Adding upstream version 14.5.upstream/14.5upstream

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

1 files changed, 1584 insertions, 0 deletions

diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
new file mode 100644
index 0000000..9ae851d
--- /dev/null
+++ b/src/include/nodes/primnodes.h
@@ -0,0 +1,1584 @@
+/*-------------------------------------------------------------------------
+ *
+ * primnodes.h
+ *	  Definitions for "primitive" node types, those that are used in more
+ *	  than one of the parse/plan/execute stages of the query pipeline.
+ *	  Currently, these are mostly nodes for executable expressions
+ *	  and join trees.
+ *
+ *
+ * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/nodes/primnodes.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef PRIMNODES_H
+#define PRIMNODES_H
+
+#include "access/attnum.h"
+#include "nodes/bitmapset.h"
+#include "nodes/pg_list.h"
+
+
+/* ----------------------------------------------------------------
+ *						node definitions
+ * ----------------------------------------------------------------
+ */
+
+/*
+ * Alias -
+ *	  specifies an alias for a range variable; the alias might also
+ *	  specify renaming of columns within the table.
+ *
+ * Note: colnames is a list of Value nodes (always strings).  In Alias structs
+ * associated with RTEs, there may be entries corresponding to dropped
+ * columns; these are normally empty strings ("").  See parsenodes.h for info.
+ */
+typedef struct Alias
+{
+	NodeTag		type;
+	char	   *aliasname;		/* aliased rel name (never qualified) */
+	List	   *colnames;		/* optional list of column aliases */
+} Alias;
+
+/* What to do at commit time for temporary relations */
+typedef enum OnCommitAction
+{
+	ONCOMMIT_NOOP,				/* No ON COMMIT clause (do nothing) */
+	ONCOMMIT_PRESERVE_ROWS,		/* ON COMMIT PRESERVE ROWS (do nothing) */
+	ONCOMMIT_DELETE_ROWS,		/* ON COMMIT DELETE ROWS */
+	ONCOMMIT_DROP				/* ON COMMIT DROP */
+} OnCommitAction;
+
+/*
+ * RangeVar - range variable, used in FROM clauses
+ *
+ * Also used to represent table names in utility statements; there, the alias
+ * field is not used, and inh tells whether to apply the operation
+ * recursively to child tables.  In some contexts it is also useful to carry
+ * a TEMP table indication here.
+ */
+typedef struct RangeVar
+{
+	NodeTag		type;
+	char	   *catalogname;	/* the catalog (database) name, or NULL */
+	char	   *schemaname;		/* the schema name, or NULL */
+	char	   *relname;		/* the relation/sequence name */
+	bool		inh;			/* expand rel by inheritance? recursively act
+								 * on children? */
+	char		relpersistence; /* see RELPERSISTENCE_* in pg_class.h */
+	Alias	   *alias;			/* table alias & optional column aliases */
+	int			location;		/* token location, or -1 if unknown */
+} RangeVar;
+
+/*
+ * TableFunc - node for a table function, such as XMLTABLE.
+ *
+ * Entries in the ns_names list are either string Value nodes containing
+ * literal namespace names, or NULL pointers to represent DEFAULT.
+ */
+typedef struct TableFunc
+{
+	NodeTag		type;
+	List	   *ns_uris;		/* list of namespace URI expressions */
+	List	   *ns_names;		/* list of namespace names or NULL */
+	Node	   *docexpr;		/* input document expression */
+	Node	   *rowexpr;		/* row filter expression */
+	List	   *colnames;		/* column names (list of String) */
+	List	   *coltypes;		/* OID list of column type OIDs */
+	List	   *coltypmods;		/* integer list of column typmods */
+	List	   *colcollations;	/* OID list of column collation OIDs */
+	List	   *colexprs;		/* list of column filter expressions */
+	List	   *coldefexprs;	/* list of column default expressions */
+	Bitmapset  *notnulls;		/* nullability flag for each output column */
+	int			ordinalitycol;	/* counts from 0; -1 if none specified */
+	int			location;		/* token location, or -1 if unknown */
+} TableFunc;
+
+/*
+ * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
+ * CREATE MATERIALIZED VIEW
+ *
+ * For CREATE MATERIALIZED VIEW, viewQuery is the parsed-but-not-rewritten
+ * SELECT Query for the view; otherwise it's NULL.  (Although it's actually
+ * Query*, we declare it as Node* to avoid a forward reference.)
+ */
+typedef struct IntoClause
+{
+	NodeTag		type;
+
+	RangeVar   *rel;			/* target relation name */
+	List	   *colNames;		/* column names to assign, or NIL */
+	char	   *accessMethod;	/* table access method */
+	List	   *options;		/* options from WITH clause */
+	OnCommitAction onCommit;	/* what do we do at COMMIT? */
+	char	   *tableSpaceName; /* table space to use, or NULL */
+	Node	   *viewQuery;		/* materialized view's SELECT query */
+	bool		skipData;		/* true for WITH NO DATA */
+} IntoClause;
+
+
+/* ----------------------------------------------------------------
+ *					node types for executable expressions
+ * ----------------------------------------------------------------
+ */
+
+/*
+ * Expr - generic superclass for executable-expression nodes
+ *
+ * All node types that are used in executable expression trees should derive
+ * from Expr (that is, have Expr as their first field).  Since Expr only
+ * contains NodeTag, this is a formality, but it is an easy form of
+ * documentation.  See also the ExprState node types in execnodes.h.
+ */
+typedef struct Expr
+{
+	NodeTag		type;
+} Expr;
+
+/*
+ * Var - expression node representing a variable (ie, a table column)
+ *
+ * In the parser and planner, varno and varattno identify the semantic
+ * referent, which is a base-relation column unless the reference is to a join
+ * USING column that isn't semantically equivalent to either join input column
+ * (because it is a FULL join or the input column requires a type coercion).
+ * In those cases varno and varattno refer to the JOIN RTE.  (Early in the
+ * planner, we replace such join references by the implied expression; but up
+ * till then we want join reference Vars to keep their original identity for
+ * query-printing purposes.)
+ *
+ * At the end of planning, Var nodes appearing in upper-level plan nodes are
+ * reassigned to point to the outputs of their subplans; for example, in a
+ * join node varno becomes INNER_VAR or OUTER_VAR and varattno becomes the
+ * index of the proper element of that subplan's target list.  Similarly,
+ * INDEX_VAR is used to identify Vars that reference an index column rather
+ * than a heap column.  (In ForeignScan and CustomScan plan nodes, INDEX_VAR
+ * is abused to signify references to columns of a custom scan tuple type.)
+ *
+ * ROWID_VAR is used in the planner to identify nonce variables that carry
+ * row identity information during UPDATE/DELETE.  This value should never
+ * be seen outside the planner.
+ *
+ * In the parser, varnosyn and varattnosyn are either identical to
+ * varno/varattno, or they specify the column's position in an aliased JOIN
+ * RTE that hides the semantic referent RTE's refname.  This is a syntactic
+ * identifier as opposed to the semantic identifier; it tells ruleutils.c
+ * how to print the Var properly.  varnosyn/varattnosyn retain their values
+ * throughout planning and execution, so they are particularly helpful to
+ * identify Vars when debugging.  Note, however, that a Var that is generated
+ * in the planner and doesn't correspond to any simple relation column may
+ * have varnosyn = varattnosyn = 0.
+ */
+#define    INNER_VAR		65000	/* reference to inner subplan */
+#define    OUTER_VAR		65001	/* reference to outer subplan */
+#define    INDEX_VAR		65002	/* reference to index column */
+#define    ROWID_VAR		65003	/* row identity column during planning */
+
+#define IS_SPECIAL_VARNO(varno)		((varno) >= INNER_VAR)
+
+/* Symbols for the indexes of the special RTE entries in rules */
+#define    PRS2_OLD_VARNO			1
+#define    PRS2_NEW_VARNO			2
+
+typedef struct Var
+{
+	Expr		xpr;
+	Index		varno;			/* index of this var's relation in the range
+								 * table, or INNER_VAR/OUTER_VAR/INDEX_VAR */
+	AttrNumber	varattno;		/* attribute number of this var, or zero for
+								 * all attrs ("whole-row Var") */
+	Oid			vartype;		/* pg_type OID for the type of this var */
+	int32		vartypmod;		/* pg_attribute typmod value */
+	Oid			varcollid;		/* OID of collation, or InvalidOid if none */
+	Index		varlevelsup;	/* for subquery variables referencing outer
+								 * relations; 0 in a normal var, >0 means N
+								 * levels up */
+	Index		varnosyn;		/* syntactic relation index (0 if unknown) */
+	AttrNumber	varattnosyn;	/* syntactic attribute number */
+	int			location;		/* token location, or -1 if unknown */
+} Var;
+
+/*
+ * Const
+ *
+ * Note: for varlena data types, we make a rule that a Const node's value
+ * must be in non-extended form (4-byte header, no compression or external
+ * references).  This ensures that the Const node is self-contained and makes
+ * it more likely that equal() will see logically identical values as equal.
+ */
+typedef struct Const
+{
+	Expr		xpr;
+	Oid			consttype;		/* pg_type OID of the constant's datatype */
+	int32		consttypmod;	/* typmod value, if any */
+	Oid			constcollid;	/* OID of collation, or InvalidOid if none */
+	int			constlen;		/* typlen of the constant's datatype */
+	Datum		constvalue;		/* the constant's value */
+	bool		constisnull;	/* whether the constant is null (if true,
+								 * constvalue is undefined) */
+	bool		constbyval;		/* whether this datatype is passed by value.
+								 * If true, then all the information is stored
+								 * in the Datum. If false, then the Datum
+								 * contains a pointer to the information. */
+	int			location;		/* token location, or -1 if unknown */
+} Const;
+
+/*
+ * Param
+ *
+ *		paramkind specifies the kind of parameter. The possible values
+ *		for this field are:
+ *
+ *		PARAM_EXTERN:  The parameter value is supplied from outside the plan.
+ *				Such parameters are numbered from 1 to n.
+ *
+ *		PARAM_EXEC:  The parameter is an internal executor parameter, used
+ *				for passing values into and out of sub-queries or from
+ *				nestloop joins to their inner scans.
+ *				For historical reasons, such parameters are numbered from 0.
+ *				These numbers are independent of PARAM_EXTERN numbers.
+ *
+ *		PARAM_SUBLINK:	The parameter represents an output column of a SubLink
+ *				node's sub-select.  The column number is contained in the
+ *				`paramid' field.  (This type of Param is converted to
+ *				PARAM_EXEC during planning.)
+ *
+ *		PARAM_MULTIEXPR:  Like PARAM_SUBLINK, the parameter represents an
+ *				output column of a SubLink node's sub-select, but here, the
+ *				SubLink is always a MULTIEXPR SubLink.  The high-order 16 bits
+ *				of the `paramid' field contain the SubLink's subLinkId, and
+ *				the low-order 16 bits contain the column number.  (This type
+ *				of Param is also converted to PARAM_EXEC during planning.)
+ */
+typedef enum ParamKind
+{
+	PARAM_EXTERN,
+	PARAM_EXEC,
+	PARAM_SUBLINK,
+	PARAM_MULTIEXPR
+} ParamKind;
+
+typedef struct Param
+{
+	Expr		xpr;
+	ParamKind	paramkind;		/* kind of parameter. See above */
+	int			paramid;		/* numeric ID for parameter */
+	Oid			paramtype;		/* pg_type OID of parameter's datatype */
+	int32		paramtypmod;	/* typmod value, if known */
+	Oid			paramcollid;	/* OID of collation, or InvalidOid if none */
+	int			location;		/* token location, or -1 if unknown */
+} Param;
+
+/*
+ * Aggref
+ *
+ * The aggregate's args list is a targetlist, ie, a list of TargetEntry nodes.
+ *
+ * For a normal (non-ordered-set) aggregate, the non-resjunk TargetEntries
+ * represent the aggregate's regular arguments (if any) and resjunk TLEs can
+ * be added at the end to represent ORDER BY expressions that are not also
+ * arguments.  As in a top-level Query, the TLEs can be marked with
+ * ressortgroupref indexes to let them be referenced by SortGroupClause
+ * entries in the aggorder and/or aggdistinct lists.  This represents ORDER BY
+ * and DISTINCT operations to be applied to the aggregate input rows before
+ * they are passed to the transition function.  The grammar only allows a
+ * simple "DISTINCT" specifier for the arguments, but we use the full
+ * query-level representation to allow more code sharing.
+ *
+ * For an ordered-set aggregate, the args list represents the WITHIN GROUP
+ * (aggregated) arguments, all of which will be listed in the aggorder list.
+ * DISTINCT is not supported in this case, so aggdistinct will be NIL.
+ * The direct arguments appear in aggdirectargs (as a list of plain
+ * expressions, not TargetEntry nodes).
+ *
+ * aggtranstype is the data type of the state transition values for this
+ * aggregate (resolved to an actual type, if agg's transtype is polymorphic).
+ * This is determined during planning and is InvalidOid before that.
+ *
+ * aggargtypes is an OID list of the data types of the direct and regular
+ * arguments.  Normally it's redundant with the aggdirectargs and args lists,
+ * but in a combining aggregate, it's not because the args list has been
+ * replaced with a single argument representing the partial-aggregate
+ * transition values.
+ *
+ * aggsplit indicates the expected partial-aggregation mode for the Aggref's
+ * parent plan node.  It's always set to AGGSPLIT_SIMPLE in the parser, but
+ * the planner might change it to something else.  We use this mainly as
+ * a crosscheck that the Aggrefs match the plan; but note that when aggsplit
+ * indicates a non-final mode, aggtype reflects the transition data type
+ * not the SQL-level output type of the aggregate.
+ *
+ * aggno and aggtransno are -1 in the parse stage, and are set in planning.
+ * Aggregates with the same 'aggno' represent the same aggregate expression,
+ * and can share the result.  Aggregates with same 'transno' but different
+ * 'aggno' can share the same transition state, only the final function needs
+ * to be called separately.
+ */
+typedef struct Aggref
+{
+	Expr		xpr;
+	Oid			aggfnoid;		/* pg_proc Oid of the aggregate */
+	Oid			aggtype;		/* type Oid of result of the aggregate */
+	Oid			aggcollid;		/* OID of collation of result */
+	Oid			inputcollid;	/* OID of collation that function should use */
+	Oid			aggtranstype;	/* type Oid of aggregate's transition value */
+	List	   *aggargtypes;	/* type Oids of direct and aggregated args */
+	List	   *aggdirectargs;	/* direct arguments, if an ordered-set agg */
+	List	   *args;			/* aggregated arguments and sort expressions */
+	List	   *aggorder;		/* ORDER BY (list of SortGroupClause) */
+	List	   *aggdistinct;	/* DISTINCT (list of SortGroupClause) */
+	Expr	   *aggfilter;		/* FILTER expression, if any */
+	bool		aggstar;		/* true if argument list was really '*' */
+	bool		aggvariadic;	/* true if variadic arguments have been
+								 * combined into an array last argument */
+	char		aggkind;		/* aggregate kind (see pg_aggregate.h) */
+	Index		agglevelsup;	/* > 0 if agg belongs to outer query */
+	AggSplit	aggsplit;		/* expected agg-splitting mode of parent Agg */
+	int			aggno;			/* unique ID within the Agg node */
+	int			aggtransno;		/* unique ID of transition state in the Agg */
+	int			location;		/* token location, or -1 if unknown */
+} Aggref;
+
+/*
+ * GroupingFunc
+ *
+ * A GroupingFunc is a GROUPING(...) expression, which behaves in many ways
+ * like an aggregate function (e.g. it "belongs" to a specific query level,
+ * which might not be the one immediately containing it), but also differs in
+ * an important respect: it never evaluates its arguments, they merely
+ * designate expressions from the GROUP BY clause of the query level to which
+ * it belongs.
+ *
+ * The spec defines the evaluation of GROUPING() purely by syntactic
+ * replacement, but we make it a real expression for optimization purposes so
+ * that one Agg node can handle multiple grouping sets at once.  Evaluating the
+ * result only needs the column positions to check against the grouping set
+ * being projected.  However, for EXPLAIN to produce meaningful output, we have
+ * to keep the original expressions around, since expression deparse does not
+ * give us any feasible way to get at the GROUP BY clause.
+ *
+ * Also, we treat two GroupingFunc nodes as equal if they have equal arguments
+ * lists and agglevelsup, without comparing the refs and cols annotations.
+ *
+ * In raw parse output we have only the args list; parse analysis fills in the
+ * refs list, and the planner fills in the cols list.
+ */
+typedef struct GroupingFunc
+{
+	Expr		xpr;
+	List	   *args;			/* arguments, not evaluated but kept for
+								 * benefit of EXPLAIN etc. */
+	List	   *refs;			/* ressortgrouprefs of arguments */
+	List	   *cols;			/* actual column positions set by planner */
+	Index		agglevelsup;	/* same as Aggref.agglevelsup */
+	int			location;		/* token location */
+} GroupingFunc;
+
+/*
+ * WindowFunc
+ */
+typedef struct WindowFunc
+{
+	Expr		xpr;
+	Oid			winfnoid;		/* pg_proc Oid of the function */
+	Oid			wintype;		/* type Oid of result of the window function */
+	Oid			wincollid;		/* OID of collation of result */
+	Oid			inputcollid;	/* OID of collation that function should use */
+	List	   *args;			/* arguments to the window function */
+	Expr	   *aggfilter;		/* FILTER expression, if any */
+	Index		winref;			/* index of associated WindowClause */
+	bool		winstar;		/* true if argument list was really '*' */
+	bool		winagg;			/* is function a simple aggregate? */
+	int			location;		/* token location, or -1 if unknown */
+} WindowFunc;
+
+/*
+ * SubscriptingRef: describes a subscripting operation over a container
+ * (array, etc).
+ *
+ * A SubscriptingRef can describe fetching a single element from a container,
+ * fetching a part of a container (e.g. an array slice), storing a single
+ * element into a container, or storing a slice.  The "store" cases work with
+ * an initial container value and a source value that is inserted into the
+ * appropriate part of the container; the result of the operation is an
+ * entire new modified container value.
+ *
+ * If reflowerindexpr = NIL, then we are fetching or storing a single container
+ * element at the subscripts given by refupperindexpr. Otherwise we are
+ * fetching or storing a container slice, that is a rectangular subcontainer
+ * with lower and upper bounds given by the index expressions.
+ * reflowerindexpr must be the same length as refupperindexpr when it
+ * is not NIL.
+ *
+ * In the slice case, individual expressions in the subscript lists can be
+ * NULL, meaning "substitute the array's current lower or upper bound".
+ * (Non-array containers may or may not support this.)
+ *
+ * refcontainertype is the actual container type that determines the
+ * subscripting semantics.  (This will generally be either the exposed type of
+ * refexpr, or the base type if that is a domain.)  refelemtype is the type of
+ * the container's elements; this is saved for the use of the subscripting
+ * functions, but is not used by the core code.  refrestype, reftypmod, and
+ * refcollid describe the type of the SubscriptingRef's result.  In a store
+ * expression, refrestype will always match refcontainertype; in a fetch,
+ * it could be refelemtype for an element fetch, or refcontainertype for a
+ * slice fetch, or possibly something else as determined by type-specific
+ * subscripting logic.  Likewise, reftypmod and refcollid will match the
+ * container's properties in a store, but could be different in a fetch.
+ *
+ * Note: for the cases where a container is returned, if refexpr yields a R/W
+ * expanded container, then the implementation is allowed to modify that
+ * object in-place and return the same object.
+ */
+typedef struct SubscriptingRef
+{
+	Expr		xpr;
+	Oid			refcontainertype;	/* type of the container proper */
+	Oid			refelemtype;	/* the container type's pg_type.typelem */
+	Oid			refrestype;		/* type of the SubscriptingRef's result */
+	int32		reftypmod;		/* typmod of the result */
+	Oid			refcollid;		/* collation of result, or InvalidOid if none */
+	List	   *refupperindexpr;	/* expressions that evaluate to upper
+									 * container indexes */
+	List	   *reflowerindexpr;	/* expressions that evaluate to lower
+									 * container indexes, or NIL for single
+									 * container element */
+	Expr	   *refexpr;		/* the expression that evaluates to a
+								 * container value */
+	Expr	   *refassgnexpr;	/* expression for the source value, or NULL if
+								 * fetch */
+} SubscriptingRef;
+
+/*
+ * CoercionContext - distinguishes the allowed set of type casts
+ *
+ * NB: ordering of the alternatives is significant; later (larger) values
+ * allow more casts than earlier ones.
+ */
+typedef enum CoercionContext
+{
+	COERCION_IMPLICIT,			/* coercion in context of expression */
+	COERCION_ASSIGNMENT,		/* coercion in context of assignment */
+	COERCION_PLPGSQL,			/* if no assignment cast, use CoerceViaIO */
+	COERCION_EXPLICIT			/* explicit cast operation */
+} CoercionContext;
+
+/*
+ * CoercionForm - how to display a FuncExpr or related node
+ *
+ * "Coercion" is a bit of a misnomer, since this value records other
+ * special syntaxes besides casts, but for now we'll keep this naming.
+ *
+ * NB: equal() ignores CoercionForm fields, therefore this *must* not carry
+ * any semantically significant information.  We need that behavior so that
+ * the planner will consider equivalent implicit and explicit casts to be
+ * equivalent.  In cases where those actually behave differently, the coercion
+ * function's arguments will be different.
+ */
+typedef enum CoercionForm
+{
+	COERCE_EXPLICIT_CALL,		/* display as a function call */
+	COERCE_EXPLICIT_CAST,		/* display as an explicit cast */
+	COERCE_IMPLICIT_CAST,		/* implicit cast, so hide it */
+	COERCE_SQL_SYNTAX			/* display with SQL-mandated special syntax */
+} CoercionForm;
+
+/*
+ * FuncExpr - expression node for a function call
+ */
+typedef struct FuncExpr
+{
+	Expr		xpr;
+	Oid			funcid;			/* PG_PROC OID of the function */
+	Oid			funcresulttype; /* PG_TYPE OID of result value */
+	bool		funcretset;		/* true if function returns set */
+	bool		funcvariadic;	/* true if variadic arguments have been
+								 * combined into an array last argument */
+	CoercionForm funcformat;	/* how to display this function call */
+	Oid			funccollid;		/* OID of collation of result */
+	Oid			inputcollid;	/* OID of collation that function should use */
+	List	   *args;			/* arguments to the function */
+	int			location;		/* token location, or -1 if unknown */
+} FuncExpr;
+
+/*
+ * NamedArgExpr - a named argument of a function
+ *
+ * This node type can only appear in the args list of a FuncCall or FuncExpr
+ * node.  We support pure positional call notation (no named arguments),
+ * named notation (all arguments are named), and mixed notation (unnamed
+ * arguments followed by named ones).
+ *
+ * Parse analysis sets argnumber to the positional index of the argument,
+ * but doesn't rearrange the argument list.
+ *
+ * The planner will convert argument lists to pure positional notation
+ * during expression preprocessing, so execution never sees a NamedArgExpr.
+ */
+typedef struct NamedArgExpr
+{
+	Expr		xpr;
+	Expr	   *arg;			/* the argument expression */
+	char	   *name;			/* the name */
+	int			argnumber;		/* argument's number in positional notation */
+	int			location;		/* argument name location, or -1 if unknown */
+} NamedArgExpr;
+
+/*
+ * OpExpr - expression node for an operator invocation
+ *
+ * Semantically, this is essentially the same as a function call.
+ *
+ * Note that opfuncid is not necessarily filled in immediately on creation
+ * of the node.  The planner makes sure it is valid before passing the node
+ * tree to the executor, but during parsing/planning opfuncid can be 0.
+ */
+typedef struct OpExpr
+{
+	Expr		xpr;
+	Oid			opno;			/* PG_OPERATOR OID of the operator */
+	Oid			opfuncid;		/* PG_PROC OID of underlying function */
+	Oid			opresulttype;	/* PG_TYPE OID of result value */
+	bool		opretset;		/* true if operator returns set */
+	Oid			opcollid;		/* OID of collation of result */
+	Oid			inputcollid;	/* OID of collation that operator should use */
+	List	   *args;			/* arguments to the operator (1 or 2) */
+	int			location;		/* token location, or -1 if unknown */
+} OpExpr;
+
+/*
+ * DistinctExpr - expression node for "x IS DISTINCT FROM y"
+ *
+ * Except for the nodetag, this is represented identically to an OpExpr
+ * referencing the "=" operator for x and y.
+ * We use "=", not the more obvious "<>", because more datatypes have "="
+ * than "<>".  This means the executor must invert the operator result.
+ * Note that the operator function won't be called at all if either input
+ * is NULL, since then the result can be determined directly.
+ */
+typedef OpExpr DistinctExpr;
+
+/*
+ * NullIfExpr - a NULLIF expression
+ *
+ * Like DistinctExpr, this is represented the same as an OpExpr referencing
+ * the "=" operator for x and y.
+ */
+typedef OpExpr NullIfExpr;
+
+/*
+ * ScalarArrayOpExpr - expression node for "scalar op ANY/ALL (array)"
+ *
+ * The operator must yield boolean.  It is applied to the left operand
+ * and each element of the righthand array, and the results are combined
+ * with OR or AND (for ANY or ALL respectively).  The node representation
+ * is almost the same as for the underlying operator, but we need a useOr
+ * flag to remember whether it's ANY or ALL, and we don't have to store
+ * the result type (or the collation) because it must be boolean.
+ *
+ * A ScalarArrayOpExpr with a valid hashfuncid is evaluated during execution
+ * by building a hash table containing the Const values from the rhs arg.
+ * This table is probed during expression evaluation.  Only useOr=true
+ * ScalarArrayOpExpr with Const arrays on the rhs can have the hashfuncid
+ * field set. See convert_saop_to_hashed_saop().
+ */
+typedef struct ScalarArrayOpExpr
+{
+	Expr		xpr;
+	Oid			opno;			/* PG_OPERATOR OID of the operator */
+	Oid			opfuncid;		/* PG_PROC OID of comparison function */
+	Oid			hashfuncid;		/* PG_PROC OID of hash func or InvalidOid */
+	bool		useOr;			/* true for ANY, false for ALL */
+	Oid			inputcollid;	/* OID of collation that operator should use */
+	List	   *args;			/* the scalar and array operands */
+	int			location;		/* token location, or -1 if unknown */
+} ScalarArrayOpExpr;
+
+/*
+ * BoolExpr - expression node for the basic Boolean operators AND, OR, NOT
+ *
+ * Notice the arguments are given as a List.  For NOT, of course the list
+ * must always have exactly one element.  For AND and OR, there can be two
+ * or more arguments.
+ */
+typedef enum BoolExprType
+{
+	AND_EXPR, OR_EXPR, NOT_EXPR
+} BoolExprType;
+
+typedef struct BoolExpr
+{
+	Expr		xpr;
+	BoolExprType boolop;
+	List	   *args;			/* arguments to this expression */
+	int			location;		/* token location, or -1 if unknown */
+} BoolExpr;
+
+/*
+ * SubLink
+ *
+ * A SubLink represents a subselect appearing in an expression, and in some
+ * cases also the combining operator(s) just above it.  The subLinkType
+ * indicates the form of the expression represented:
+ *	EXISTS_SUBLINK		EXISTS(SELECT ...)
+ *	ALL_SUBLINK			(lefthand) op ALL (SELECT ...)
+ *	ANY_SUBLINK			(lefthand) op ANY (SELECT ...)
+ *	ROWCOMPARE_SUBLINK	(lefthand) op (SELECT ...)
+ *	EXPR_SUBLINK		(SELECT with single targetlist item ...)
+ *	MULTIEXPR_SUBLINK	(SELECT with multiple targetlist items ...)
+ *	ARRAY_SUBLINK		ARRAY(SELECT with single targetlist item ...)
+ *	CTE_SUBLINK			WITH query (never actually part of an expression)
+ * For ALL, ANY, and ROWCOMPARE, the lefthand is a list of expressions of the
+ * same length as the subselect's targetlist.  ROWCOMPARE will *always* have
+ * a list with more than one entry; if the subselect has just one target
+ * then the parser will create an EXPR_SUBLINK instead (and any operator
+ * above the subselect will be represented separately).
+ * ROWCOMPARE, EXPR, and MULTIEXPR require the subselect to deliver at most
+ * one row (if it returns no rows, the result is NULL).
+ * ALL, ANY, and ROWCOMPARE require the combining operators to deliver boolean
+ * results.  ALL and ANY combine the per-row results using AND and OR
+ * semantics respectively.
+ * ARRAY requires just one target column, and creates an array of the target
+ * column's type using any number of rows resulting from the subselect.
+ *
+ * SubLink is classed as an Expr node, but it is not actually executable;
+ * it must be replaced in the expression tree by a SubPlan node during
+ * planning.
+ *
+ * NOTE: in the raw output of gram.y, testexpr contains just the raw form
+ * of the lefthand expression (if any), and operName is the String name of
+ * the combining operator.  Also, subselect is a raw parsetree.  During parse
+ * analysis, the parser transforms testexpr into a complete boolean expression
+ * that compares the lefthand value(s) to PARAM_SUBLINK nodes representing the
+ * output columns of the subselect.  And subselect is transformed to a Query.
+ * This is the representation seen in saved rules and in the rewriter.
+ *
+ * In EXISTS, EXPR, MULTIEXPR, and ARRAY SubLinks, testexpr and operName
+ * are unused and are always null.
+ *
+ * subLinkId is currently used only for MULTIEXPR SubLinks, and is zero in
+ * other SubLinks.  This number identifies different multiple-assignment
+ * subqueries within an UPDATE statement's SET list.  It is unique only
+ * within a particular targetlist.  The output column(s) of the MULTIEXPR
+ * are referenced by PARAM_MULTIEXPR Params appearing elsewhere in the tlist.
+ *
+ * The CTE_SUBLINK case never occurs in actual SubLink nodes, but it is used
+ * in SubPlans generated for WITH subqueries.
+ */
+typedef enum SubLinkType
+{
+	EXISTS_SUBLINK,
+	ALL_SUBLINK,
+	ANY_SUBLINK,
+	ROWCOMPARE_SUBLINK,
+	EXPR_SUBLINK,
+	MULTIEXPR_SUBLINK,
+	ARRAY_SUBLINK,
+	CTE_SUBLINK					/* for SubPlans only */
+} SubLinkType;
+
+
+typedef struct SubLink
+{
+	Expr		xpr;
+	SubLinkType subLinkType;	/* see above */
+	int			subLinkId;		/* ID (1..n); 0 if not MULTIEXPR */
+	Node	   *testexpr;		/* outer-query test for ALL/ANY/ROWCOMPARE */
+	List	   *operName;		/* originally specified operator name */
+	Node	   *subselect;		/* subselect as Query* or raw parsetree */
+	int			location;		/* token location, or -1 if unknown */
+} SubLink;
+
+/*
+ * SubPlan - executable expression node for a subplan (sub-SELECT)
+ *
+ * The planner replaces SubLink nodes in expression trees with SubPlan
+ * nodes after it has finished planning the subquery.  SubPlan references
+ * a sub-plantree stored in the subplans list of the toplevel PlannedStmt.
+ * (We avoid a direct link to make it easier to copy expression trees
+ * without causing multiple processing of the subplan.)
+ *
+ * In an ordinary subplan, testexpr points to an executable expression
+ * (OpExpr, an AND/OR tree of OpExprs, or RowCompareExpr) for the combining
+ * operator(s); the left-hand arguments are the original lefthand expressions,
+ * and the right-hand arguments are PARAM_EXEC Param nodes representing the
+ * outputs of the sub-select.  (NOTE: runtime coercion functions may be
+ * inserted as well.)  This is just the same expression tree as testexpr in
+ * the original SubLink node, but the PARAM_SUBLINK nodes are replaced by
+ * suitably numbered PARAM_EXEC nodes.
+ *
+ * If the sub-select becomes an initplan rather than a subplan, the executable
+ * expression is part of the outer plan's expression tree (and the SubPlan
+ * node itself is not, but rather is found in the outer plan's initPlan
+ * list).  In this case testexpr is NULL to avoid duplication.
+ *
+ * The planner also derives lists of the values that need to be passed into
+ * and out of the subplan.  Input values are represented as a list "args" of
+ * expressions to be evaluated in the outer-query context (currently these
+ * args are always just Vars, but in principle they could be any expression).
+ * The values are assigned to the global PARAM_EXEC params indexed by parParam
+ * (the parParam and args lists must have the same ordering).  setParam is a
+ * list of the PARAM_EXEC params that are computed by the sub-select, if it
+ * is an initplan; they are listed in order by sub-select output column
+ * position.  (parParam and setParam are integer Lists, not Bitmapsets,
+ * because their ordering is significant.)
+ *
+ * Also, the planner computes startup and per-call costs for use of the
+ * SubPlan.  Note that these include the cost of the subquery proper,
+ * evaluation of the testexpr if any, and any hashtable management overhead.
+ */
+typedef struct SubPlan
+{
+	Expr		xpr;
+	/* Fields copied from original SubLink: */
+	SubLinkType subLinkType;	/* see above */
+	/* The combining operators, transformed to an executable expression: */
+	Node	   *testexpr;		/* OpExpr or RowCompareExpr expression tree */
+	List	   *paramIds;		/* IDs of Params embedded in the above */
+	/* Identification of the Plan tree to use: */
+	int			plan_id;		/* Index (from 1) in PlannedStmt.subplans */
+	/* Identification of the SubPlan for EXPLAIN and debugging purposes: */
+	char	   *plan_name;		/* A name assigned during planning */
+	/* Extra data useful for determining subplan's output type: */
+	Oid			firstColType;	/* Type of first column of subplan result */
+	int32		firstColTypmod; /* Typmod of first column of subplan result */
+	Oid			firstColCollation;	/* Collation of first column of subplan
+									 * result */
+	/* Information about execution strategy: */
+	bool		useHashTable;	/* true to store subselect output in a hash
+								 * table (implies we are doing "IN") */
+	bool		unknownEqFalse; /* true if it's okay to return FALSE when the
+								 * spec result is UNKNOWN; this allows much
+								 * simpler handling of null values */
+	bool		parallel_safe;	/* is the subplan parallel-safe? */
+	/* Note: parallel_safe does not consider contents of testexpr or args */
+	/* Information for passing params into and out of the subselect: */
+	/* setParam and parParam are lists of integers (param IDs) */
+	List	   *setParam;		/* initplan subqueries have to set these
+								 * Params for parent plan */
+	List	   *parParam;		/* indices of input Params from parent plan */
+	List	   *args;			/* exprs to pass as parParam values */
+	/* Estimated execution costs: */
+	Cost		startup_cost;	/* one-time setup cost */
+	Cost		per_call_cost;	/* cost for each subplan evaluation */
+} SubPlan;
+
+/*
+ * AlternativeSubPlan - expression node for a choice among SubPlans
+ *
+ * This is used only transiently during planning: by the time the plan
+ * reaches the executor, all AlternativeSubPlan nodes have been removed.
+ *
+ * The subplans are given as a List so that the node definition need not
+ * change if there's ever more than two alternatives.  For the moment,
+ * though, there are always exactly two; and the first one is the fast-start
+ * plan.
+ */
+typedef struct AlternativeSubPlan
+{
+	Expr		xpr;
+	List	   *subplans;		/* SubPlan(s) with equivalent results */
+} AlternativeSubPlan;
+
+/* ----------------
+ * FieldSelect
+ *
+ * FieldSelect represents the operation of extracting one field from a tuple
+ * value.  At runtime, the input expression is expected to yield a rowtype
+ * Datum.  The specified field number is extracted and returned as a Datum.
+ * ----------------
+ */
+
+typedef struct FieldSelect
+{
+	Expr		xpr;
+	Expr	   *arg;			/* input expression */
+	AttrNumber	fieldnum;		/* attribute number of field to extract */
+	Oid			resulttype;		/* type of the field (result type of this
+								 * node) */
+	int32		resulttypmod;	/* output typmod (usually -1) */
+	Oid			resultcollid;	/* OID of collation of the field */
+} FieldSelect;
+
+/* ----------------
+ * FieldStore
+ *
+ * FieldStore represents the operation of modifying one field in a tuple
+ * value, yielding a new tuple value (the input is not touched!).  Like
+ * the assign case of SubscriptingRef, this is used to implement UPDATE of a
+ * portion of a column.
+ *
+ * resulttype is always a named composite type (not a domain).  To update
+ * a composite domain value, apply CoerceToDomain to the FieldStore.
+ *
+ * A single FieldStore can actually represent updates of several different
+ * fields.  The parser only generates FieldStores with single-element lists,
+ * but the planner will collapse multiple updates of the same base column
+ * into one FieldStore.
+ * ----------------
+ */
+
+typedef struct FieldStore
+{
+	Expr		xpr;
+	Expr	   *arg;			/* input tuple value */
+	List	   *newvals;		/* new value(s) for field(s) */
+	List	   *fieldnums;		/* integer list of field attnums */
+	Oid			resulttype;		/* type of result (same as type of arg) */
+	/* Like RowExpr, we deliberately omit a typmod and collation here */
+} FieldStore;
+
+/* ----------------
+ * RelabelType
+ *
+ * RelabelType represents a "dummy" type coercion between two binary-
+ * compatible datatypes, such as reinterpreting the result of an OID
+ * expression as an int4.  It is a no-op at runtime; we only need it
+ * to provide a place to store the correct type to be attributed to
+ * the expression result during type resolution.  (We can't get away
+ * with just overwriting the type field of the input expression node,
+ * so we need a separate node to show the coercion's result type.)
+ * ----------------
+ */
+
+typedef struct RelabelType
+{
+	Expr		xpr;
+	Expr	   *arg;			/* input expression */
+	Oid			resulttype;		/* output type of coercion expression */
+	int32		resulttypmod;	/* output typmod (usually -1) */
+	Oid			resultcollid;	/* OID of collation, or InvalidOid if none */
+	CoercionForm relabelformat; /* how to display this node */
+	int			location;		/* token location, or -1 if unknown */
+} RelabelType;
+
+/* ----------------
+ * CoerceViaIO
+ *
+ * CoerceViaIO represents a type coercion between two types whose textual
+ * representations are compatible, implemented by invoking the source type's
+ * typoutput function then the destination type's typinput function.
+ * ----------------
+ */
+
+typedef struct CoerceViaIO
+{
+	Expr		xpr;
+	Expr	   *arg;			/* input expression */
+	Oid			resulttype;		/* output type of coercion */
+	/* output typmod is not stored, but is presumed -1 */
+	Oid			resultcollid;	/* OID of collation, or InvalidOid if none */
+	CoercionForm coerceformat;	/* how to display this node */
+	int			location;		/* token location, or -1 if unknown */
+} CoerceViaIO;
+
+/* ----------------
+ * ArrayCoerceExpr
+ *
+ * ArrayCoerceExpr represents a type coercion from one array type to another,
+ * which is implemented by applying the per-element coercion expression
+ * "elemexpr" to each element of the source array.  Within elemexpr, the
+ * source element is represented by a CaseTestExpr node.  Note that even if
+ * elemexpr is a no-op (that is, just CaseTestExpr + RelabelType), the
+ * coercion still requires some effort: we have to fix the element type OID
+ * stored in the array header.
+ * ----------------
+ */
+
+typedef struct ArrayCoerceExpr
+{
+	Expr		xpr;
+	Expr	   *arg;			/* input expression (yields an array) */
+	Expr	   *elemexpr;		/* expression representing per-element work */
+	Oid			resulttype;		/* output type of coercion (an array type) */
+	int32		resulttypmod;	/* output typmod (also element typmod) */
+	Oid			resultcollid;	/* OID of collation, or InvalidOid if none */
+	CoercionForm coerceformat;	/* how to display this node */
+	int			location;		/* token location, or -1 if unknown */
+} ArrayCoerceExpr;
+
+/* ----------------
+ * ConvertRowtypeExpr
+ *
+ * ConvertRowtypeExpr represents a type coercion from one composite type
+ * to another, where the source type is guaranteed to contain all the columns
+ * needed for the destination type plus possibly others; the columns need not
+ * be in the same positions, but are matched up by name.  This is primarily
+ * used to convert a whole-row value of an inheritance child table into a
+ * valid whole-row value of its parent table's rowtype.  Both resulttype
+ * and the exposed type of "arg" must be named composite types (not domains).
+ * ----------------
+ */
+
+typedef struct ConvertRowtypeExpr
+{
+	Expr		xpr;
+	Expr	   *arg;			/* input expression */
+	Oid			resulttype;		/* output type (always a composite type) */
+	/* Like RowExpr, we deliberately omit a typmod and collation here */
+	CoercionForm convertformat; /* how to display this node */
+	int			location;		/* token location, or -1 if unknown */
+} ConvertRowtypeExpr;
+
+/*----------
+ * CollateExpr - COLLATE
+ *
+ * The planner replaces CollateExpr with RelabelType during expression
+ * preprocessing, so execution never sees a CollateExpr.
+ *----------
+ */
+typedef struct CollateExpr
+{
+	Expr		xpr;
+	Expr	   *arg;			/* input expression */
+	Oid			collOid;		/* collation's OID */
+	int			location;		/* token location, or -1 if unknown */
+} CollateExpr;
+
+/*----------
+ * CaseExpr - a CASE expression
+ *
+ * We support two distinct forms of CASE expression:
+ *		CASE WHEN boolexpr THEN expr [ WHEN boolexpr THEN expr ... ]
+ *		CASE testexpr WHEN compexpr THEN expr [ WHEN compexpr THEN expr ... ]
+ * These are distinguishable by the "arg" field being NULL in the first case
+ * and the testexpr in the second case.
+ *
+ * In the raw grammar output for the second form, the condition expressions
+ * of the WHEN clauses are just the comparison values.  Parse analysis
+ * converts these to valid boolean expressions of the form
+ *		CaseTestExpr '=' compexpr
+ * where the CaseTestExpr node is a placeholder that emits the correct
+ * value at runtime.  This structure is used so that the testexpr need be
+ * evaluated only once.  Note that after parse analysis, the condition
+ * expressions always yield boolean.
+ *
+ * Note: we can test whether a CaseExpr has been through parse analysis
+ * yet by checking whether casetype is InvalidOid or not.
+ *----------
+ */
+typedef struct CaseExpr
+{
+	Expr		xpr;
+	Oid			casetype;		/* type of expression result */
+	Oid			casecollid;		/* OID of collation, or InvalidOid if none */
+	Expr	   *arg;			/* implicit equality comparison argument */
+	List	   *args;			/* the arguments (list of WHEN clauses) */
+	Expr	   *defresult;		/* the default result (ELSE clause) */
+	int			location;		/* token location, or -1 if unknown */
+} CaseExpr;
+
+/*
+ * CaseWhen - one arm of a CASE expression
+ */
+typedef struct CaseWhen
+{
+	Expr		xpr;
+	Expr	   *expr;			/* condition expression */
+	Expr	   *result;			/* substitution result */
+	int			location;		/* token location, or -1 if unknown */
+} CaseWhen;
+
+/*
+ * Placeholder node for the test value to be processed by a CASE expression.
+ * This is effectively like a Param, but can be implemented more simply
+ * since we need only one replacement value at a time.
+ *
+ * We also abuse this node type for some other purposes, including:
+ *	* Placeholder for the current array element value in ArrayCoerceExpr;
+ *	  see build_coercion_expression().
+ *	* Nested FieldStore/SubscriptingRef assignment expressions in INSERT/UPDATE;
+ *	  see transformAssignmentIndirection().
+ *
+ * The uses in CaseExpr and ArrayCoerceExpr are safe only to the extent that
+ * there is not any other CaseExpr or ArrayCoerceExpr between the value source
+ * node and its child CaseTestExpr(s).  This is true in the parse analysis
+ * output, but the planner's function-inlining logic has to be careful not to
+ * break it.
+ *
+ * The nested-assignment-expression case is safe because the only node types
+ * that can be above such CaseTestExprs are FieldStore and SubscriptingRef.
+ */
+typedef struct CaseTestExpr
+{
+	Expr		xpr;
+	Oid			typeId;			/* type for substituted value */
+	int32		typeMod;		/* typemod for substituted value */
+	Oid			collation;		/* collation for the substituted value */
+} CaseTestExpr;
+
+/*
+ * ArrayExpr - an ARRAY[] expression
+ *
+ * Note: if multidims is false, the constituent expressions all yield the
+ * scalar type identified by element_typeid.  If multidims is true, the
+ * constituent expressions all yield arrays of element_typeid (ie, the same
+ * type as array_typeid); at runtime we must check for compatible subscripts.
+ */
+typedef struct ArrayExpr
+{
+	Expr		xpr;
+	Oid			array_typeid;	/* type of expression result */
+	Oid			array_collid;	/* OID of collation, or InvalidOid if none */
+	Oid			element_typeid; /* common type of array elements */
+	List	   *elements;		/* the array elements or sub-arrays */
+	bool		multidims;		/* true if elements are sub-arrays */
+	int			location;		/* token location, or -1 if unknown */
+} ArrayExpr;
+
+/*
+ * RowExpr - a ROW() expression
+ *
+ * Note: the list of fields must have a one-for-one correspondence with
+ * physical fields of the associated rowtype, although it is okay for it
+ * to be shorter than the rowtype.  That is, the N'th list element must
+ * match up with the N'th physical field.  When the N'th physical field
+ * is a dropped column (attisdropped) then the N'th list element can just
+ * be a NULL constant.  (This case can only occur for named composite types,
+ * not RECORD types, since those are built from the RowExpr itself rather
+ * than vice versa.)  It is important not to assume that length(args) is
+ * the same as the number of columns logically present in the rowtype.
+ *
+ * colnames provides field names in cases where the names can't easily be
+ * obtained otherwise.  Names *must* be provided if row_typeid is RECORDOID.
+ * If row_typeid identifies a known composite type, colnames can be NIL to
+ * indicate the type's cataloged field names apply.  Note that colnames can
+ * be non-NIL even for a composite type, and typically is when the RowExpr
+ * was created by expanding a whole-row Var.  This is so that we can retain
+ * the column alias names of the RTE that the Var referenced (which would
+ * otherwise be very difficult to extract from the parsetree).  Like the
+ * args list, colnames is one-for-one with physical fields of the rowtype.
+ */
+typedef struct RowExpr
+{
+	Expr		xpr;
+	List	   *args;			/* the fields */
+	Oid			row_typeid;		/* RECORDOID or a composite type's ID */
+
+	/*
+	 * row_typeid cannot be a domain over composite, only plain composite.  To
+	 * create a composite domain value, apply CoerceToDomain to the RowExpr.
+	 *
+	 * Note: we deliberately do NOT store a typmod.  Although a typmod will be
+	 * associated with specific RECORD types at runtime, it will differ for
+	 * different backends, and so cannot safely be stored in stored
+	 * parsetrees.  We must assume typmod -1 for a RowExpr node.
+	 *
+	 * We don't need to store a collation either.  The result type is
+	 * necessarily composite, and composite types never have a collation.
+	 */
+	CoercionForm row_format;	/* how to display this node */
+	List	   *colnames;		/* list of String, or NIL */
+	int			location;		/* token location, or -1 if unknown */
+} RowExpr;
+
+/*
+ * RowCompareExpr - row-wise comparison, such as (a, b) <= (1, 2)
+ *
+ * We support row comparison for any operator that can be determined to
+ * act like =, <>, <, <=, >, or >= (we determine this by looking for the
+ * operator in btree opfamilies).  Note that the same operator name might
+ * map to a different operator for each pair of row elements, since the
+ * element datatypes can vary.
+ *
+ * A RowCompareExpr node is only generated for the < <= > >= cases;
+ * the = and <> cases are translated to simple AND or OR combinations
+ * of the pairwise comparisons.  However, we include = and <> in the
+ * RowCompareType enum for the convenience of parser logic.
+ */
+typedef enum RowCompareType
+{
+	/* Values of this enum are chosen to match btree strategy numbers */
+	ROWCOMPARE_LT = 1,			/* BTLessStrategyNumber */
+	ROWCOMPARE_LE = 2,			/* BTLessEqualStrategyNumber */
+	ROWCOMPARE_EQ = 3,			/* BTEqualStrategyNumber */
+	ROWCOMPARE_GE = 4,			/* BTGreaterEqualStrategyNumber */
+	ROWCOMPARE_GT = 5,			/* BTGreaterStrategyNumber */
+	ROWCOMPARE_NE = 6			/* no such btree strategy */
+} RowCompareType;
+
+typedef struct RowCompareExpr
+{
+	Expr		xpr;
+	RowCompareType rctype;		/* LT LE GE or GT, never EQ or NE */
+	List	   *opnos;			/* OID list of pairwise comparison ops */
+	List	   *opfamilies;		/* OID list of containing operator families */
+	List	   *inputcollids;	/* OID list of collations for comparisons */
+	List	   *largs;			/* the left-hand input arguments */
+	List	   *rargs;			/* the right-hand input arguments */
+} RowCompareExpr;
+
+/*
+ * CoalesceExpr - a COALESCE expression
+ */
+typedef struct CoalesceExpr
+{
+	Expr		xpr;
+	Oid			coalescetype;	/* type of expression result */
+	Oid			coalescecollid; /* OID of collation, or InvalidOid if none */
+	List	   *args;			/* the arguments */
+	int			location;		/* token location, or -1 if unknown */
+} CoalesceExpr;
+
+/*
+ * MinMaxExpr - a GREATEST or LEAST function
+ */
+typedef enum MinMaxOp
+{
+	IS_GREATEST,
+	IS_LEAST
+} MinMaxOp;
+
+typedef struct MinMaxExpr
+{
+	Expr		xpr;
+	Oid			minmaxtype;		/* common type of arguments and result */
+	Oid			minmaxcollid;	/* OID of collation of result */
+	Oid			inputcollid;	/* OID of collation that function should use */
+	MinMaxOp	op;				/* function to execute */
+	List	   *args;			/* the arguments */
+	int			location;		/* token location, or -1 if unknown */
+} MinMaxExpr;
+
+/*
+ * SQLValueFunction - parameterless functions with special grammar productions
+ *
+ * The SQL standard categorizes some of these as <datetime value function>
+ * and others as <general value specification>.  We call 'em SQLValueFunctions
+ * for lack of a better term.  We store type and typmod of the result so that
+ * some code doesn't need to know each function individually, and because
+ * we would need to store typmod anyway for some of the datetime functions.
+ * Note that currently, all variants return non-collating datatypes, so we do
+ * not need a collation field; also, all these functions are stable.
+ */
+typedef enum SQLValueFunctionOp
+{
+	SVFOP_CURRENT_DATE,
+	SVFOP_CURRENT_TIME,
+	SVFOP_CURRENT_TIME_N,
+	SVFOP_CURRENT_TIMESTAMP,
+	SVFOP_CURRENT_TIMESTAMP_N,
+	SVFOP_LOCALTIME,
+	SVFOP_LOCALTIME_N,
+	SVFOP_LOCALTIMESTAMP,
+	SVFOP_LOCALTIMESTAMP_N,
+	SVFOP_CURRENT_ROLE,
+	SVFOP_CURRENT_USER,
+	SVFOP_USER,
+	SVFOP_SESSION_USER,
+	SVFOP_CURRENT_CATALOG,
+	SVFOP_CURRENT_SCHEMA
+} SQLValueFunctionOp;
+
+typedef struct SQLValueFunction
+{
+	Expr		xpr;
+	SQLValueFunctionOp op;		/* which function this is */
+	Oid			type;			/* result type/typmod */
+	int32		typmod;
+	int			location;		/* token location, or -1 if unknown */
+} SQLValueFunction;
+
+/*
+ * XmlExpr - various SQL/XML functions requiring special grammar productions
+ *
+ * 'name' carries the "NAME foo" argument (already XML-escaped).
+ * 'named_args' and 'arg_names' represent an xml_attribute list.
+ * 'args' carries all other arguments.
+ *
+ * Note: result type/typmod/collation are not stored, but can be deduced
+ * from the XmlExprOp.  The type/typmod fields are just used for display
+ * purposes, and are NOT necessarily the true result type of the node.
+ */
+typedef enum XmlExprOp
+{
+	IS_XMLCONCAT,				/* XMLCONCAT(args) */
+	IS_XMLELEMENT,				/* XMLELEMENT(name, xml_attributes, args) */
+	IS_XMLFOREST,				/* XMLFOREST(xml_attributes) */
+	IS_XMLPARSE,				/* XMLPARSE(text, is_doc, preserve_ws) */
+	IS_XMLPI,					/* XMLPI(name [, args]) */
+	IS_XMLROOT,					/* XMLROOT(xml, version, standalone) */
+	IS_XMLSERIALIZE,			/* XMLSERIALIZE(is_document, xmlval) */
+	IS_DOCUMENT					/* xmlval IS DOCUMENT */
+} XmlExprOp;
+
+typedef enum
+{
+	XMLOPTION_DOCUMENT,
+	XMLOPTION_CONTENT
+} XmlOptionType;
+
+typedef struct XmlExpr
+{
+	Expr		xpr;
+	XmlExprOp	op;				/* xml function ID */
+	char	   *name;			/* name in xml(NAME foo ...) syntaxes */
+	List	   *named_args;		/* non-XML expressions for xml_attributes */
+	List	   *arg_names;		/* parallel list of Value strings */
+	List	   *args;			/* list of expressions */
+	XmlOptionType xmloption;	/* DOCUMENT or CONTENT */
+	Oid			type;			/* target type/typmod for XMLSERIALIZE */
+	int32		typmod;
+	int			location;		/* token location, or -1 if unknown */
+} XmlExpr;
+
+/* ----------------
+ * NullTest
+ *
+ * NullTest represents the operation of testing a value for NULLness.
+ * The appropriate test is performed and returned as a boolean Datum.
+ *
+ * When argisrow is false, this simply represents a test for the null value.
+ *
+ * When argisrow is true, the input expression must yield a rowtype, and
+ * the node implements "row IS [NOT] NULL" per the SQL standard.  This
+ * includes checking individual fields for NULLness when the row datum
+ * itself isn't NULL.
+ *
+ * NOTE: the combination of a rowtype input and argisrow==false does NOT
+ * correspond to the SQL notation "row IS [NOT] NULL"; instead, this case
+ * represents the SQL notation "row IS [NOT] DISTINCT FROM NULL".
+ * ----------------
+ */
+
+typedef enum NullTestType
+{
+	IS_NULL, IS_NOT_NULL
+} NullTestType;
+
+typedef struct NullTest
+{
+	Expr		xpr;
+	Expr	   *arg;			/* input expression */
+	NullTestType nulltesttype;	/* IS NULL, IS NOT NULL */
+	bool		argisrow;		/* T to perform field-by-field null checks */
+	int			location;		/* token location, or -1 if unknown */
+} NullTest;
+
+/*
+ * BooleanTest
+ *
+ * BooleanTest represents the operation of determining whether a boolean
+ * is TRUE, FALSE, or UNKNOWN (ie, NULL).  All six meaningful combinations
+ * are supported.  Note that a NULL input does *not* cause a NULL result.
+ * The appropriate test is performed and returned as a boolean Datum.
+ */
+
+typedef enum BoolTestType
+{
+	IS_TRUE, IS_NOT_TRUE, IS_FALSE, IS_NOT_FALSE, IS_UNKNOWN, IS_NOT_UNKNOWN
+} BoolTestType;
+
+typedef struct BooleanTest
+{
+	Expr		xpr;
+	Expr	   *arg;			/* input expression */
+	BoolTestType booltesttype;	/* test type */
+	int			location;		/* token location, or -1 if unknown */
+} BooleanTest;
+
+/*
+ * CoerceToDomain
+ *
+ * CoerceToDomain represents the operation of coercing a value to a domain
+ * type.  At runtime (and not before) the precise set of constraints to be
+ * checked will be determined.  If the value passes, it is returned as the
+ * result; if not, an error is raised.  Note that this is equivalent to
+ * RelabelType in the scenario where no constraints are applied.
+ */
+typedef struct CoerceToDomain
+{
+	Expr		xpr;
+	Expr	   *arg;			/* input expression */
+	Oid			resulttype;		/* domain type ID (result type) */
+	int32		resulttypmod;	/* output typmod (currently always -1) */
+	Oid			resultcollid;	/* OID of collation, or InvalidOid if none */
+	CoercionForm coercionformat;	/* how to display this node */
+	int			location;		/* token location, or -1 if unknown */
+} CoerceToDomain;
+
+/*
+ * Placeholder node for the value to be processed by a domain's check
+ * constraint.  This is effectively like a Param, but can be implemented more
+ * simply since we need only one replacement value at a time.
+ *
+ * Note: the typeId/typeMod/collation will be set from the domain's base type,
+ * not the domain itself.  This is because we shouldn't consider the value
+ * to be a member of the domain if we haven't yet checked its constraints.
+ */
+typedef struct CoerceToDomainValue
+{
+	Expr		xpr;
+	Oid			typeId;			/* type for substituted value */
+	int32		typeMod;		/* typemod for substituted value */
+	Oid			collation;		/* collation for the substituted value */
+	int			location;		/* token location, or -1 if unknown */
+} CoerceToDomainValue;
+
+/*
+ * Placeholder node for a DEFAULT marker in an INSERT or UPDATE command.
+ *
+ * This is not an executable expression: it must be replaced by the actual
+ * column default expression during rewriting.  But it is convenient to
+ * treat it as an expression node during parsing and rewriting.
+ */
+typedef struct SetToDefault
+{
+	Expr		xpr;
+	Oid			typeId;			/* type for substituted value */
+	int32		typeMod;		/* typemod for substituted value */
+	Oid			collation;		/* collation for the substituted value */
+	int			location;		/* token location, or -1 if unknown */
+} SetToDefault;
+
+/*
+ * Node representing [WHERE] CURRENT OF cursor_name
+ *
+ * CURRENT OF is a bit like a Var, in that it carries the rangetable index
+ * of the target relation being constrained; this aids placing the expression
+ * correctly during planning.  We can assume however that its "levelsup" is
+ * always zero, due to the syntactic constraints on where it can appear.
+ *
+ * The referenced cursor can be represented either as a hardwired string
+ * or as a reference to a run-time parameter of type REFCURSOR.  The latter
+ * case is for the convenience of plpgsql.
+ */
+typedef struct CurrentOfExpr
+{
+	Expr		xpr;
+	Index		cvarno;			/* RT index of target relation */
+	char	   *cursor_name;	/* name of referenced cursor, or NULL */
+	int			cursor_param;	/* refcursor parameter number, or 0 */
+} CurrentOfExpr;
+
+/*
+ * NextValueExpr - get next value from sequence
+ *
+ * This has the same effect as calling the nextval() function, but it does not
+ * check permissions on the sequence.  This is used for identity columns,
+ * where the sequence is an implicit dependency without its own permissions.
+ */
+typedef struct NextValueExpr
+{
+	Expr		xpr;
+	Oid			seqid;
+	Oid			typeId;
+} NextValueExpr;
+
+/*
+ * InferenceElem - an element of a unique index inference specification
+ *
+ * This mostly matches the structure of IndexElems, but having a dedicated
+ * primnode allows for a clean separation between the use of index parameters
+ * by utility commands, and this node.
+ */
+typedef struct InferenceElem
+{
+	Expr		xpr;
+	Node	   *expr;			/* expression to infer from, or NULL */
+	Oid			infercollid;	/* OID of collation, or InvalidOid */
+	Oid			inferopclass;	/* OID of att opclass, or InvalidOid */
+} InferenceElem;
+
+/*--------------------
+ * TargetEntry -
+ *	   a target entry (used in query target lists)
+ *
+ * Strictly speaking, a TargetEntry isn't an expression node (since it can't
+ * be evaluated by ExecEvalExpr).  But we treat it as one anyway, since in
+ * very many places it's convenient to process a whole query targetlist as a
+ * single expression tree.
+ *
+ * In a SELECT's targetlist, resno should always be equal to the item's
+ * ordinal position (counting from 1).  However, in an INSERT or UPDATE
+ * targetlist, resno represents the attribute number of the destination
+ * column for the item; so there may be missing or out-of-order resnos.
+ * It is even legal to have duplicated resnos; consider
+ *		UPDATE table SET arraycol[1] = ..., arraycol[2] = ..., ...
+ * In an INSERT, the rewriter and planner will normalize the tlist by
+ * reordering it into physical column order and filling in default values
+ * for any columns not assigned values by the original query.  In an UPDATE,
+ * after the rewriter merges multiple assignments for the same column, the
+ * planner extracts the target-column numbers into a separate "update_colnos"
+ * list, and then renumbers the tlist elements serially.  Thus, tlist resnos
+ * match ordinal position in all tlists seen by the executor; but it is wrong
+ * to assume that before planning has happened.
+ *
+ * resname is required to represent the correct column name in non-resjunk
+ * entries of top-level SELECT targetlists, since it will be used as the
+ * column title sent to the frontend.  In most other contexts it is only
+ * a debugging aid, and may be wrong or even NULL.  (In particular, it may
+ * be wrong in a tlist from a stored rule, if the referenced column has been
+ * renamed by ALTER TABLE since the rule was made.  Also, the planner tends
+ * to store NULL rather than look up a valid name for tlist entries in
+ * non-toplevel plan nodes.)  In resjunk entries, resname should be either
+ * a specific system-generated name (such as "ctid") or NULL; anything else
+ * risks confusing ExecGetJunkAttribute!
+ *
+ * ressortgroupref is used in the representation of ORDER BY, GROUP BY, and
+ * DISTINCT items.  Targetlist entries with ressortgroupref=0 are not
+ * sort/group items.  If ressortgroupref>0, then this item is an ORDER BY,
+ * GROUP BY, and/or DISTINCT target value.  No two entries in a targetlist
+ * may have the same nonzero ressortgroupref --- but there is no particular
+ * meaning to the nonzero values, except as tags.  (For example, one must
+ * not assume that lower ressortgroupref means a more significant sort key.)
+ * The order of the associated SortGroupClause lists determine the semantics.
+ *
+ * resorigtbl/resorigcol identify the source of the column, if it is a
+ * simple reference to a column of a base table (or view).  If it is not
+ * a simple reference, these fields are zeroes.
+ *
+ * If resjunk is true then the column is a working column (such as a sort key)
+ * that should be removed from the final output of the query.  Resjunk columns
+ * must have resnos that cannot duplicate any regular column's resno.  Also
+ * note that there are places that assume resjunk columns come after non-junk
+ * columns.
+ *--------------------
+ */
+typedef struct TargetEntry
+{
+	Expr		xpr;
+	Expr	   *expr;			/* expression to evaluate */
+	AttrNumber	resno;			/* attribute number (see notes above) */
+	char	   *resname;		/* name of the column (could be NULL) */
+	Index		ressortgroupref;	/* nonzero if referenced by a sort/group
+									 * clause */
+	Oid			resorigtbl;		/* OID of column's source table */
+	AttrNumber	resorigcol;		/* column's number in source table */
+	bool		resjunk;		/* set to true to eliminate the attribute from
+								 * final target list */
+} TargetEntry;
+
+
+/* ----------------------------------------------------------------
+ *					node types for join trees
+ *
+ * The leaves of a join tree structure are RangeTblRef nodes.  Above
+ * these, JoinExpr nodes can appear to denote a specific kind of join
+ * or qualified join.  Also, FromExpr nodes can appear to denote an
+ * ordinary cross-product join ("FROM foo, bar, baz WHERE ...").
+ * FromExpr is like a JoinExpr of jointype JOIN_INNER, except that it
+ * may have any number of child nodes, not just two.
+ *
+ * NOTE: the top level of a Query's jointree is always a FromExpr.
+ * Even if the jointree contains no rels, there will be a FromExpr.
+ *
+ * NOTE: the qualification expressions present in JoinExpr nodes are
+ * *in addition to* the query's main WHERE clause, which appears as the
+ * qual of the top-level FromExpr.  The reason for associating quals with
+ * specific nodes in the jointree is that the position of a qual is critical
+ * when outer joins are present.  (If we enforce a qual too soon or too late,
+ * that may cause the outer join to produce the wrong set of NULL-extended
+ * rows.)  If all joins are inner joins then all the qual positions are
+ * semantically interchangeable.
+ *
+ * NOTE: in the raw output of gram.y, a join tree contains RangeVar,
+ * RangeSubselect, and RangeFunction nodes, which are all replaced by
+ * RangeTblRef nodes during the parse analysis phase.  Also, the top-level
+ * FromExpr is added during parse analysis; the grammar regards FROM and
+ * WHERE as separate.
+ * ----------------------------------------------------------------
+ */
+
+/*
+ * RangeTblRef - reference to an entry in the query's rangetable
+ *
+ * We could use direct pointers to the RT entries and skip having these
+ * nodes, but multiple pointers to the same node in a querytree cause
+ * lots of headaches, so it seems better to store an index into the RT.
+ */
+typedef struct RangeTblRef
+{
+	NodeTag		type;
+	int			rtindex;
+} RangeTblRef;
+
+/*----------
+ * JoinExpr - for SQL JOIN expressions
+ *
+ * isNatural, usingClause, and quals are interdependent.  The user can write
+ * only one of NATURAL, USING(), or ON() (this is enforced by the grammar).
+ * If he writes NATURAL then parse analysis generates the equivalent USING()
+ * list, and from that fills in "quals" with the right equality comparisons.
+ * If he writes USING() then "quals" is filled with equality comparisons.
+ * If he writes ON() then only "quals" is set.  Note that NATURAL/USING
+ * are not equivalent to ON() since they also affect the output column list.
+ *
+ * alias is an Alias node representing the AS alias-clause attached to the
+ * join expression, or NULL if no clause.  NB: presence or absence of the
+ * alias has a critical impact on semantics, because a join with an alias
+ * restricts visibility of the tables/columns inside it.
+ *
+ * join_using_alias is an Alias node representing the join correlation
+ * name that SQL:2016 and later allow to be attached to JOIN/USING.
+ * Its column alias list includes only the common column names from USING,
+ * and it does not restrict visibility of the join's input tables.
+ *
+ * During parse analysis, an RTE is created for the Join, and its index
+ * is filled into rtindex.  This RTE is present mainly so that Vars can
+ * be created that refer to the outputs of the join.  The planner sometimes
+ * generates JoinExprs internally; these can have rtindex = 0 if there are
+ * no join alias variables referencing such joins.
+ *----------
+ */
+typedef struct JoinExpr
+{
+	NodeTag		type;
+	JoinType	jointype;		/* type of join */
+	bool		isNatural;		/* Natural join? Will need to shape table */
+	Node	   *larg;			/* left subtree */
+	Node	   *rarg;			/* right subtree */
+	List	   *usingClause;	/* USING clause, if any (list of String) */
+	Alias	   *join_using_alias;	/* alias attached to USING clause, if any */
+	Node	   *quals;			/* qualifiers on join, if any */
+	Alias	   *alias;			/* user-written alias clause, if any */
+	int			rtindex;		/* RT index assigned for join, or 0 */
+} JoinExpr;
+
+/*----------
+ * FromExpr - represents a FROM ... WHERE ... construct
+ *
+ * This is both more flexible than a JoinExpr (it can have any number of
+ * children, including zero) and less so --- we don't need to deal with
+ * aliases and so on.  The output column set is implicitly just the union
+ * of the outputs of the children.
+ *----------
+ */
+typedef struct FromExpr
+{
+	NodeTag		type;
+	List	   *fromlist;		/* List of join subtrees */
+	Node	   *quals;			/* qualifiers on join, if any */
+} FromExpr;
+
+/*----------
+ * OnConflictExpr - represents an ON CONFLICT DO ... expression
+ *
+ * The optimizer requires a list of inference elements, and optionally a WHERE
+ * clause to infer a unique index.  The unique index (or, occasionally,
+ * indexes) inferred are used to arbitrate whether or not the alternative ON
+ * CONFLICT path is taken.
+ *----------
+ */
+typedef struct OnConflictExpr
+{
+	NodeTag		type;
+	OnConflictAction action;	/* DO NOTHING or UPDATE? */
+
+	/* Arbiter */
+	List	   *arbiterElems;	/* unique index arbiter list (of
+								 * InferenceElem's) */
+	Node	   *arbiterWhere;	/* unique index arbiter WHERE clause */
+	Oid			constraint;		/* pg_constraint OID for arbiter */
+
+	/* ON CONFLICT UPDATE */
+	List	   *onConflictSet;	/* List of ON CONFLICT SET TargetEntrys */
+	Node	   *onConflictWhere;	/* qualifiers to restrict UPDATE to */
+	int			exclRelIndex;	/* RT index of 'excluded' relation */
+	List	   *exclRelTlist;	/* tlist of the EXCLUDED pseudo relation */
+} OnConflictExpr;
+
+#endif							/* PRIMNODES_H */