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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 */ |