_list;	/* list of join-relation RelOptInfos */
+	struct HTAB *join_rel_hash; /* optional hashtable for join relations */
+
+	/*
+	 * When doing a dynamic-programming-style join search, join_rel_level[k]
+	 * is a list of all join-relation RelOptInfos of level k, and
+	 * join_cur_level is the current level.  New join-relation RelOptInfos are
+	 * automatically added to the join_rel_level[join_cur_level] list.
+	 * join_rel_level is NULL if not in use.
+	 */
+	List	  **join_rel_level; /* lists of join-relation RelOptInfos */
+	int			join_cur_level; /* index of list being extended */
+
+	List	   *init_plans;		/* init SubPlans for query */
+
+	List	   *cte_plan_ids;	/* per-CTE-item list of subplan IDs (or -1 if
+								 * no subplan was made for that CTE) */
+
+	List	   *multiexpr_params;	/* List of Lists of Params for MULTIEXPR
+									 * subquery outputs */
+
+	List	   *eq_classes;		/* list of active EquivalenceClasses */
+
+	bool		ec_merging_done;	/* set true once ECs are canonical */
+
+	List	   *canon_pathkeys; /* list of "canonical" PathKeys */
+
+	List	   *left_join_clauses;	/* list of RestrictInfos for mergejoinable
+									 * outer join clauses w/nonnullable var on
+									 * left */
+
+	List	   *right_join_clauses; /* list of RestrictInfos for mergejoinable
+									 * outer join clauses w/nonnullable var on
+									 * right */
+
+	List	   *full_join_clauses;	/* list of RestrictInfos for mergejoinable
+									 * full join clauses */
+
+	List	   *join_info_list; /* list of SpecialJoinInfos */
+
+	/*
+	 * all_result_relids is empty for SELECT, otherwise it contains at least
+	 * parse->resultRelation.  For UPDATE/DELETE across an inheritance or
+	 * partitioning tree, the result rel's child relids are added.  When using
+	 * multi-level partitioning, intermediate partitioned rels are included.
+	 * leaf_result_relids is similar except that only actual result tables,
+	 * not partitioned tables, are included in it.
+	 */
+	Relids		all_result_relids;	/* set of all result relids */
+	Relids		leaf_result_relids; /* set of all leaf relids */
+
+	/*
+	 * Note: for AppendRelInfos describing partitions of a partitioned table,
+	 * we guarantee that partitions that come earlier in the partitioned
+	 * table's PartitionDesc will appear earlier in append_rel_list.
+	 */
+	List	   *append_rel_list;	/* list of AppendRelInfos */
+
+	List	   *row_identity_vars;	/* list of RowIdentityVarInfos */
+
+	List	   *rowMarks;		/* list of PlanRowMarks */
+
+	List	   *placeholder_list;	/* list of PlaceHolderInfos */
+
+	List	   *fkey_list;		/* list of ForeignKeyOptInfos */
+
+	List	   *query_pathkeys; /* desired pathkeys for query_planner() */
+
+	List	   *group_pathkeys; /* groupClause pathkeys, if any */
+	List	   *window_pathkeys;	/* pathkeys of bottom window, if any */
+	List	   *distinct_pathkeys;	/* distinctClause pathkeys, if any */
+	List	   *sort_pathkeys;	/* sortClause pathkeys, if any */
+
+	List	   *part_schemes;	/* Canonicalised partition schemes used in the
+								 * query. */
+
+	List	   *initial_rels;	/* RelOptInfos we are now trying to join */
+
+	/* Use fetch_upper_rel() to get any particular upper rel */
+	List	   *upper_rels[UPPERREL_FINAL + 1]; /* upper-rel RelOptInfos */
+
+	/* Result tlists chosen by grouping_planner for upper-stage processing */
+	struct PathTarget *upper_targets[UPPERREL_FINAL + 1];
+
+	/*
+	 * The fully-processed targetlist is kept here.  It differs from
+	 * parse->targetList in that (for INSERT) it's been reordered to match the
+	 * target table, and defaults have been filled in.  Also, additional
+	 * resjunk targets may be present.  preprocess_targetlist() does most of
+	 * that work, but note that more resjunk targets can get added during
+	 * appendrel expansion.  (Hence, upper_targets mustn't get set up till
+	 * after that.)
+	 */
+	List	   *processed_tlist;
+
+	/*
+	 * For UPDATE, this list contains the target table's attribute numbers to
+	 * which the first N entries of processed_tlist are to be assigned.  (Any
+	 * additional entries in processed_tlist must be resjunk.)  DO NOT use the
+	 * resnos in processed_tlist to identify the UPDATE target columns.
+	 */
+	List	   *update_colnos;
+
+	/* Fields filled during create_plan() for use in setrefs.c */
+	AttrNumber *grouping_map;	/* for GroupingFunc fixup */
+	List	   *minmax_aggs;	/* List of MinMaxAggInfos */
+
+	MemoryContext planner_cxt;	/* context holding PlannerInfo */
+
+	double		total_table_pages;	/* # of pages in all non-dummy tables of
+									 * query */
+
+	double		tuple_fraction; /* tuple_fraction passed to query_planner */
+	double		limit_tuples;	/* limit_tuples passed to query_planner */
+
+	Index		qual_security_level;	/* minimum security_level for quals */
+	/* Note: qual_security_level is zero if there are no securityQuals */
+
+	bool		hasJoinRTEs;	/* true if any RTEs are RTE_JOIN kind */
+	bool		hasLateralRTEs; /* true if any RTEs are marked LATERAL */
+	bool		hasHavingQual;	/* true if havingQual was non-null */
+	bool		hasPseudoConstantQuals; /* true if any RestrictInfo has
+										 * pseudoconstant = true */
+	bool		hasAlternativeSubPlans; /* true if we've made any of those */
+	bool		hasRecursion;	/* true if planning a recursive WITH item */
+
+	/*
+	 * Information about aggregates. Filled by preprocess_aggrefs().
+	 */
+	List	   *agginfos;		/* AggInfo structs */
+	List	   *aggtransinfos;	/* AggTransInfo structs */
+	int			numOrderedAggs; /* number w/ DISTINCT/ORDER BY/WITHIN GROUP */
+	bool		hasNonPartialAggs;	/* does any agg not support partial mode? */
+	bool		hasNonSerialAggs;	/* is any partial agg non-serializable? */
+
+	/* These fields are used only when hasRecursion is true: */
+	int			wt_param_id;	/* PARAM_EXEC ID for the work table */
+	struct Path *non_recursive_path;	/* a path for non-recursive term */
+
+	/* These fields are workspace for createplan.c */
+	Relids		curOuterRels;	/* outer rels above current node */
+	List	   *curOuterParams; /* not-yet-assigned NestLoopParams */
+
+	/* These fields are workspace for setrefs.c */
+	bool	   *isAltSubplan;	/* array corresponding to glob->subplans */
+	bool	   *isUsedSubplan;	/* array corresponding to glob->subplans */
+
+	/* optional private data for join_search_hook, e.g., GEQO */
+	void	   *join_search_private;
+
+	/* Does this query modify any partition key columns? */
+	bool		partColsUpdated;
+};
+
+
+/*
+ * In places where it's known that simple_rte_array[] must have been prepared
+ * already, we just index into it to fetch RTEs.  In code that might be
+ * executed before or after entering query_planner(), use this macro.
+ */
+#define planner_rt_fetch(rti, root) \
+	((root)->simple_rte_array ? (root)->simple_rte_array[rti] : \
+	 rt_fetch(rti, (root)->parse->rtable))
+
+/*
+ * If multiple relations are partitioned the same way, all such partitions
+ * will have a pointer to the same PartitionScheme.  A list of PartitionScheme
+ * objects is attached to the PlannerInfo.  By design, the partition scheme
+ * incorporates only the general properties of the partition method (LIST vs.
+ * RANGE, number of partitioning columns and the type information for each)
+ * and not the specific bounds.
+ *
+ * We store the opclass-declared input data types instead of the partition key
+ * datatypes since the former rather than the latter are used to compare
+ * partition bounds. Since partition key data types and the opclass declared
+ * input data types are expected to be binary compatible (per ResolveOpClass),
+ * both of those should have same byval and length properties.
+ */
+typedef struct PartitionSchemeData
+{
+	char		strategy;		/* partition strategy */
+	int16		partnatts;		/* number of partition attributes */
+	Oid		   *partopfamily;	/* OIDs of operator families */
+	Oid		   *partopcintype;	/* OIDs of opclass declared input data types */
+	Oid		   *partcollation;	/* OIDs of partitioning collations */
+
+	/* Cached information about partition key data types. */
+	int16	   *parttyplen;
+	bool	   *parttypbyval;
+
+	/* Cached information about partition comparison functions. */
+	struct FmgrInfo *partsupfunc;
+}			PartitionSchemeData;
+
+typedef struct PartitionSchemeData *PartitionScheme;
+
+/*----------
+ * RelOptInfo
+ *		Per-relation information for planning/optimization
+ *
+ * For planning purposes, a "base rel" is either a plain relation (a table)
+ * or the output of a sub-SELECT or function that appears in the range table.
+ * In either case it is uniquely identified by an RT index.  A "joinrel"
+ * is the joining of two or more base rels.  A joinrel is identified by
+ * the set of RT indexes for its component baserels.  We create RelOptInfo
+ * nodes for each baserel and joinrel, and store them in the PlannerInfo's
+ * simple_rel_array and join_rel_list respectively.
+ *
+ * Note that there is only one joinrel for any given set of component
+ * baserels, no matter what order we assemble them in; so an unordered
+ * set is the right datatype to identify it with.
+ *
+ * We also have "other rels", which are like base rels in that they refer to
+ * single RT indexes; but they are not part of the join tree, and are given
+ * a different RelOptKind to identify them.
+ * Currently the only kind of otherrels are those made for member relations
+ * of an "append relation", that is an inheritance set or UNION ALL subquery.
+ * An append relation has a parent RTE that is a base rel, which represents
+ * the entire append relation.  The member RTEs are otherrels.  The parent
+ * is present in the query join tree but the members are not.  The member
+ * RTEs and otherrels are used to plan the scans of the individual tables or
+ * subqueries of the append set; then the parent baserel is given Append
+ * and/or MergeAppend paths comprising the best paths for the individual
+ * member rels.  (See comments for AppendRelInfo for more information.)
+ *
+ * At one time we also made otherrels to represent join RTEs, for use in
+ * handling join alias Vars.  Currently this is not needed because all join
+ * alias Vars are expanded to non-aliased form during preprocess_expression.
+ *
+ * We also have relations representing joins between child relations of
+ * different partitioned tables. These relations are not added to
+ * join_rel_level lists as they are not joined directly by the dynamic
+ * programming algorithm.
+ *
+ * There is also a RelOptKind for "upper" relations, which are RelOptInfos
+ * that describe post-scan/join processing steps, such as aggregation.
+ * Many of the fields in these RelOptInfos are meaningless, but their Path
+ * fields always hold Paths showing ways to do that processing step.
+ *
+ * Lastly, there is a RelOptKind for "dead" relations, which are base rels
+ * that we have proven we don't need to join after all.
+ *
+ * Parts of this data structure are specific to various scan and join
+ * mechanisms.  It didn't seem worth creating new node types for them.
+ *
+ *		relids - Set of base-relation identifiers; it is a base relation
+ *				if there is just one, a join relation if more than one
+ *		rows - estimated number of tuples in the relation after restriction
+ *			   clauses have been applied (ie, output rows of a plan for it)
+ *		consider_startup - true if there is any value in keeping plain paths for
+ *						   this rel on the basis of having cheap startup cost
+ *		consider_param_startup - the same for parameterized paths
+ *		reltarget - Default Path output tlist for this rel; normally contains
+ *					Var and PlaceHolderVar nodes for the values we need to
+ *					output from this relation.
+ *					List is in no particular order, but all rels of an
+ *					appendrel set must use corresponding orders.
+ *					NOTE: in an appendrel child relation, may contain
+ *					arbitrary expressions pulled up from a subquery!
+ *		pathlist - List of Path nodes, one for each potentially useful
+ *				   method of generating the relation
+ *		ppilist - ParamPathInfo nodes for parameterized Paths, if any
+ *		cheapest_startup_path - the pathlist member with lowest startup cost
+ *			(regardless of ordering) among the unparameterized paths;
+ *			or NULL if there is no unparameterized path
+ *		cheapest_total_path - the pathlist member with lowest total cost
+ *			(regardless of ordering) among the unparameterized paths;
+ *			or if there is no unparameterized path, the path with lowest
+ *			total cost among the paths with minimum parameterization
+ *		cheapest_unique_path - for caching cheapest path to produce unique
+ *			(no duplicates) output from relation; NULL if not yet requested
+ *		cheapest_parameterized_paths - best paths for their parameterizations;
+ *			always includes cheapest_total_path, even if that's unparameterized
+ *		direct_lateral_relids - rels this rel has direct LATERAL references to
+ *		lateral_relids - required outer rels for LATERAL, as a Relids set
+ *			(includes both direct and indirect lateral references)
+ *
+ * If the relation is a base relation it will have these fields set:
+ *
+ *		relid - RTE index (this is redundant with the relids field, but
+ *				is provided for convenience of access)
+ *		rtekind - copy of RTE's rtekind field
+ *		min_attr, max_attr - range of valid AttrNumbers for rel
+ *		attr_needed - array of bitmapsets indicating the highest joinrel
+ *				in which each attribute is needed; if bit 0 is set then
+ *				the attribute is needed as part of final targetlist
+ *		attr_widths - cache space for per-attribute width estimates;
+ *					  zero means not computed yet
+ *		lateral_vars - lateral cross-references of rel, if any (list of
+ *					   Vars and PlaceHolderVars)
+ *		lateral_referencers - relids of rels that reference this one laterally
+ *				(includes both direct and indirect lateral references)
+ *		indexlist - list of IndexOptInfo nodes for relation's indexes
+ *					(always NIL if it's not a table)
+ *		pages - number of disk pages in relation (zero if not a table)
+ *		tuples - number of tuples in relation (not considering restrictions)
+ *		allvisfrac - fraction of disk pages that are marked all-visible
+ *		eclass_indexes - EquivalenceClasses that mention this rel (filled
+ *						 only after EC merging is complete)
+ *		subroot - PlannerInfo for subquery (NULL if it's not a subquery)
+ *		subplan_params - list of PlannerParamItems to be passed to subquery
+ *
+ *		Note: for a subquery, tuples and subroot are not set immediately
+ *		upon creation of the RelOptInfo object; they are filled in when
+ *		set_subquery_pathlist processes the object.
+ *
+ *		For otherrels that are appendrel members, these fields are filled
+ *		in just as for a baserel, except we don't bother with lateral_vars.
+ *
+ * If the relation is either a foreign table or a join of foreign tables that
+ * all belong to the same foreign server and are assigned to the same user to
+ * check access permissions as (cf checkAsUser), these fields will be set:
+ *
+ *		serverid - OID of foreign server, if foreign table (else InvalidOid)
+ *		userid - OID of user to check access as (InvalidOid means current user)
+ *		useridiscurrent - we've assumed that userid equals current user
+ *		fdwroutine - function hooks for FDW, if foreign table (else NULL)
+ *		fdw_private - private state for FDW, if foreign table (else NULL)
+ *
+ * Two fields are used to cache knowledge acquired during the join search
+ * about whether this rel is provably unique when being joined to given other
+ * relation(s), ie, it can have at most one row matching any given row from
+ * that join relation.  Currently we only attempt such proofs, and thus only
+ * populate these fields, for base rels; but someday they might be used for
+ * join rels too:
+ *
+ *		unique_for_rels - list of Relid sets, each one being a set of other
+ *					rels for which this one has been proven unique
+ *		non_unique_for_rels - list of Relid sets, each one being a set of
+ *					other rels for which we have tried and failed to prove
+ *					this one unique
+ *
+ * The presence of the following fields depends on the restrictions
+ * and joins that the relation participates in:
+ *
+ *		baserestrictinfo - List of RestrictInfo nodes, containing info about
+ *					each non-join qualification clause in which this relation
+ *					participates (only used for base rels)
+ *		baserestrictcost - Estimated cost of evaluating the baserestrictinfo
+ *					clauses at a single tuple (only used for base rels)
+ *		baserestrict_min_security - Smallest security_level found among
+ *					clauses in baserestrictinfo
+ *		joininfo  - List of RestrictInfo nodes, containing info about each
+ *					join clause in which this relation participates (but
+ *					note this excludes clauses that might be derivable from
+ *					EquivalenceClasses)
+ *		has_eclass_joins - flag that EquivalenceClass joins are possible
+ *
+ * Note: Keeping a restrictinfo list in the RelOptInfo is useful only for
+ * base rels, because for a join rel the set of clauses that are treated as
+ * restrict clauses varies depending on which sub-relations we choose to join.
+ * (For example, in a 3-base-rel join, a clause relating rels 1 and 2 must be
+ * treated as a restrictclause if we join {1} and {2 3} to make {1 2 3}; but
+ * if we join {1 2} and {3} then that clause will be a restrictclause in {1 2}
+ * and should not be processed again at the level of {1 2 3}.)	Therefore,
+ * the restrictinfo list in the join case appears in individual JoinPaths
+ * (field joinrestrictinfo), not in the parent relation.  But it's OK for
+ * the RelOptInfo to store the joininfo list, because that is the same
+ * for a given rel no matter how we form it.
+ *
+ * We store baserestrictcost in the RelOptInfo (for base relations) because
+ * we know we will need it at least once (to price the sequential scan)
+ * and may need it multiple times to price index scans.
+ *
+ * A join relation is considered to be partitioned if it is formed from a
+ * join of two relations that are partitioned, have matching partitioning
+ * schemes, and are joined on an equijoin of the partitioning columns.
+ * Under those conditions we can consider the join relation to be partitioned
+ * by either relation's partitioning keys, though some care is needed if
+ * either relation can be forced to null by outer-joining.  For example, an
+ * outer join like (A LEFT JOIN B ON A.a = B.b) may produce rows with B.b
+ * NULL.  These rows may not fit the partitioning conditions imposed on B.
+ * Hence, strictly speaking, the join is not partitioned by B.b and thus
+ * partition keys of an outer join should include partition key expressions
+ * from the non-nullable side only.  However, if a subsequent join uses
+ * strict comparison operators (and all commonly-used equijoin operators are
+ * strict), the presence of nulls doesn't cause a problem: such rows couldn't
+ * match anything on the other side and thus they don't create a need to do
+ * any cross-partition sub-joins.  Hence we can treat such values as still
+ * partitioning the join output for the purpose of additional partitionwise
+ * joining, so long as a strict join operator is used by the next join.
+ *
+ * If the relation is partitioned, these fields will be set:
+ *
+ *		part_scheme - Partitioning scheme of the relation
+ *		nparts - Number of partitions
+ *		boundinfo - Partition bounds
+ *		partbounds_merged - true if partition bounds are merged ones
+ *		partition_qual - Partition constraint if not the root
+ *		part_rels - RelOptInfos for each partition
+ *		all_partrels - Relids set of all partition relids
+ *		partexprs, nullable_partexprs - Partition key expressions
+ *
+ * The partexprs and nullable_partexprs arrays each contain
+ * part_scheme->partnatts elements.  Each of the elements is a list of
+ * partition key expressions.  For partitioned base relations, there is one
+ * expression in each partexprs element, and nullable_partexprs is empty.
+ * For partitioned join relations, each base relation within the join
+ * contributes one partition key expression per partitioning column;
+ * that expression goes in the partexprs[i] list if the base relation
+ * is not nullable by this join or any lower outer join, or in the
+ * nullable_partexprs[i] list if the base relation is nullable.
+ * Furthermore, FULL JOINs add extra nullable_partexprs expressions
+ * corresponding to COALESCE expressions of the left and right join columns,
+ * to simplify matching join clauses to those lists.
+ *----------
+ */
+
+/* Bitmask of flags supported by table AMs */
+#define AMFLAG_HAS_TID_RANGE (1 << 0)
+
+typedef enum RelOptKind
+{
+	RELOPT_BASEREL,
+	RELOPT_JOINREL,
+	RELOPT_OTHER_MEMBER_REL,
+	RELOPT_OTHER_JOINREL,
+	RELOPT_UPPER_REL,
+	RELOPT_OTHER_UPPER_REL,
+	RELOPT_DEADREL
+} RelOptKind;
+
+/*
+ * Is the given relation a simple relation i.e a base or "other" member
+ * relation?
+ */
+#define IS_SIMPLE_REL(rel) \
+	((rel)->reloptkind == RELOPT_BASEREL || \
+	 (rel)->reloptkind == RELOPT_OTHER_MEMBER_REL)
+
+/* Is the given relation a join relation? */
+#define IS_JOIN_REL(rel)	\
+	((rel)->reloptkind == RELOPT_JOINREL || \
+	 (rel)->reloptkind == RELOPT_OTHER_JOINREL)
+
+/* Is the given relation an upper relation? */
+#define IS_UPPER_REL(rel)	\
+	((rel)->reloptkind == RELOPT_UPPER_REL || \
+	 (rel)->reloptkind == RELOPT_OTHER_UPPER_REL)
+
+/* Is the given relation an "other" relation? */
+#define IS_OTHER_REL(rel) \
+	((rel)->reloptkind == RELOPT_OTHER_MEMBER_REL || \
+	 (rel)->reloptkind == RELOPT_OTHER_JOINREL || \
+	 (rel)->reloptkind == RELOPT_OTHER_UPPER_REL)
+
+typedef struct RelOptInfo
+{
+	NodeTag		type;
+
+	RelOptKind	reloptkind;
+
+	/* all relations included in this RelOptInfo */
+	Relids		relids;			/* set of base relids (rangetable indexes) */
+
+	/* size estimates generated by planner */
+	double		rows;			/* estimated number of result tuples */
+
+	/* per-relation planner control flags */
+	bool		consider_startup;	/* keep cheap-startup-cost paths? */
+	bool		consider_param_startup; /* ditto, for parameterized paths? */
+	bool		consider_parallel;	/* consider parallel paths? */
+
+	/* default result targetlist for Paths scanning this relation */
+	struct PathTarget *reltarget;	/* list of Vars/Exprs, cost, width */
+
+	/* materialization information */
+	List	   *pathlist;		/* Path structures */
+	List	   *ppilist;		/* ParamPathInfos used in pathlist */
+	List	   *partial_pathlist;	/* partial Paths */
+	struct Path *cheapest_startup_path;
+	struct Path *cheapest_total_path;
+	struct Path *cheapest_unique_path;
+	List	   *cheapest_parameterized_paths;
+
+	/* parameterization information needed for both base rels and join rels */
+	/* (see also lateral_vars and lateral_referencers) */
+	Relids		direct_lateral_relids;	/* rels directly laterally referenced */
+	Relids		lateral_relids; /* minimum parameterization of rel */
+
+	/* information about a base rel (not set for join rels!) */
+	Index		relid;
+	Oid			reltablespace;	/* containing tablespace */
+	RTEKind		rtekind;		/* RELATION, SUBQUERY, FUNCTION, etc */
+	AttrNumber	min_attr;		/* smallest attrno of rel (often <0) */
+	AttrNumber	max_attr;		/* largest attrno of rel */
+	Relids	   *attr_needed;	/* array indexed [min_attr .. max_attr] */
+	int32	   *attr_widths;	/* array indexed [min_attr .. max_attr] */
+	List	   *lateral_vars;	/* LATERAL Vars and PHVs referenced by rel */
+	Relids		lateral_referencers;	/* rels that reference me laterally */
+	List	   *indexlist;		/* list of IndexOptInfo */
+	List	   *statlist;		/* list of StatisticExtInfo */
+	BlockNumber pages;			/* size estimates derived from pg_class */
+	double		tuples;
+	double		allvisfrac;
+	Bitmapset  *eclass_indexes; /* Indexes in PlannerInfo's eq_classes list of
+								 * ECs that mention this rel */
+	PlannerInfo *subroot;		/* if subquery */
+	List	   *subplan_params; /* if subquery */
+	int			rel_parallel_workers;	/* wanted number of parallel workers */
+	uint32		amflags;		/* Bitmask of optional features supported by
+								 * the table AM */
+
+	/* Information about foreign tables and foreign joins */
+	Oid			serverid;		/* identifies server for the table or join */
+	Oid			userid;			/* identifies user to check access as */
+	bool		useridiscurrent;	/* join is only valid for current user */
+	/* use "struct FdwRoutine" to avoid including fdwapi.h here */
+	struct FdwRoutine *fdwroutine;
+	void	   *fdw_private;
+
+	/* cache space for remembering if we have proven this relation unique */
+	List	   *unique_for_rels;	/* known unique for these other relid
+									 * set(s) */
+	List	   *non_unique_for_rels;	/* known not unique for these set(s) */
+
+	/* used by various scans and joins: */
+	List	   *baserestrictinfo;	/* RestrictInfo structures (if base rel) */
+	QualCost	baserestrictcost;	/* cost of evaluating the above */
+	Index		baserestrict_min_security;	/* min security_level found in
+											 * baserestrictinfo */
+	List	   *joininfo;		/* RestrictInfo structures for join clauses
+								 * involving this rel */
+	bool		has_eclass_joins;	/* T means joininfo is incomplete */
+
+	/* used by partitionwise joins: */
+	bool		consider_partitionwise_join;	/* consider partitionwise join
+												 * paths? (if partitioned rel) */
+	Relids		top_parent_relids;	/* Relids of topmost parents (if "other"
+									 * rel) */
+
+	/* used for partitioned relations: */
+	PartitionScheme part_scheme;	/* Partitioning scheme */
+	int			nparts;			/* Number of partitions; -1 if not yet set; in
+								 * case of a join relation 0 means it's
+								 * considered unpartitioned */
+	struct PartitionBoundInfoData *boundinfo;	/* Partition bounds */
+	bool		partbounds_merged;	/* True if partition bounds were created
+									 * by partition_bounds_merge() */
+	List	   *partition_qual; /* Partition constraint, if not the root */
+	struct RelOptInfo **part_rels;	/* Array of RelOptInfos of partitions,
+									 * stored in the same order as bounds */
+	Relids		all_partrels;	/* Relids set of all partition relids */
+	List	  **partexprs;		/* Non-nullable partition key expressions */
+	List	  **nullable_partexprs; /* Nullable partition key expressions */
+} RelOptInfo;
+
+/*
+ * Is given relation partitioned?
+ *
+ * It's not enough to test whether rel->part_scheme is set, because it might
+ * be that the basic partitioning properties of the input relations matched
+ * but the partition bounds did not.  Also, if we are able to prove a rel
+ * dummy (empty), we should henceforth treat it as unpartitioned.
+ */
+#define IS_PARTITIONED_REL(rel) \
+	((rel)->part_scheme && (rel)->boundinfo && (rel)->nparts > 0 && \
+	 (rel)->part_rels && !IS_DUMMY_REL(rel))
+
+/*
+ * Convenience macro to make sure that a partitioned relation has all the
+ * required members set.
+ */
+#define REL_HAS_ALL_PART_PROPS(rel)	\
+	((rel)->part_scheme && (rel)->boundinfo && (rel)->nparts > 0 && \
+	 (rel)->part_rels && (rel)->partexprs && (rel)->nullable_partexprs)
+
+/*
+ * IndexOptInfo
+ *		Per-index information for planning/optimization
+ *
+ *		indexkeys[], indexcollations[] each have ncolumns entries.
+ *		opfamily[], and opcintype[]	each have nkeycolumns entries. They do
+ *		not contain any information about included attributes.
+ *
+ *		sortopfamily[], reverse_sort[], and nulls_first[] have
+ *		nkeycolumns entries, if the index is ordered; but if it is unordered,
+ *		those pointers are NULL.
+ *
+ *		Zeroes in the indexkeys[] array indicate index columns that are
+ *		expressions; there is one element in indexprs for each such column.
+ *
+ *		For an ordered index, reverse_sort[] and nulls_first[] describe the
+ *		sort ordering of a forward indexscan; we can also consider a backward
+ *		indexscan, which will generate the reverse ordering.
+ *
+ *		The indexprs and indpred expressions have been run through
+ *		prepqual.c and eval_const_expressions() for ease of matching to
+ *		WHERE clauses. indpred is in implicit-AND form.
+ *
+ *		indextlist is a TargetEntry list representing the index columns.
+ *		It provides an equivalent base-relation Var for each simple column,
+ *		and links to the matching indexprs element for each expression column.
+ *
+ *		While most of these fields are filled when the IndexOptInfo is created
+ *		(by plancat.c), indrestrictinfo and predOK are set later, in
+ *		check_index_predicates().
+ */
+#ifndef HAVE_INDEXOPTINFO_TYPEDEF
+typedef struct IndexOptInfo IndexOptInfo;
+#define HAVE_INDEXOPTINFO_TYPEDEF 1
+#endif
+
+struct IndexOptInfo
+{
+	NodeTag		type;
+
+	Oid			indexoid;		/* OID of the index relation */
+	Oid			reltablespace;	/* tablespace of index (not table) */
+	RelOptInfo *rel;			/* back-link to index's table */
+
+	/* index-size statistics (from pg_class and elsewhere) */
+	BlockNumber pages;			/* number of disk pages in index */
+	double		tuples;			/* number of index tuples in index */
+	int			tree_height;	/* index tree height, or -1 if unknown */
+
+	/* index descriptor information */
+	int			ncolumns;		/* number of columns in index */
+	int			nkeycolumns;	/* number of key columns in index */
+	int		   *indexkeys;		/* column numbers of index's attributes both
+								 * key and included columns, or 0 */
+	Oid		   *indexcollations;	/* OIDs of collations of index columns */
+	Oid		   *opfamily;		/* OIDs of operator families for columns */
+	Oid		   *opcintype;		/* OIDs of opclass declared input data types */
+	Oid		   *sortopfamily;	/* OIDs of btree opfamilies, if orderable */
+	bool	   *reverse_sort;	/* is sort order descending? */
+	bool	   *nulls_first;	/* do NULLs come first in the sort order? */
+	bytea	  **opclassoptions; /* opclass-specific options for columns */
+	bool	   *canreturn;		/* which index cols can be returned in an
+								 * index-only scan? */
+	Oid			relam;			/* OID of the access method (in pg_am) */
+
+	List	   *indexprs;		/* expressions for non-simple index columns */
+	List	   *indpred;		/* predicate if a partial index, else NIL */
+
+	List	   *indextlist;		/* targetlist representing index columns */
+
+	List	   *indrestrictinfo;	/* parent relation's baserestrictinfo
+									 * list, less any conditions implied by
+									 * the index's predicate (unless it's a
+									 * target rel, see comments in
+									 * check_index_predicates()) */
+
+	bool		predOK;			/* true if index predicate matches query */
+	bool		unique;			/* true if a unique index */
+	bool		immediate;		/* is uniqueness enforced immediately? */
+	bool		hypothetical;	/* true if index doesn't really exist */
+
+	/* Remaining fields are copied from the index AM's API struct: */
+	bool		amcanorderbyop; /* does AM support order by operator result? */
+	bool		amoptionalkey;	/* can query omit key for the first column? */
+	bool		amsearcharray;	/* can AM handle ScalarArrayOpExpr quals? */
+	bool		amsearchnulls;	/* can AM search for NULL/NOT NULL entries? */
+	bool		amhasgettuple;	/* does AM have amgettuple interface? */
+	bool		amhasgetbitmap; /* does AM have amgetbitmap interface? */
+	bool		amcanparallel;	/* does AM support parallel scan? */
+	bool		amcanmarkpos;	/* does AM support mark/restore? */
+	/* Rather than include amapi.h here, we declare amcostestimate like this */
+	void		(*amcostestimate) ();	/* AM's cost estimator */
+};
+
+/*
+ * ForeignKeyOptInfo
+ *		Per-foreign-key information for planning/optimization
+ *
+ * The per-FK-column arrays can be fixed-size because we allow at most
+ * INDEX_MAX_KEYS columns in a foreign key constraint.  Each array has
+ * nkeys valid entries.
+ */
+typedef struct ForeignKeyOptInfo
+{
+	NodeTag		type;
+
+	/* Basic data about the foreign key (fetched from catalogs): */
+	Index		con_relid;		/* RT index of the referencing table */
+	Index		ref_relid;		/* RT index of the referenced table */
+	int			nkeys;			/* number of columns in the foreign key */
+	AttrNumber	conkey[INDEX_MAX_KEYS]; /* cols in referencing table */
+	AttrNumber	confkey[INDEX_MAX_KEYS];	/* cols in referenced table */
+	Oid			conpfeqop[INDEX_MAX_KEYS];	/* PK = FK operator OIDs */
+
+	/* Derived info about whether FK's equality conditions match the query: */
+	int			nmatched_ec;	/* # of FK cols matched by ECs */
+	int			nconst_ec;		/* # of these ECs that are ec_has_const */
+	int			nmatched_rcols; /* # of FK cols matched by non-EC rinfos */
+	int			nmatched_ri;	/* total # of non-EC rinfos matched to FK */
+	/* Pointer to eclass matching each column's condition, if there is one */
+	struct EquivalenceClass *eclass[INDEX_MAX_KEYS];
+	/* Pointer to eclass member for the referencing Var, if there is one */
+	struct EquivalenceMember *fk_eclass_member[INDEX_MAX_KEYS];
+	/* List of non-EC RestrictInfos matching each column's condition */
+	List	   *rinfos[INDEX_MAX_KEYS];
+} ForeignKeyOptInfo;
+
+/*
+ * StatisticExtInfo
+ *		Information about extended statistics for planning/optimization
+ *
+ * Each pg_statistic_ext row is represented by one or more nodes of this
+ * type, or even zero if ANALYZE has not computed them.
+ */
+typedef struct StatisticExtInfo
+{
+	NodeTag		type;
+
+	Oid			statOid;		/* OID of the statistics row */
+	RelOptInfo *rel;			/* back-link to statistic's table */
+	char		kind;			/* statistics kind of this entry */
+	Bitmapset  *keys;			/* attnums of the columns covered */
+	List	   *exprs;			/* expressions */
+} StatisticExtInfo;
+
+/*
+ * EquivalenceClasses
+ *
+ * Whenever we can determine that a mergejoinable equality clause A = B is
+ * not delayed by any outer join, we create an EquivalenceClass containing
+ * the expressions A and B to record this knowledge.  If we later find another
+ * equivalence B = C, we add C to the existing EquivalenceClass; this may
+ * require merging two existing EquivalenceClasses.  At the end of the qual
+ * distribution process, we have sets of values that are known all transitively
+ * equal to each other, where "equal" is according to the rules of the btree
+ * operator family(s) shown in ec_opfamilies, as well as the collation shown
+ * by ec_collation.  (We restrict an EC to contain only equalities whose
+ * operators belong to the same set of opfamilies.  This could probably be
+ * relaxed, but for now it's not worth the trouble, since nearly all equality
+ * operators belong to only one btree opclass anyway.  Similarly, we suppose
+ * that all or none of the input datatypes are collatable, so that a single
+ * collation value is sufficient.)
+ *
+ * We also use EquivalenceClasses as the base structure for PathKeys, letting
+ * us represent knowledge about different sort orderings being equivalent.
+ * Since every PathKey must reference an EquivalenceClass, we will end up
+ * with single-member EquivalenceClasses whenever a sort key expression has
+ * not been equivalenced to anything else.  It is also possible that such an
+ * EquivalenceClass will contain a volatile expression ("ORDER BY random()"),
+ * which is a case that can't arise otherwise since clauses containing
+ * volatile functions are never considered mergejoinable.  We mark such
+ * EquivalenceClasses specially to prevent them from being merged with
+ * ordinary EquivalenceClasses.  Also, for volatile expressions we have
+ * to be careful to match the EquivalenceClass to the correct targetlist
+ * entry: consider SELECT random() AS a, random() AS b ... ORDER BY b,a.
+ * So we record the SortGroupRef of the originating sort clause.
+ *
+ * We allow equality clauses appearing below the nullable side of an outer join
+ * to form EquivalenceClasses, but these have a slightly different meaning:
+ * the included values might be all NULL rather than all the same non-null
+ * values.  See src/backend/optimizer/README for more on that point.
+ *
+ * NB: if ec_merged isn't NULL, this class has been merged into another, and
+ * should be ignored in favor of using the pointed-to class.
+ */
+typedef struct EquivalenceClass
+{
+	NodeTag		type;
+
+	List	   *ec_opfamilies;	/* btree operator family OIDs */
+	Oid			ec_collation;	/* collation, if datatypes are collatable */
+	List	   *ec_members;		/* list of EquivalenceMembers */
+	List	   *ec_sources;		/* list of generating RestrictInfos */
+	List	   *ec_derives;		/* list of derived RestrictInfos */
+	Relids		ec_relids;		/* all relids appearing in ec_members, except
+								 * for child members (see below) */
+	bool		ec_has_const;	/* any pseudoconstants in ec_members? */
+	bool		ec_has_volatile;	/* the (sole) member is a volatile expr */
+	bool		ec_below_outer_join;	/* equivalence applies below an OJ */
+	bool		ec_broken;		/* failed to generate needed clauses? */
+	Index		ec_sortref;		/* originating sortclause label, or 0 */
+	Index		ec_min_security;	/* minimum security_level in ec_sources */
+	Index		ec_max_security;	/* maximum security_level in ec_sources */
+	struct EquivalenceClass *ec_merged; /* set if merged into another EC */
+} EquivalenceClass;
+
+/*
+ * If an EC contains a const and isn't below-outer-join, any PathKey depending
+ * on it must be redundant, since there's only one possible value of the key.
+ */
+#define EC_MUST_BE_REDUNDANT(eclass)  \
+	((eclass)->ec_has_const && !(eclass)->ec_below_outer_join)
+
+/*
+ * EquivalenceMember - one member expression of an EquivalenceClass
+ *
+ * em_is_child signifies that this element was built by transposing a member
+ * for an appendrel parent relation to represent the corresponding expression
+ * for an appendrel child.  These members are used for determining the
+ * pathkeys of scans on the child relation and for explicitly sorting the
+ * child when necessary to build a MergeAppend path for the whole appendrel
+ * tree.  An em_is_child member has no impact on the properties of the EC as a
+ * whole; in particular the EC's ec_relids field does NOT include the child
+ * relation.  An em_is_child member should never be marked em_is_const nor
+ * cause ec_has_const or ec_has_volatile to be set, either.  Thus, em_is_child
+ * members are not really full-fledged members of the EC, but just reflections
+ * or doppelgangers of real members.  Most operations on EquivalenceClasses
+ * should ignore em_is_child members, and those that don't should test
+ * em_relids to make sure they only consider relevant members.
+ *
+ * em_datatype is usually the same as exprType(em_expr), but can be
+ * different when dealing with a binary-compatible opfamily; in particular
+ * anyarray_ops would never work without this.  Use em_datatype when
+ * looking up a specific btree operator to work with this expression.
+ */
+typedef struct EquivalenceMember
+{
+	NodeTag		type;
+
+	Expr	   *em_expr;		/* the expression represented */
+	Relids		em_relids;		/* all relids appearing in em_expr */
+	Relids		em_nullable_relids; /* nullable by lower outer joins */
+	bool		em_is_const;	/* expression is pseudoconstant? */
+	bool		em_is_child;	/* derived version for a child relation? */
+	Oid			em_datatype;	/* the "nominal type" used by the opfamily */
+} EquivalenceMember;
+
+/*
+ * PathKeys
+ *
+ * The sort ordering of a path is represented by a list of PathKey nodes.
+ * An empty list implies no known ordering.  Otherwise the first item
+ * represents the primary sort key, the second the first secondary sort key,
+ * etc.  The value being sorted is represented by linking to an
+ * EquivalenceClass containing that value and including pk_opfamily among its
+ * ec_opfamilies.  The EquivalenceClass tells which collation to use, too.
+ * This is a convenient method because it makes it trivial to detect
+ * equivalent and closely-related orderings. (See optimizer/README for more
+ * information.)
+ *
+ * Note: pk_strategy is either BTLessStrategyNumber (for ASC) or
+ * BTGreaterStrategyNumber (for DESC).  We assume that all ordering-capable
+ * index types will use btree-compatible strategy numbers.
+ */
+typedef struct PathKey
+{
+	NodeTag		type;
+
+	EquivalenceClass *pk_eclass;	/* the value that is ordered */
+	Oid			pk_opfamily;	/* btree opfamily defining the ordering */
+	int			pk_strategy;	/* sort direction (ASC or DESC) */
+	bool		pk_nulls_first; /* do NULLs come before normal values? */
+} PathKey;
+
+/*
+ * VolatileFunctionStatus -- allows nodes to cache their
+ * contain_volatile_functions properties. VOLATILITY_UNKNOWN means not yet
+ * determined.
+ */
+typedef enum VolatileFunctionStatus
+{
+	VOLATILITY_UNKNOWN = 0,
+	VOLATILITY_VOLATILE,
+	VOLATILITY_NOVOLATILE
+} VolatileFunctionStatus;
+
+/*
+ * PathTarget
+ *
+ * This struct contains what we need to know during planning about the
+ * targetlist (output columns) that a Path will compute.  Each RelOptInfo
+ * includes a default PathTarget, which its individual Paths may simply
+ * reference.  However, in some cases a Path may compute outputs different
+ * from other Paths, and in that case we make a custom PathTarget for it.
+ * For example, an indexscan might return index expressions that would
+ * otherwise need to be explicitly calculated.  (Note also that "upper"
+ * relations generally don't have useful default PathTargets.)
+ *
+ * exprs contains bare expressions; they do not have TargetEntry nodes on top,
+ * though those will appear in finished Plans.
+ *
+ * sortgrouprefs[] is an array of the same length as exprs, containing the
+ * corresponding sort/group refnos, or zeroes for expressions not referenced
+ * by sort/group clauses.  If sortgrouprefs is NULL (which it generally is in
+ * RelOptInfo.reltarget targets; only upper-level Paths contain this info),
+ * we have not identified sort/group columns in this tlist.  This allows us to
+ * deal with sort/group refnos when needed with less expense than including
+ * TargetEntry nodes in the exprs list.
+ */
+typedef struct PathTarget
+{
+	NodeTag		type;
+	List	   *exprs;			/* list of expressions to be computed */
+	Index	   *sortgrouprefs;	/* corresponding sort/group refnos, or 0 */
+	QualCost	cost;			/* cost of evaluating the expressions */
+	int			width;			/* estimated avg width of result tuples */
+	VolatileFunctionStatus has_volatile_expr;	/* indicates if exprs contain
+												 * any volatile functions. */
+} PathTarget;
+
+/* Convenience macro to get a sort/group refno from a PathTarget */
+#define get_pathtarget_sortgroupref(target, colno) \
+	((target)->sortgrouprefs ? (target)->sortgrouprefs[colno] : (Index) 0)
+
+
+/*
+ * ParamPathInfo
+ *
+ * All parameterized paths for a given relation with given required outer rels
+ * link to a single ParamPathInfo, which stores common information such as
+ * the estimated rowcount for this parameterization.  We do this partly to
+ * avoid recalculations, but mostly to ensure that the estimated rowcount
+ * is in fact the same for every such path.
+ *
+ * Note: ppi_clauses is only used in ParamPathInfos for base relation paths;
+ * in join cases it's NIL because the set of relevant clauses varies depending
+ * on how the join is formed.  The relevant clauses will appear in each
+ * parameterized join path's joinrestrictinfo list, instead.
+ */
+typedef struct ParamPathInfo
+{
+	NodeTag		type;
+
+	Relids		ppi_req_outer;	/* rels supplying parameters used by path */
+	double		ppi_rows;		/* estimated number of result tuples */
+	List	   *ppi_clauses;	/* join clauses available from outer rels */
+} ParamPathInfo;
+
+
+/*
+ * Type "Path" is used as-is for sequential-scan paths, as well as some other
+ * simple plan types that we don't need any extra information in the path for.
+ * For other path types it is the first component of a larger struct.
+ *
+ * "pathtype" is the NodeTag of the Plan node we could build from this Path.
+ * It is partially redundant with the Path's NodeTag, but allows us to use
+ * the same Path type for multiple Plan types when there is no need to
+ * distinguish the Plan type during path processing.
+ *
+ * "parent" identifies the relation this Path scans, and "pathtarget"
+ * describes the precise set of output columns the Path would compute.
+ * In simple cases all Paths for a given rel share the same targetlist,
+ * which we represent by having path->pathtarget equal to parent->reltarget.
+ *
+ * "param_info", if not NULL, links to a ParamPathInfo that identifies outer
+ * relation(s) that provide parameter values to each scan of this path.
+ * That means this path can only be joined to those rels by means of nestloop
+ * joins with this path on the inside.  Also note that a parameterized path
+ * is responsible for testing all "movable" joinclauses involving this rel
+ * and the specified outer rel(s).
+ *
+ * "rows" is the same as parent->rows in simple paths, but in parameterized
+ * paths and UniquePaths it can be less than parent->rows, reflecting the
+ * fact that we've filtered by extra join conditions or removed duplicates.
+ *
+ * "pathkeys" is a List of PathKey nodes (see above), describing the sort
+ * ordering of the path's output rows.
+ */
+typedef struct Path
+{
+	NodeTag		type;
+
+	NodeTag		pathtype;		/* tag identifying scan/join method */
+
+	RelOptInfo *parent;			/* the relation this path can build */
+	PathTarget *pathtarget;		/* list of Vars/Exprs, cost, width */
+
+	ParamPathInfo *param_info;	/* parameterization info, or NULL if none */
+
+	bool		parallel_aware; /* engage parallel-aware logic? */
+	bool		parallel_safe;	/* OK to use as part of parallel plan? */
+	int			parallel_workers;	/* desired # of workers; 0 = not parallel */
+
+	/* estimated size/costs for path (see costsize.c for more info) */
+	double		rows;			/* estimated number of result tuples */
+	Cost		startup_cost;	/* cost expended before fetching any tuples */
+	Cost		total_cost;		/* total cost (assuming all tuples fetched) */
+
+	List	   *pathkeys;		/* sort ordering of path's output */
+	/* pathkeys is a List of PathKey nodes; see above */
+} Path;
+
+/* Macro for extracting a path's parameterization relids; beware double eval */
+#define PATH_REQ_OUTER(path)  \
+	((path)->param_info ? (path)->param_info->ppi_req_outer : (Relids) NULL)
+
+/*----------
+ * IndexPath represents an index scan over a single index.
+ *
+ * This struct is used for both regular indexscans and index-only scans;
+ * path.pathtype is T_IndexScan or T_IndexOnlyScan to show which is meant.
+ *
+ * 'indexinfo' is the index to be scanned.
+ *
+ * 'indexclauses' is a list of IndexClause nodes, each representing one
+ * index-checkable restriction, with implicit AND semantics across the list.
+ * An empty list implies a full index scan.
+ *
+ * 'indexorderbys', if not NIL, is a list of ORDER BY expressions that have
+ * been found to be usable as ordering operators for an amcanorderbyop index.
+ * The list must match the path's pathkeys, ie, one expression per pathkey
+ * in the same order.  These are not RestrictInfos, just bare expressions,
+ * since they generally won't yield booleans.  It's guaranteed that each
+ * expression has the index key on the left side of the operator.
+ *
+ * 'indexorderbycols' is an integer list of index column numbers (zero-based)
+ * of the same length as 'indexorderbys', showing which index column each
+ * ORDER BY expression is meant to be used with.  (There is no restriction
+ * on which index column each ORDER BY can be used with.)
+ *
+ * 'indexscandir' is one of:
+ *		ForwardScanDirection: forward scan of an ordered index
+ *		BackwardScanDirection: backward scan of an ordered index
+ *		NoMovementScanDirection: scan of an unordered index, or don't care
+ * (The executor doesn't care whether it gets ForwardScanDirection or
+ * NoMovementScanDirection for an indexscan, but the planner wants to
+ * distinguish ordered from unordered indexes for building pathkeys.)
+ *
+ * 'indextotalcost' and 'indexselectivity' are saved in the IndexPath so that
+ * we need not recompute them when considering using the same index in a
+ * bitmap index/heap scan (see BitmapHeapPath).  The costs of the IndexPath
+ * itself represent the costs of an IndexScan or IndexOnlyScan plan type.
+ *----------
+ */
+typedef struct IndexPath
+{
+	Path		path;
+	IndexOptInfo *indexinfo;
+	List	   *indexclauses;
+	List	   *indexorderbys;
+	List	   *indexorderbycols;
+	ScanDirection indexscandir;
+	Cost		indextotalcost;
+	Selectivity indexselectivity;
+} IndexPath;
+
+/*
+ * Each IndexClause references a RestrictInfo node from the query's WHERE
+ * or JOIN conditions, and shows how that restriction can be applied to
+ * the particular index.  We support both indexclauses that are directly
+ * usable by the index machinery, which are typically of the form
+ * "indexcol OP pseudoconstant", and those from which an indexable qual
+ * can be derived.  The simplest such transformation is that a clause
+ * of the form "pseudoconstant OP indexcol" can be commuted to produce an
+ * indexable qual (the index machinery expects the indexcol to be on the
+ * left always).  Another example is that we might be able to extract an
+ * indexable range condition from a LIKE condition, as in "x LIKE 'foo%bar'"
+ * giving rise to "x >= 'foo' AND x < 'fop'".  Derivation of such lossy
+ * conditions is done by a planner support function attached to the
+ * indexclause's top-level function or operator.
+ *
+ * indexquals is a list of RestrictInfos for the directly-usable index
+ * conditions associated with this IndexClause.  In the simplest case
+ * it's a one-element list whose member is iclause->rinfo.  Otherwise,
+ * it contains one or more directly-usable indexqual conditions extracted
+ * from the given clause.  The 'lossy' flag indicates whether the
+ * indexquals are semantically equivalent to the original clause, or
+ * represent a weaker condition.
+ *
+ * Normally, indexcol is the index of the single index column the clause
+ * works on, and indexcols is NIL.  But if the clause is a RowCompareExpr,
+ * indexcol is the index of the leading column, and indexcols is a list of
+ * all the affected columns.  (Note that indexcols matches up with the
+ * columns of the actual indexable RowCompareExpr in indexquals, which
+ * might be different from the original in rinfo.)
+ *
+ * An IndexPath's IndexClause list is required to be ordered by index
+ * column, i.e. the indexcol values must form a nondecreasing sequence.
+ * (The order of multiple clauses for the same index column is unspecified.)
+ */
+typedef struct IndexClause
+{
+	NodeTag		type;
+	struct RestrictInfo *rinfo; /* original restriction or join clause */
+	List	   *indexquals;		/* indexqual(s) derived from it */
+	bool		lossy;			/* are indexquals a lossy version of clause? */
+	AttrNumber	indexcol;		/* index column the clause uses (zero-based) */
+	List	   *indexcols;		/* multiple index columns, if RowCompare */
+} IndexClause;
+
+/*
+ * BitmapHeapPath represents one or more indexscans that generate TID bitmaps
+ * instead of directly accessing the heap, followed by AND/OR combinations
+ * to produce a single bitmap, followed by a heap scan that uses the bitmap.
+ * Note that the output is always considered unordered, since it will come
+ * out in physical heap order no matter what the underlying indexes did.
+ *
+ * The individual indexscans are represented by IndexPath nodes, and any
+ * logic on top of them is represented by a tree of BitmapAndPath and
+ * BitmapOrPath nodes.  Notice that we can use the same IndexPath node both
+ * to represent a regular (or index-only) index scan plan, and as the child
+ * of a BitmapHeapPath that represents scanning the same index using a
+ * BitmapIndexScan.  The startup_cost and total_cost figures of an IndexPath
+ * always represent the costs to use it as a regular (or index-only)
+ * IndexScan.  The costs of a BitmapIndexScan can be computed using the
+ * IndexPath's indextotalcost and indexselectivity.
+ */
+typedef struct BitmapHeapPath
+{
+	Path		path;
+	Path	   *bitmapqual;		/* IndexPath, BitmapAndPath, BitmapOrPath */
+} BitmapHeapPath;
+
+/*
+ * BitmapAndPath represents a BitmapAnd plan node; it can only appear as
+ * part of the substructure of a BitmapHeapPath.  The Path structure is
+ * a bit more heavyweight than we really need for this, but for simplicity
+ * we make it a derivative of Path anyway.
+ */
+typedef struct BitmapAndPath
+{
+	Path		path;
+	List	   *bitmapquals;	/* IndexPaths and BitmapOrPaths */
+	Selectivity bitmapselectivity;
+} BitmapAndPath;
+
+/*
+ * BitmapOrPath represents a BitmapOr plan node; it can only appear as
+ * part of the substructure of a BitmapHeapPath.  The Path structure is
+ * a bit more heavyweight than we really need for this, but for simplicity
+ * we make it a derivative of Path anyway.
+ */
+typedef struct BitmapOrPath
+{
+	Path		path;
+	List	   *bitmapquals;	/* IndexPaths and BitmapAndPaths */
+	Selectivity bitmapselectivity;
+} BitmapOrPath;
+
+/*
+ * TidPath represents a scan by TID
+ *
+ * tidquals is an implicitly OR'ed list of qual expressions of the form
+ * "CTID = pseudoconstant", or "CTID = ANY(pseudoconstant_array)",
+ * or a CurrentOfExpr for the relation.
+ */
+typedef struct TidPath
+{
+	Path		path;
+	List	   *tidquals;		/* qual(s) involving CTID = something */
+} TidPath;
+
+/*
+ * TidRangePath represents a scan by a continguous range of TIDs
+ *
+ * tidrangequals is an implicitly AND'ed list of qual expressions of the form
+ * "CTID relop pseudoconstant", where relop is one of >,>=,<,<=.
+ */
+typedef struct TidRangePath
+{
+	Path		path;
+	List	   *tidrangequals;
+} TidRangePath;
+
+/*
+ * SubqueryScanPath represents a scan of an unflattened subquery-in-FROM
+ *
+ * Note that the subpath comes from a different planning domain; for example
+ * RTE indexes within it mean something different from those known to the
+ * SubqueryScanPath.  path.parent->subroot is the planning context needed to
+ * interpret the subpath.
+ */
+typedef struct SubqueryScanPath
+{
+	Path		path;
+	Path	   *subpath;		/* path representing subquery execution */
+} SubqueryScanPath;
+
+/*
+ * ForeignPath represents a potential scan of a foreign table, foreign join
+ * or foreign upper-relation.
+ *
+ * fdw_private stores FDW private data about the scan.  While fdw_private is
+ * not actually touched by the core code during normal operations, it's
+ * generally a good idea to use a representation that can be dumped by
+ * nodeToString(), so that you can examine the structure during debugging
+ * with tools like pprint().
+ */
+typedef struct ForeignPath
+{
+	Path		path;
+	Path	   *fdw_outerpath;
+	List	   *fdw_private;
+} ForeignPath;
+
+/*
+ * CustomPath represents a table scan done by some out-of-core extension.
+ *
+ * We provide a set of hooks here - which the provider must take care to set
+ * up correctly - to allow extensions to supply their own methods of scanning
+ * a relation.  For example, a provider might provide GPU acceleration, a
+ * cache-based scan, or some other kind of logic we haven't dreamed up yet.
+ *
+ * CustomPaths can be injected into the planning process for a relation by
+ * set_rel_pathlist_hook functions.
+ *
+ * Core code must avoid assuming that the CustomPath is only as large as
+ * the structure declared here; providers are allowed to make it the first
+ * element in a larger structure.  (Since the planner never copies Paths,
+ * this doesn't add any complication.)  However, for consistency with the
+ * FDW case, we provide a "custom_private" field in CustomPath; providers
+ * may prefer to use that rather than define another struct type.
+ */
+
+struct CustomPathMethods;
+
+typedef struct CustomPath
+{
+	Path		path;
+	uint32		flags;			/* mask of CUSTOMPATH_* flags, see
+								 * nodes/extensible.h */
+	List	   *custom_paths;	/* list of child Path nodes, if any */
+	List	   *custom_private;
+	const struct CustomPathMethods *methods;
+} CustomPath;
+
+/*
+ * AppendPath represents an Append plan, ie, successive execution of
+ * several member plans.
+ *
+ * For partial Append, 'subpaths' contains non-partial subpaths followed by
+ * partial subpaths.
+ *
+ * Note: it is possible for "subpaths" to contain only one, or even no,
+ * elements.  These cases are optimized during create_append_plan.
+ * In particular, an AppendPath with no subpaths is a "dummy" path that
+ * is created to represent the case that a relation is provably empty.
+ * (This is a convenient representation because it means that when we build
+ * an appendrel and find that all its children have been excluded, no extra
+ * action is needed to recognize the relation as dummy.)
+ */
+typedef struct AppendPath
+{
+	Path		path;
+	List	   *subpaths;		/* list of component Paths */
+	/* Index of first partial path in subpaths; list_length(subpaths) if none */
+	int			first_partial_path;
+	double		limit_tuples;	/* hard limit on output tuples, or -1 */
+} AppendPath;
+
+#define IS_DUMMY_APPEND(p) \
+	(IsA((p), AppendPath) && ((AppendPath *) (p))->subpaths == NIL)
+
+/*
+ * A relation that's been proven empty will have one path that is dummy
+ * (but might have projection paths on top).  For historical reasons,
+ * this is provided as a macro that wraps is_dummy_rel().
+ */
+#define IS_DUMMY_REL(r) is_dummy_rel(r)
+extern bool is_dummy_rel(RelOptInfo *rel);
+
+/*
+ * MergeAppendPath represents a MergeAppend plan, ie, the merging of sorted
+ * results from several member plans to produce similarly-sorted output.
+ */
+typedef struct MergeAppendPath
+{
+	Path		path;
+	List	   *subpaths;		/* list of component Paths */
+	double		limit_tuples;	/* hard limit on output tuples, or -1 */
+} MergeAppendPath;
+
+/*
+ * GroupResultPath represents use of a Result plan node to compute the
+ * output of a degenerate GROUP BY case, wherein we know we should produce
+ * exactly one row, which might then be filtered by a HAVING qual.
+ *
+ * Note that quals is a list of bare clauses, not RestrictInfos.
+ */
+typedef struct GroupResultPath
+{
+	Path		path;
+	List	   *quals;
+} GroupResultPath;
+
+/*
+ * MaterialPath represents use of a Material plan node, i.e., caching of
+ * the output of its subpath.  This is used when the subpath is expensive
+ * and needs to be scanned repeatedly, or when we need mark/restore ability
+ * and the subpath doesn't have it.
+ */
+typedef struct MaterialPath
+{
+	Path		path;
+	Path	   *subpath;
+} MaterialPath;
+
+/*
+ * MemoizePath represents a Memoize plan node, i.e., a cache that caches
+ * tuples from parameterized paths to save the underlying node from having to
+ * be rescanned for parameter values which are already cached.
+ */
+typedef struct MemoizePath
+{
+	Path		path;
+	Path	   *subpath;		/* outerpath to cache tuples from */
+	List	   *hash_operators; /* hash operators for each key */
+	List	   *param_exprs;	/* cache keys */
+	bool		singlerow;		/* true if the cache entry is to be marked as
+								 * complete after caching the first record. */
+	bool		binary_mode;	/* true when cache key should be compared bit
+								 * by bit, false when using hash equality ops */
+	double		calls;			/* expected number of rescans */
+	uint32		est_entries;	/* The maximum number of entries that the
+								 * planner expects will fit in the cache, or 0
+								 * if unknown */
+} MemoizePath;
+
+/*
+ * UniquePath represents elimination of distinct rows from the output of
+ * its subpath.
+ *
+ * This can represent significantly different plans: either hash-based or
+ * sort-based implementation, or a no-op if the input path can be proven
+ * distinct already.  The decision is sufficiently localized that it's not
+ * worth having separate Path node types.  (Note: in the no-op case, we could
+ * eliminate the UniquePath node entirely and just return the subpath; but
+ * it's convenient to have a UniquePath in the path tree to signal upper-level
+ * routines that the input is known distinct.)
+ */
+typedef enum
+{
+	UNIQUE_PATH_NOOP,			/* input is known unique already */
+	UNIQUE_PATH_HASH,			/* use hashing */
+	UNIQUE_PATH_SORT			/* use sorting */
+} UniquePathMethod;
+
+typedef struct UniquePath
+{
+	Path		path;
+	Path	   *subpath;
+	UniquePathMethod umethod;
+	List	   *in_operators;	/* equality operators of the IN clause */
+	List	   *uniq_exprs;		/* expressions to be made unique */
+} UniquePath;
+
+/*
+ * GatherPath runs several copies of a plan in parallel and collects the
+ * results.  The parallel leader may also execute the plan, unless the
+ * single_copy flag is set.
+ */
+typedef struct GatherPath
+{
+	Path		path;
+	Path	   *subpath;		/* path for each worker */
+	bool		single_copy;	/* don't execute path more than once */
+	int			num_workers;	/* number of workers sought to help */
+} GatherPath;
+
+/*
+ * GatherMergePath runs several copies of a plan in parallel and collects
+ * the results, preserving their common sort order.
+ */
+typedef struct GatherMergePath
+{
+	Path		path;
+	Path	   *subpath;		/* path for each worker */
+	int			num_workers;	/* number of workers sought to help */
+} GatherMergePath;
+
+
+/*
+ * All join-type paths share these fields.
+ */
+
+typedef struct JoinPath
+{
+	Path		path;
+
+	JoinType	jointype;
+
+	bool		inner_unique;	/* each outer tuple provably matches no more
+								 * than one inner tuple */
+
+	Path	   *outerjoinpath;	/* path for the outer side of the join */
+	Path	   *innerjoinpath;	/* path for the inner side of the join */
+
+	List	   *joinrestrictinfo;	/* RestrictInfos to apply to join */
+
+	/*
+	 * See the notes for RelOptInfo and ParamPathInfo to understand why
+	 * joinrestrictinfo is needed in JoinPath, and can't be merged into the
+	 * parent RelOptInfo.
+	 */
+} JoinPath;
+
+/*
+ * A nested-loop path needs no special fields.
+ */
+
+typedef JoinPath NestPath;
+
+/*
+ * A mergejoin path has these fields.
+ *
+ * Unlike other path types, a MergePath node doesn't represent just a single
+ * run-time plan node: it can represent up to four.  Aside from the MergeJoin
+ * node itself, there can be a Sort node for the outer input, a Sort node
+ * for the inner input, and/or a Material node for the inner input.  We could
+ * represent these nodes by separate path nodes, but considering how many
+ * different merge paths are investigated during a complex join problem,
+ * it seems better to avoid unnecessary palloc overhead.
+ *
+ * path_mergeclauses lists the clauses (in the form of RestrictInfos)
+ * that will be used in the merge.
+ *
+ * Note that the mergeclauses are a subset of the parent relation's
+ * restriction-clause list.  Any join clauses that are not mergejoinable
+ * appear only in the parent's restrict list, and must be checked by a
+ * qpqual at execution time.
+ *
+ * outersortkeys (resp. innersortkeys) is NIL if the outer path
+ * (resp. inner path) is already ordered appropriately for the
+ * mergejoin.  If it is not NIL then it is a PathKeys list describing
+ * the ordering that must be created by an explicit Sort node.
+ *
+ * skip_mark_restore is true if the executor need not do mark/restore calls.
+ * Mark/restore overhead is usually required, but can be skipped if we know
+ * that the executor need find only one match per outer tuple, and that the
+ * mergeclauses are sufficient to identify a match.  In such cases the
+ * executor can immediately advance the outer relation after processing a
+ * match, and therefore it need never back up the inner relation.
+ *
+ * materialize_inner is true if a Material node should be placed atop the
+ * inner input.  This may appear with or without an inner Sort step.
+ */
+
+typedef struct MergePath
+{
+	JoinPath	jpath;
+	List	   *path_mergeclauses;	/* join clauses to be used for merge */
+	List	   *outersortkeys;	/* keys for explicit sort, if any */
+	List	   *innersortkeys;	/* keys for explicit sort, if any */
+	bool		skip_mark_restore;	/* can executor skip mark/restore? */
+	bool		materialize_inner;	/* add Materialize to inner? */
+} MergePath;
+
+/*
+ * A hashjoin path has these fields.
+ *
+ * The remarks above for mergeclauses apply for hashclauses as well.
+ *
+ * Hashjoin does not care what order its inputs appear in, so we have
+ * no need for sortkeys.
+ */
+
+typedef struct HashPath
+{
+	JoinPath	jpath;
+	List	   *path_hashclauses;	/* join clauses used for hashing */
+	int			num_batches;	/* number of batches expected */
+	double		inner_rows_total;	/* total inner rows expected */
+} HashPath;
+
+/*
+ * ProjectionPath represents a projection (that is, targetlist computation)
+ *
+ * Nominally, this path node represents using a Result plan node to do a
+ * projection step.  However, if the input plan node supports projection,
+ * we can just modify its output targetlist to do the required calculations
+ * directly, and not need a Result.  In some places in the planner we can just
+ * jam the desired PathTarget into the input path node (and adjust its cost
+ * accordingly), so we don't need a ProjectionPath.  But in other places
+ * it's necessary to not modify the input path node, so we need a separate
+ * ProjectionPath node, which is marked dummy to indicate that we intend to
+ * assign the work to the input plan node.  The estimated cost for the
+ * ProjectionPath node will account for whether a Result will be used or not.
+ */
+typedef struct ProjectionPath
+{
+	Path		path;
+	Path	   *subpath;		/* path representing input source */
+	bool		dummypp;		/* true if no separate Result is needed */
+} ProjectionPath;
+
+/*
+ * ProjectSetPath represents evaluation of a targetlist that includes
+ * set-returning function(s), which will need to be implemented by a
+ * ProjectSet plan node.
+ */
+typedef struct ProjectSetPath
+{
+	Path		path;
+	Path	   *subpath;		/* path representing input source */
+} ProjectSetPath;
+
+/*
+ * SortPath represents an explicit sort step
+ *
+ * The sort keys are, by definition, the same as path.pathkeys.
+ *
+ * Note: the Sort plan node cannot project, so path.pathtarget must be the
+ * same as the input's pathtarget.
+ */
+typedef struct SortPath
+{
+	Path		path;
+	Path	   *subpath;		/* path representing input source */
+} SortPath;
+
+/*
+ * IncrementalSortPath represents an incremental sort step
+ *
+ * This is like a regular sort, except some leading key columns are assumed
+ * to be ordered already.
+ */
+typedef struct IncrementalSortPath
+{
+	SortPath	spath;
+	int			nPresortedCols; /* number of presorted columns */
+} IncrementalSortPath;
+
+/*
+ * GroupPath represents grouping (of presorted input)
+ *
+ * groupClause represents the columns to be grouped on; the input path
+ * must be at least that well sorted.
+ *
+ * We can also apply a qual to the grouped rows (equivalent of HAVING)
+ */
+typedef struct GroupPath
+{
+	Path		path;
+	Path	   *subpath;		/* path representing input source */
+	List	   *groupClause;	/* a list of SortGroupClause's */
+	List	   *qual;			/* quals (HAVING quals), if any */
+} GroupPath;
+
+/*
+ * UpperUniquePath represents adjacent-duplicate removal (in presorted input)
+ *
+ * The columns to be compared are the first numkeys columns of the path's
+ * pathkeys.  The input is presumed already sorted that way.
+ */
+typedef struct UpperUniquePath
+{
+	Path		path;
+	Path	   *subpath;		/* path representing input source */
+	int			numkeys;		/* number of pathkey columns to compare */
+} UpperUniquePath;
+
+/*
+ * AggPath represents generic computation of aggregate functions
+ *
+ * This may involve plain grouping (but not grouping sets), using either
+ * sorted or hashed grouping; for the AGG_SORTED case, the input must be
+ * appropriately presorted.
+ */
+typedef struct AggPath
+{
+	Path		path;
+	Path	   *subpath;		/* path representing input source */
+	AggStrategy aggstrategy;	/* basic strategy, see nodes.h */
+	AggSplit	aggsplit;		/* agg-splitting mode, see nodes.h */
+	double		numGroups;		/* estimated number of groups in input */
+	uint64		transitionSpace;	/* for pass-by-ref transition data */
+	List	   *groupClause;	/* a list of SortGroupClause's */
+	List	   *qual;			/* quals (HAVING quals), if any */
+} AggPath;
+
+/*
+ * Various annotations used for grouping sets in the planner.
+ */
+
+typedef struct GroupingSetData
+{
+	NodeTag		type;
+	List	   *set;			/* grouping set as list of sortgrouprefs */
+	double		numGroups;		/* est. number of result groups */
+} GroupingSetData;
+
+typedef struct RollupData
+{
+	NodeTag		type;
+	List	   *groupClause;	/* applicable subset of parse->groupClause */
+	List	   *gsets;			/* lists of integer indexes into groupClause */
+	List	   *gsets_data;		/* list of GroupingSetData */
+	double		numGroups;		/* est. number of result groups */
+	bool		hashable;		/* can be hashed */
+	bool		is_hashed;		/* to be implemented as a hashagg */
+} RollupData;
+
+/*
+ * GroupingSetsPath represents a GROUPING SETS aggregation
+ */
+
+typedef struct GroupingSetsPath
+{
+	Path		path;
+	Path	   *subpath;		/* path representing input source */
+	AggStrategy aggstrategy;	/* basic strategy */
+	List	   *rollups;		/* list of RollupData */
+	List	   *qual;			/* quals (HAVING quals), if any */
+	uint64		transitionSpace;	/* for pass-by-ref transition data */
+} GroupingSetsPath;
+
+/*
+ * MinMaxAggPath represents computation of MIN/MAX aggregates from indexes
+ */
+typedef struct MinMaxAggPath
+{
+	Path		path;
+	List	   *mmaggregates;	/* list of MinMaxAggInfo */
+	List	   *quals;			/* HAVING quals, if any */
+} MinMaxAggPath;
+
+/*
+ * WindowAggPath represents generic computation of window functions
+ */
+typedef struct WindowAggPath
+{
+	Path		path;
+	Path	   *subpath;		/* path representing input source */
+	WindowClause *winclause;	/* WindowClause we'll be using */
+} WindowAggPath;
+
+/*
+ * SetOpPath represents a set-operation, that is INTERSECT or EXCEPT
+ */
+typedef struct SetOpPath
+{
+	Path		path;
+	Path	   *subpath;		/* path representing input source */
+	SetOpCmd	cmd;			/* what to do, see nodes.h */
+	SetOpStrategy strategy;		/* how to do it, see nodes.h */
+	List	   *distinctList;	/* SortGroupClauses identifying target cols */
+	AttrNumber	flagColIdx;		/* where is the flag column, if any */
+	int			firstFlag;		/* flag value for first input relation */
+	double		numGroups;		/* estimated number of groups in input */
+} SetOpPath;
+
+/*
+ * RecursiveUnionPath represents a recursive UNION node
+ */
+typedef struct RecursiveUnionPath
+{
+	Path		path;
+	Path	   *leftpath;		/* paths representing input sources */
+	Path	   *rightpath;
+	List	   *distinctList;	/* SortGroupClauses identifying target cols */
+	int			wtParam;		/* ID of Param representing work table */
+	double		numGroups;		/* estimated number of groups in input */
+} RecursiveUnionPath;
+
+/*
+ * LockRowsPath represents acquiring row locks for SELECT FOR UPDATE/SHARE
+ */
+typedef struct LockRowsPath
+{
+	Path		path;
+	Path	   *subpath;		/* path representing input source */
+	List	   *rowMarks;		/* a list of PlanRowMark's */
+	int			epqParam;		/* ID of Param for EvalPlanQual re-eval */
+} LockRowsPath;
+
+/*
+ * ModifyTablePath represents performing INSERT/UPDATE/DELETE modifications
+ *
+ * We represent most things that will be in the ModifyTable plan node
+ * literally, except we have a child Path not Plan.  But analysis of the
+ * OnConflictExpr is deferred to createplan.c, as is collection of FDW data.
+ */
+typedef struct ModifyTablePath
+{
+	Path		path;
+	Path	   *subpath;		/* Path producing source data */
+	CmdType		operation;		/* INSERT, UPDATE, or DELETE */
+	bool		canSetTag;		/* do we set the command tag/es_processed? */
+	Index		nominalRelation;	/* Parent RT index for use of EXPLAIN */
+	Index		rootRelation;	/* Root RT index, if target is partitioned */
+	bool		partColsUpdated;	/* some part key in hierarchy updated? */
+	List	   *resultRelations;	/* integer list of RT indexes */
+	List	   *updateColnosLists;	/* per-target-table update_colnos lists */
+	List	   *withCheckOptionLists;	/* per-target-table WCO lists */
+	List	   *returningLists; /* per-target-table RETURNING tlists */
+	List	   *rowMarks;		/* PlanRowMarks (non-locking only) */
+	OnConflictExpr *onconflict; /* ON CONFLICT clause, or NULL */
+	int			epqParam;		/* ID of Param for EvalPlanQual re-eval */
+} ModifyTablePath;
+
+/*
+ * LimitPath represents applying LIMIT/OFFSET restrictions
+ */
+typedef struct LimitPath
+{
+	Path		path;
+	Path	   *subpath;		/* path representing input source */
+	Node	   *limitOffset;	/* OFFSET parameter, or NULL if none */
+	Node	   *limitCount;		/* COUNT parameter, or NULL if none */
+	LimitOption limitOption;	/* FETCH FIRST with ties or exact number */
+} LimitPath;
+
+
+/*
+ * Restriction clause info.
+ *
+ * We create one of these for each AND sub-clause of a restriction condition
+ * (WHERE or JOIN/ON clause).  Since the restriction clauses are logically
+ * ANDed, we can use any one of them or any subset of them to filter out
+ * tuples, without having to evaluate the rest.  The RestrictInfo node itself
+ * stores data used by the optimizer while choosing the best query plan.
+ *
+ * If a restriction clause references a single base relation, it will appear
+ * in the baserestrictinfo list of the RelOptInfo for that base rel.
+ *
+ * If a restriction clause references more than one base rel, it will
+ * appear in the joininfo list of every RelOptInfo that describes a strict
+ * subset of the base rels mentioned in the clause.  The joininfo lists are
+ * used to drive join tree building by selecting plausible join candidates.
+ * The clause cannot actually be applied until we have built a join rel
+ * containing all the base rels it references, however.
+ *
+ * When we construct a join rel that includes all the base rels referenced
+ * in a multi-relation restriction clause, we place that clause into the
+ * joinrestrictinfo lists of paths for the join rel, if neither left nor
+ * right sub-path includes all base rels referenced in the clause.  The clause
+ * will be applied at that join level, and will not propagate any further up
+ * the join tree.  (Note: the "predicate migration" code was once intended to
+ * push restriction clauses up and down the plan tree based on evaluation
+ * costs, but it's dead code and is unlikely to be resurrected in the
+ * foreseeable future.)
+ *
+ * Note that in the presence of more than two rels, a multi-rel restriction
+ * might reach different heights in the join tree depending on the join
+ * sequence we use.  So, these clauses cannot be associated directly with
+ * the join RelOptInfo, but must be kept track of on a per-join-path basis.
+ *
+ * RestrictInfos that represent equivalence conditions (i.e., mergejoinable
+ * equalities that are not outerjoin-delayed) are handled a bit differently.
+ * Initially we attach them to the EquivalenceClasses that are derived from
+ * them.  When we construct a scan or join path, we look through all the
+ * EquivalenceClasses and generate derived RestrictInfos representing the
+ * minimal set of conditions that need to be checked for this particular scan
+ * or join to enforce that all members of each EquivalenceClass are in fact
+ * equal in all rows emitted by the scan or join.
+ *
+ * When dealing with outer joins we have to be very careful about pushing qual
+ * clauses up and down the tree.  An outer join's own JOIN/ON conditions must
+ * be evaluated exactly at that join node, unless they are "degenerate"
+ * conditions that reference only Vars from the nullable side of the join.
+ * Quals appearing in WHERE or in a JOIN above the outer join cannot be pushed
+ * down below the outer join, if they reference any nullable Vars.
+ * RestrictInfo nodes contain a flag to indicate whether a qual has been
+ * pushed down to a lower level than its original syntactic placement in the
+ * join tree would suggest.  If an outer join prevents us from pushing a qual
+ * down to its "natural" semantic level (the level associated with just the
+ * base rels used in the qual) then we mark the qual with a "required_relids"
+ * value including more than just the base rels it actually uses.  By
+ * pretending that the qual references all the rels required to form the outer
+ * join, we prevent it from being evaluated below the outer join's joinrel.
+ * When we do form the outer join's joinrel, we still need to distinguish
+ * those quals that are actually in that join's JOIN/ON condition from those
+ * that appeared elsewhere in the tree and were pushed down to the join rel
+ * because they used no other rels.  That's what the is_pushed_down flag is
+ * for; it tells us that a qual is not an OUTER JOIN qual for the set of base
+ * rels listed in required_relids.  A clause that originally came from WHERE
+ * or an INNER JOIN condition will *always* have its is_pushed_down flag set.
+ * It's possible for an OUTER JOIN clause to be marked is_pushed_down too,
+ * if we decide that it can be pushed down into the nullable side of the join.
+ * In that case it acts as a plain filter qual for wherever it gets evaluated.
+ * (In short, is_pushed_down is only false for non-degenerate outer join
+ * conditions.  Possibly we should rename it to reflect that meaning?  But
+ * see also the comments for RINFO_IS_PUSHED_DOWN, below.)
+ *
+ * RestrictInfo nodes also contain an outerjoin_delayed flag, which is true
+ * if the clause's applicability must be delayed due to any outer joins
+ * appearing below it (ie, it has to be postponed to some join level higher
+ * than the set of relations it actually references).
+ *
+ * There is also an outer_relids field, which is NULL except for outer join
+ * clauses; for those, it is the set of relids on the outer side of the
+ * clause's outer join.  (These are rels that the clause cannot be applied to
+ * in parameterized scans, since pushing it into the join's outer side would
+ * lead to wrong answers.)
+ *
+ * There is also a nullable_relids field, which is the set of rels the clause
+ * references that can be forced null by some outer join below the clause.
+ *
+ * outerjoin_delayed = true is subtly different from nullable_relids != NULL:
+ * a clause might reference some nullable rels and yet not be
+ * outerjoin_delayed because it also references all the other rels of the
+ * outer join(s). A clause that is not outerjoin_delayed can be enforced
+ * anywhere it is computable.
+ *
+ * To handle security-barrier conditions efficiently, we mark RestrictInfo
+ * nodes with a security_level field, in which higher values identify clauses
+ * coming from less-trusted sources.  The exact semantics are that a clause
+ * cannot be evaluated before another clause with a lower security_level value
+ * unless the first clause is leakproof.  As with outer-join clauses, this
+ * creates a reason for clauses to sometimes need to be evaluated higher in
+ * the join tree than their contents would suggest; and even at a single plan
+ * node, this rule constrains the order of application of clauses.
+ *
+ * In general, the referenced clause might be arbitrarily complex.  The
+ * kinds of clauses we can handle as indexscan quals, mergejoin clauses,
+ * or hashjoin clauses are limited (e.g., no volatile functions).  The code
+ * for each kind of path is responsible for identifying the restrict clauses
+ * it can use and ignoring the rest.  Clauses not implemented by an indexscan,
+ * mergejoin, or hashjoin will be placed in the plan qual or joinqual field
+ * of the finished Plan node, where they will be enforced by general-purpose
+ * qual-expression-evaluation code.  (But we are still entitled to count
+ * their selectivity when estimating the result tuple count, if we
+ * can guess what it is...)
+ *
+ * When the referenced clause is an OR clause, we generate a modified copy
+ * in which additional RestrictInfo nodes are inserted below the top-level
+ * OR/AND structure.  This is a convenience for OR indexscan processing:
+ * indexquals taken from either the top level or an OR subclause will have
+ * associated RestrictInfo nodes.
+ *
+ * The can_join flag is set true if the clause looks potentially useful as
+ * a merge or hash join clause, that is if it is a binary opclause with
+ * nonoverlapping sets of relids referenced in the left and right sides.
+ * (Whether the operator is actually merge or hash joinable isn't checked,
+ * however.)
+ *
+ * The pseudoconstant flag is set true if the clause contains no Vars of
+ * the current query level and no volatile functions.  Such a clause can be
+ * pulled out and used as a one-time qual in a gating Result node.  We keep
+ * pseudoconstant clauses in the same lists as other RestrictInfos so that
+ * the regular clause-pushing machinery can assign them to the correct join
+ * level, but they need to be treated specially for cost and selectivity
+ * estimates.  Note that a pseudoconstant clause can never be an indexqual
+ * or merge or hash join clause, so it's of no interest to large parts of
+ * the planner.
+ *
+ * When join clauses are generated from EquivalenceClasses, there may be
+ * several equally valid ways to enforce join equivalence, of which we need
+ * apply only one.  We mark clauses of this kind by setting parent_ec to
+ * point to the generating EquivalenceClass.  Multiple clauses with the same
+ * parent_ec in the same join are redundant.
+ */
+
+typedef struct RestrictInfo
+{
+	NodeTag		type;
+
+	Expr	   *clause;			/* the represented clause of WHERE or JOIN */
+
+	bool		is_pushed_down; /* true if clause was pushed down in level */
+
+	bool		outerjoin_delayed;	/* true if delayed by lower outer join */
+
+	bool		can_join;		/* see comment above */
+
+	bool		pseudoconstant; /* see comment above */
+
+	bool		leakproof;		/* true if known to contain no leaked Vars */
+
+	VolatileFunctionStatus has_volatile;	/* to indicate if clause contains
+											 * any volatile functions. */
+
+	Index		security_level; /* see comment above */
+
+	/* The set of relids (varnos) actually referenced in the clause: */
+	Relids		clause_relids;
+
+	/* The set of relids required to evaluate the clause: */
+	Relids		required_relids;
+
+	/* If an outer-join clause, the outer-side relations, else NULL: */
+	Relids		outer_relids;
+
+	/* The relids used in the clause that are nullable by lower outer joins: */
+	Relids		nullable_relids;
+
+	/* These fields are set for any binary opclause: */
+	Relids		left_relids;	/* relids in left side of clause */
+	Relids		right_relids;	/* relids in right side of clause */
+
+	/* This field is NULL unless clause is an OR clause: */
+	Expr	   *orclause;		/* modified clause with RestrictInfos */
+
+	/* This field is NULL unless clause is potentially redundant: */
+	EquivalenceClass *parent_ec;	/* generating EquivalenceClass */
+
+	/* cache space for cost and selectivity */
+	QualCost	eval_cost;		/* eval cost of clause; -1 if not yet set */
+	Selectivity norm_selec;		/* selectivity for "normal" (JOIN_INNER)
+								 * semantics; -1 if not yet set; >1 means a
+								 * redundant clause */
+	Selectivity outer_selec;	/* selectivity for outer join semantics; -1 if
+								 * not yet set */
+
+	/* valid if clause is mergejoinable, else NIL */
+	List	   *mergeopfamilies;	/* opfamilies containing clause operator */
+
+	/* cache space for mergeclause processing; NULL if not yet set */
+	EquivalenceClass *left_ec;	/* EquivalenceClass containing lefthand */
+	EquivalenceClass *right_ec; /* EquivalenceClass containing righthand */
+	EquivalenceMember *left_em; /* EquivalenceMember for lefthand */
+	EquivalenceMember *right_em;	/* EquivalenceMember for righthand */
+	List	   *scansel_cache;	/* list of MergeScanSelCache structs */
+
+	/* transient workspace for use while considering a specific join path */
+	bool		outer_is_left;	/* T = outer var on left, F = on right */
+
+	/* valid if clause is hashjoinable, else InvalidOid: */
+	Oid			hashjoinoperator;	/* copy of clause operator */
+
+	/* cache space for hashclause processing; -1 if not yet set */
+	Selectivity left_bucketsize;	/* avg bucketsize of left side */
+	Selectivity right_bucketsize;	/* avg bucketsize of right side */
+	Selectivity left_mcvfreq;	/* left side's most common val's freq */
+	Selectivity right_mcvfreq;	/* right side's most common val's freq */
+
+	/* hash equality operator used for memoize nodes, else InvalidOid */
+	Oid			hasheqoperator;
+} RestrictInfo;
+
+/*
+ * This macro embodies the correct way to test whether a RestrictInfo is
+ * "pushed down" to a given outer join, that is, should be treated as a filter
+ * clause rather than a join clause at that outer join.  This is certainly so
+ * if is_pushed_down is true; but examining that is not sufficient anymore,
+ * because outer-join clauses will get pushed down to lower outer joins when
+ * we generate a path for the lower outer join that is parameterized by the
+ * LHS of the upper one.  We can detect such a clause by noting that its
+ * required_relids exceed the scope of the join.
+ */
+#define RINFO_IS_PUSHED_DOWN(rinfo, joinrelids) \
+	((rinfo)->is_pushed_down || \
+	 !bms_is_subset((rinfo)->required_relids, joinrelids))
+
+/*
+ * Since mergejoinscansel() is a relatively expensive function, and would
+ * otherwise be invoked many times while planning a large join tree,
+ * we go out of our way to cache its results.  Each mergejoinable
+ * RestrictInfo carries a list of the specific sort orderings that have
+ * been considered for use with it, and the resulting selectivities.
+ */
+typedef struct MergeScanSelCache
+{
+	/* Ordering details (cache lookup key) */
+	Oid			opfamily;		/* btree opfamily defining the ordering */
+	Oid			collation;		/* collation for the ordering */
+	int			strategy;		/* sort direction (ASC or DESC) */
+	bool		nulls_first;	/* do NULLs come before normal values? */
+	/* Results */
+	Selectivity leftstartsel;	/* first-join fraction for clause left side */
+	Selectivity leftendsel;		/* last-join fraction for clause left side */
+	Selectivity rightstartsel;	/* first-join fraction for clause right side */
+	Selectivity rightendsel;	/* last-join fraction for clause right side */
+} MergeScanSelCache;
+
+/*
+ * Placeholder node for an expression to be evaluated below the top level
+ * of a plan tree.  This is used during planning to represent the contained
+ * expression.  At the end of the planning process it is replaced by either
+ * the contained expression or a Var referring to a lower-level evaluation of
+ * the contained expression.  Typically the evaluation occurs below an outer
+ * join, and Var references above the outer join might thereby yield NULL
+ * instead of the expression value.
+ *
+ * Although the planner treats this as an expression node type, it is not
+ * recognized by the parser or executor, so we declare it here rather than
+ * in primnodes.h.
+ */
+
+typedef struct PlaceHolderVar
+{
+	Expr		xpr;
+	Expr	   *phexpr;			/* the represented expression */
+	Relids		phrels;			/* base relids syntactically within expr src */
+	Index		phid;			/* ID for PHV (unique within planner run) */
+	Index		phlevelsup;		/* > 0 if PHV belongs to outer query */
+} PlaceHolderVar;
+
+/*
+ * "Special join" info.
+ *
+ * One-sided outer joins constrain the order of joining partially but not
+ * completely.  We flatten such joins into the planner's top-level list of
+ * relations to join, but record information about each outer join in a
+ * SpecialJoinInfo struct.  These structs are kept in the PlannerInfo node's
+ * join_info_list.
+ *
+ * Similarly, semijoins and antijoins created by flattening IN (subselect)
+ * and EXISTS(subselect) clauses create partial constraints on join order.
+ * These are likewise recorded in SpecialJoinInfo structs.
+ *
+ * We make SpecialJoinInfos for FULL JOINs even though there is no flexibility
+ * of planning for them, because this simplifies make_join_rel()'s API.
+ *
+ * min_lefthand and min_righthand are the sets of base relids that must be
+ * available on each side when performing the special join.  lhs_strict is
+ * true if the special join's condition cannot succeed when the LHS variables
+ * are all NULL (this means that an outer join can commute with upper-level
+ * outer joins even if it appears in their RHS).  We don't bother to set
+ * lhs_strict for FULL JOINs, however.
+ *
+ * It is not valid for either min_lefthand or min_righthand to be empty sets;
+ * if they were, this would break the logic that enforces join order.
+ *
+ * syn_lefthand and syn_righthand are the sets of base relids that are
+ * syntactically below this special join.  (These are needed to help compute
+ * min_lefthand and min_righthand for higher joins.)
+ *
+ * delay_upper_joins is set true if we detect a pushed-down clause that has
+ * to be evaluated after this join is formed (because it references the RHS).
+ * Any outer joins that have such a clause and this join in their RHS cannot
+ * commute with this join, because that would leave noplace to check the
+ * pushed-down clause.  (We don't track this for FULL JOINs, either.)
+ *
+ * For a semijoin, we also extract the join operators and their RHS arguments
+ * and set semi_operators, semi_rhs_exprs, semi_can_btree, and semi_can_hash.
+ * This is done in support of possibly unique-ifying the RHS, so we don't
+ * bother unless at least one of semi_can_btree and semi_can_hash can be set
+ * true.  (You might expect that this information would be computed during
+ * join planning; but it's helpful to have it available during planning of
+ * parameterized table scans, so we store it in the SpecialJoinInfo structs.)
+ *
+ * jointype is never JOIN_RIGHT; a RIGHT JOIN is handled by switching
+ * the inputs to make it a LEFT JOIN.  So the allowed values of jointype
+ * in a join_info_list member are only LEFT, FULL, SEMI, or ANTI.
+ *
+ * For purposes of join selectivity estimation, we create transient
+ * SpecialJoinInfo structures for regular inner joins; so it is possible
+ * to have jointype == JOIN_INNER in such a structure, even though this is
+ * not allowed within join_info_list.  We also create transient
+ * SpecialJoinInfos with jointype == JOIN_INNER for outer joins, since for
+ * cost estimation purposes it is sometimes useful to know the join size under
+ * plain innerjoin semantics.  Note that lhs_strict, delay_upper_joins, and
+ * of course the semi_xxx fields are not set meaningfully within such structs.
+ */
+#ifndef HAVE_SPECIALJOININFO_TYPEDEF
+typedef struct SpecialJoinInfo SpecialJoinInfo;
+#define HAVE_SPECIALJOININFO_TYPEDEF 1
+#endif
+
+struct SpecialJoinInfo
+{
+	NodeTag		type;
+	Relids		min_lefthand;	/* base relids in minimum LHS for join */
+	Relids		min_righthand;	/* base relids in minimum RHS for join */
+	Relids		syn_lefthand;	/* base relids syntactically within LHS */
+	Relids		syn_righthand;	/* base relids syntactically within RHS */
+	JoinType	jointype;		/* always INNER, LEFT, FULL, SEMI, or ANTI */
+	bool		lhs_strict;		/* joinclause is strict for some LHS rel */
+	bool		delay_upper_joins;	/* can't commute with upper RHS */
+	/* Remaining fields are set only for JOIN_SEMI jointype: */
+	bool		semi_can_btree; /* true if semi_operators are all btree */
+	bool		semi_can_hash;	/* true if semi_operators are all hash */
+	List	   *semi_operators; /* OIDs of equality join operators */
+	List	   *semi_rhs_exprs; /* righthand-side expressions of these ops */
+};
+
+/*
+ * Append-relation info.
+ *
+ * When we expand an inheritable table or a UNION-ALL subselect into an
+ * "append relation" (essentially, a list of child RTEs), we build an
+ * AppendRelInfo for each child RTE.  The list of AppendRelInfos indicates
+ * which child RTEs must be included when expanding the parent, and each node
+ * carries information needed to translate between columns of the parent and
+ * columns of the child.
+ *
+ * These structs are kept in the PlannerInfo node's append_rel_list, with
+ * append_rel_array[] providing a convenient lookup method for the struct
+ * associated with a particular child relid (there can be only one, though
+ * parent rels may have many entries in append_rel_list).
+ *
+ * Note: after completion of the planner prep phase, any given RTE is an
+ * append parent having entries in append_rel_list if and only if its
+ * "inh" flag is set.  We clear "inh" for plain tables that turn out not
+ * to have inheritance children, and (in an abuse of the original meaning
+ * of the flag) we set "inh" for subquery RTEs that turn out to be
+ * flattenable UNION ALL queries.  This lets us avoid useless searches
+ * of append_rel_list.
+ *
+ * Note: the data structure assumes that append-rel members are single
+ * baserels.  This is OK for inheritance, but it prevents us from pulling
+ * up a UNION ALL member subquery if it contains a join.  While that could
+ * be fixed with a more complex data structure, at present there's not much
+ * point because no improvement in the plan could result.
+ */
+
+typedef struct AppendRelInfo
+{
+	NodeTag		type;
+
+	/*
+	 * These fields uniquely identify this append relationship.  There can be
+	 * (in fact, always should be) multiple AppendRelInfos for the same
+	 * parent_relid, but never more than one per child_relid, since a given
+	 * RTE cannot be a child of more than one append parent.
+	 */
+	Index		parent_relid;	/* RT index of append parent rel */
+	Index		child_relid;	/* RT index of append child rel */
+
+	/*
+	 * For an inheritance appendrel, the parent and child are both regular
+	 * relations, and we store their rowtype OIDs here for use in translating
+	 * whole-row Vars.  For a UNION-ALL appendrel, the parent and child are
+	 * both subqueries with no named rowtype, and we store InvalidOid here.
+	 */
+	Oid			parent_reltype; /* OID of parent's composite type */
+	Oid			child_reltype;	/* OID of child's composite type */
+
+	/*
+	 * The N'th element of this list is a Var or expression representing the
+	 * child column corresponding to the N'th column of the parent. This is
+	 * used to translate Vars referencing the parent rel into references to
+	 * the child.  A list element is NULL if it corresponds to a dropped
+	 * column of the parent (this is only possible for inheritance cases, not
+	 * UNION ALL).  The list elements are always simple Vars for inheritance
+	 * cases, but can be arbitrary expressions in UNION ALL cases.
+	 *
+	 * Notice we only store entries for user columns (attno > 0).  Whole-row
+	 * Vars are special-cased, and system columns (attno < 0) need no special
+	 * translation since their attnos are the same for all tables.
+	 *
+	 * Caution: the Vars have varlevelsup = 0.  Be careful to adjust as needed
+	 * when copying into a subquery.
+	 */
+	List	   *translated_vars;	/* Expressions in the child's Vars */
+
+	/*
+	 * This array simplifies translations in the reverse direction, from
+	 * child's column numbers to parent's.  The entry at [ccolno - 1] is the
+	 * 1-based parent column number for child column ccolno, or zero if that
+	 * child column is dropped or doesn't exist in the parent.
+	 */
+	int			num_child_cols; /* length of array */
+	AttrNumber *parent_colnos;	/* array of parent attnos, or zeroes */
+
+	/*
+	 * We store the parent table's OID here for inheritance, or InvalidOid for
+	 * UNION ALL.  This is only needed to help in generating error messages if
+	 * an attempt is made to reference a dropped parent column.
+	 */
+	Oid			parent_reloid;	/* OID of parent relation */
+} AppendRelInfo;
+
+/*
+ * Information about a row-identity "resjunk" column in UPDATE/DELETE.
+ *
+ * In partitioned UPDATE/DELETE it's important for child partitions to share
+ * row-identity columns whenever possible, so as not to chew up too many
+ * targetlist columns.  We use these structs to track which identity columns
+ * have been requested.  In the finished plan, each of these will give rise
+ * to one resjunk entry in the targetlist of the ModifyTable's subplan node.
+ *
+ * All the Vars stored in RowIdentityVarInfos must have varno ROWID_VAR, for
+ * convenience of detecting duplicate requests.  We'll replace that, in the
+ * final plan, with the varno of the generating rel.
+ *
+ * Outside this list, a Var with varno ROWID_VAR and varattno k is a reference
+ * to the k-th element of the row_identity_vars list (k counting from 1).
+ * We add such a reference to root->processed_tlist when creating the entry,
+ * and it propagates into the plan tree from there.
+ */
+typedef struct RowIdentityVarInfo
+{
+	NodeTag		type;
+
+	Var		   *rowidvar;		/* Var to be evaluated (but varno=ROWID_VAR) */
+	int32		rowidwidth;		/* estimated average width */
+	char	   *rowidname;		/* name of the resjunk column */
+	Relids		rowidrels;		/* RTE indexes of target rels using this */
+} RowIdentityVarInfo;
+
+/*
+ * For each distinct placeholder expression generated during planning, we
+ * store a PlaceHolderInfo node in the PlannerInfo node's placeholder_list.
+ * This stores info that is needed centrally rather than in each copy of the
+ * PlaceHolderVar.  The phid fields identify which PlaceHolderInfo goes with
+ * each PlaceHolderVar.  Note that phid is unique throughout a planner run,
+ * not just within a query level --- this is so that we need not reassign ID's
+ * when pulling a subquery into its parent.
+ *
+ * The idea is to evaluate the expression at (only) the ph_eval_at join level,
+ * then allow it to bubble up like a Var until the ph_needed join level.
+ * ph_needed has the same definition as attr_needed for a regular Var.
+ *
+ * The PlaceHolderVar's expression might contain LATERAL references to vars
+ * coming from outside its syntactic scope.  If so, those rels are *not*
+ * included in ph_eval_at, but they are recorded in ph_lateral.
+ *
+ * Notice that when ph_eval_at is a join rather than a single baserel, the
+ * PlaceHolderInfo may create constraints on join order: the ph_eval_at join
+ * has to be formed below any outer joins that should null the PlaceHolderVar.
+ *
+ * We create a PlaceHolderInfo only after determining that the PlaceHolderVar
+ * is actually referenced in the plan tree, so that unreferenced placeholders
+ * don't result in unnecessary constraints on join order.
+ */
+
+typedef struct PlaceHolderInfo
+{
+	NodeTag		type;
+
+	Index		phid;			/* ID for PH (unique within planner run) */
+	PlaceHolderVar *ph_var;		/* copy of PlaceHolderVar tree */
+	Relids		ph_eval_at;		/* lowest level we can evaluate value at */
+	Relids		ph_lateral;		/* relids of contained lateral refs, if any */
+	Relids		ph_needed;		/* highest level the value is needed at */
+	int32		ph_width;		/* estimated attribute width */
+} PlaceHolderInfo;
+
+/*
+ * This struct describes one potentially index-optimizable MIN/MAX aggregate
+ * function.  MinMaxAggPath contains a list of these, and if we accept that
+ * path, the list is stored into root->minmax_aggs for use during setrefs.c.
+ */
+typedef struct MinMaxAggInfo
+{
+	NodeTag		type;
+
+	Oid			aggfnoid;		/* pg_proc Oid of the aggregate */
+	Oid			aggsortop;		/* Oid of its sort operator */
+	Expr	   *target;			/* expression we are aggregating on */
+	PlannerInfo *subroot;		/* modified "root" for planning the subquery */
+	Path	   *path;			/* access path for subquery */
+	Cost		pathcost;		/* estimated cost to fetch first row */
+	Param	   *param;			/* param for subplan's output */
+} MinMaxAggInfo;
+
+/*
+ * At runtime, PARAM_EXEC slots are used to pass values around from one plan
+ * node to another.  They can be used to pass values down into subqueries (for
+ * outer references in subqueries), or up out of subqueries (for the results
+ * of a subplan), or from a NestLoop plan node into its inner relation (when
+ * the inner scan is parameterized with values from the outer relation).
+ * The planner is responsible for assigning nonconflicting PARAM_EXEC IDs to
+ * the PARAM_EXEC Params it generates.
+ *
+ * Outer references are managed via root->plan_params, which is a list of
+ * PlannerParamItems.  While planning a subquery, each parent query level's
+ * plan_params contains the values required from it by the current subquery.
+ * During create_plan(), we use plan_params to track values that must be
+ * passed from outer to inner sides of NestLoop plan nodes.
+ *
+ * The item a PlannerParamItem represents can be one of three kinds:
+ *
+ * A Var: the slot represents a variable of this level that must be passed
+ * down because subqueries have outer references to it, or must be passed
+ * from a NestLoop node to its inner scan.  The varlevelsup value in the Var
+ * will always be zero.
+ *
+ * A PlaceHolderVar: this works much like the Var case, except that the
+ * entry is a PlaceHolderVar node with a contained expression.  The PHV
+ * will have phlevelsup = 0, and the contained expression is adjusted
+ * to match in level.
+ *
+ * An Aggref (with an expression tree representing its argument): the slot
+ * represents an aggregate expression that is an outer reference for some
+ * subquery.  The Aggref itself has agglevelsup = 0, and its argument tree
+ * is adjusted to match in level.
+ *
+ * Note: we detect duplicate Var and PlaceHolderVar parameters and coalesce
+ * them into one slot, but we do not bother to do that for Aggrefs.
+ * The scope of duplicate-elimination only extends across the set of
+ * parameters passed from one query level into a single subquery, or for
+ * nestloop parameters across the set of nestloop parameters used in a single
+ * query level.  So there is no possibility of a PARAM_EXEC slot being used
+ * for conflicting purposes.
+ *
+ * In addition, PARAM_EXEC slots are assigned for Params representing outputs
+ * from subplans (values that are setParam items for those subplans).  These
+ * IDs need not be tracked via PlannerParamItems, since we do not need any
+ * duplicate-elimination nor later processing of the represented expressions.
+ * Instead, we just record the assignment of the slot number by appending to
+ * root->glob->paramExecTypes.
+ */
+typedef struct PlannerParamItem
+{
+	NodeTag		type;
+
+	Node	   *item;			/* the Var, PlaceHolderVar, or Aggref */
+	int			paramId;		/* its assigned PARAM_EXEC slot number */
+} PlannerParamItem;
+
+/*
+ * When making cost estimates for a SEMI/ANTI/inner_unique join, there are
+ * some correction factors that are needed in both nestloop and hash joins
+ * to account for the fact that the executor can stop scanning inner rows
+ * as soon as it finds a match to the current outer row.  These numbers
+ * depend only on the selected outer and inner join relations, not on the
+ * particular paths used for them, so it's worthwhile to calculate them
+ * just once per relation pair not once per considered path.  This struct
+ * is filled by compute_semi_anti_join_factors and must be passed along
+ * to the join cost estimation functions.
+ *
+ * outer_match_frac is the fraction of the outer tuples that are
+ *		expected to have at least one match.
+ * match_count is the average number of matches expected for
+ *		outer tuples that have at least one match.
+ */
+typedef struct SemiAntiJoinFactors
+{
+	Selectivity outer_match_frac;
+	Selectivity match_count;
+} SemiAntiJoinFactors;
+
+/*
+ * Struct for extra information passed to subroutines of add_paths_to_joinrel
+ *
+ * restrictlist contains all of the RestrictInfo nodes for restriction
+ *		clauses that apply to this join
+ * mergeclause_list is a list of RestrictInfo nodes for available
+ *		mergejoin clauses in this join
+ * inner_unique is true if each outer tuple provably matches no more
+ *		than one inner tuple
+ * sjinfo is extra info about special joins for selectivity estimation
+ * semifactors is as shown above (only valid for SEMI/ANTI/inner_unique joins)
+ * param_source_rels are OK targets for parameterization of result paths
+ */
+typedef struct JoinPathExtraData
+{
+	List	   *restrictlist;
+	List	   *mergeclause_list;
+	bool		inner_unique;
+	SpecialJoinInfo *sjinfo;
+	SemiAntiJoinFactors semifactors;
+	Relids		param_source_rels;
+} JoinPathExtraData;
+
+/*
+ * Various flags indicating what kinds of grouping are possible.
+ *
+ * GROUPING_CAN_USE_SORT should be set if it's possible to perform
+ * sort-based implementations of grouping.  When grouping sets are in use,
+ * this will be true if sorting is potentially usable for any of the grouping
+ * sets, even if it's not usable for all of them.
+ *
+ * GROUPING_CAN_USE_HASH should be set if it's possible to perform
+ * hash-based implementations of grouping.
+ *
+ * GROUPING_CAN_PARTIAL_AGG should be set if the aggregation is of a type
+ * for which we support partial aggregation (not, for example, grouping sets).
+ * It says nothing about parallel-safety or the availability of suitable paths.
+ */
+#define GROUPING_CAN_USE_SORT       0x0001
+#define GROUPING_CAN_USE_HASH       0x0002
+#define GROUPING_CAN_PARTIAL_AGG	0x0004
+
+/*
+ * What kind of partitionwise aggregation is in use?
+ *
+ * PARTITIONWISE_AGGREGATE_NONE: Not used.
+ *
+ * PARTITIONWISE_AGGREGATE_FULL: Aggregate each partition separately, and
+ * append the results.
+ *
+ * PARTITIONWISE_AGGREGATE_PARTIAL: Partially aggregate each partition
+ * separately, append the results, and then finalize aggregation.
+ */
+typedef enum
+{
+	PARTITIONWISE_AGGREGATE_NONE,
+	PARTITIONWISE_AGGREGATE_FULL,
+	PARTITIONWISE_AGGREGATE_PARTIAL
+} PartitionwiseAggregateType;
+
+/*
+ * Struct for extra information passed to subroutines of create_grouping_paths
+ *
+ * flags indicating what kinds of grouping are possible.
+ * partial_costs_set is true if the agg_partial_costs and agg_final_costs
+ * 		have been initialized.
+ * agg_partial_costs gives partial aggregation costs.
+ * agg_final_costs gives finalization costs.
+ * target_parallel_safe is true if target is parallel safe.
+ * havingQual gives list of quals to be applied after aggregation.
+ * targetList gives list of columns to be projected.
+ * patype is the type of partitionwise aggregation that is being performed.
+ */
+typedef struct
+{
+	/* Data which remains constant once set. */
+	int			flags;
+	bool		partial_costs_set;
+	AggClauseCosts agg_partial_costs;
+	AggClauseCosts agg_final_costs;
+
+	/* Data which may differ across partitions. */
+	bool		target_parallel_safe;
+	Node	   *havingQual;
+	List	   *targetList;
+	PartitionwiseAggregateType patype;
+} GroupPathExtraData;
+
+/*
+ * Struct for extra information passed to subroutines of grouping_planner
+ *
+ * limit_needed is true if we actually need a Limit plan node.
+ * limit_tuples is an estimated bound on the number of output tuples,
+ *		or -1 if no LIMIT or couldn't estimate.
+ * count_est and offset_est are the estimated values of the LIMIT and OFFSET
+ * 		expressions computed by preprocess_limit() (see comments for
+ * 		preprocess_limit() for more information).
+ */
+typedef struct
+{
+	bool		limit_needed;
+	double		limit_tuples;
+	int64		count_est;
+	int64		offset_est;
+} FinalPathExtraData;
+
+/*
+ * For speed reasons, cost estimation for join paths is performed in two
+ * phases: the first phase tries to quickly derive a lower bound for the
+ * join cost, and then we check if that's sufficient to reject the path.
+ * If not, we come back for a more refined cost estimate.  The first phase
+ * fills a JoinCostWorkspace struct with its preliminary cost estimates
+ * and possibly additional intermediate values.  The second phase takes
+ * these values as inputs to avoid repeating work.
+ *
+ * (Ideally we'd declare this in cost.h, but it's also needed in pathnode.h,
+ * so seems best to put it here.)
+ */
+typedef struct JoinCostWorkspace
+{
+	/* Preliminary cost estimates --- must not be larger than final ones! */
+	Cost		startup_cost;	/* cost expended before fetching any tuples */
+	Cost		total_cost;		/* total cost (assuming all tuples fetched) */
+
+	/* Fields below here should be treated as private to costsize.c */
+	Cost		run_cost;		/* non-startup cost components */
+
+	/* private for cost_nestloop code */
+	Cost		inner_run_cost; /* also used by cost_mergejoin code */
+	Cost		inner_rescan_run_cost;
+
+	/* private for cost_mergejoin code */
+	double		outer_rows;
+	double		inner_rows;
+	double		outer_skip_rows;
+	double		inner_skip_rows;
+
+	/* private for cost_hashjoin code */
+	int			numbuckets;
+	int			numbatches;
+	double		inner_rows_total;
+} JoinCostWorkspace;
+
+/*
+ * AggInfo holds information about an aggregate that needs to be computed.
+ * Multiple Aggrefs in a query can refer to the same AggInfo by having the
+ * same 'aggno' value, so that the aggregate is computed only once.
+ */
+typedef struct AggInfo
+{
+	/*
+	 * Link to an Aggref expr this state value is for.
+	 *
+	 * There can be multiple identical Aggref's sharing the same per-agg. This
+	 * points to the first one of them.
+	 */
+	Aggref	   *representative_aggref;
+
+	int			transno;
+
+	/*
+	 * "shareable" is false if this agg cannot share state values with other
+	 * aggregates because the final function is read-write.
+	 */
+	bool		shareable;
+
+	/* Oid of the final function or InvalidOid */
+	Oid			finalfn_oid;
+
+} AggInfo;
+
+/*
+ * AggTransInfo holds information about transition state that is used by one
+ * or more aggregates in the query.  Multiple aggregates can share the same
+ * transition state, if they have the same inputs and the same transition
+ * function.  Aggrefs that share the same transition info have the same
+ * 'aggtransno' value.
+ */
+typedef struct AggTransInfo
+{
+	List	   *args;
+	Expr	   *aggfilter;
+
+	/* Oid of the state transition function */
+	Oid			transfn_oid;
+
+	/* Oid of the serialization function or InvalidOid */
+	Oid			serialfn_oid;
+
+	/* Oid of the deserialization function or InvalidOid */
+	Oid			deserialfn_oid;
+
+	/* Oid of the combine function or InvalidOid */
+	Oid			combinefn_oid;
+
+	/* Oid of state value's datatype */
+	Oid			aggtranstype;
+	int32		aggtranstypmod;
+	int			transtypeLen;
+	bool		transtypeByVal;
+	int32		aggtransspace;
+
+	/*
+	 * initial value from pg_aggregate entry
+	 */
+	Datum		initValue;
+	bool		initValueIsNull;
+
+} AggTransInfo;
+
+#endif							/* PATHNODES_H */