/*------------------------------------------------------------------------- * * 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) 1996-2019, 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) * * Note: during parsing/planning, varnoold/varoattno are always just copies * of varno/varattno. At the tail 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.) In all these cases, varnoold/varoattno hold the * original values. The code doesn't really need varnoold/varoattno, but they * are very useful for debugging and interpreting completed plans, so we keep * them around. */ #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 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 varnoold; /* original value of varno, for debugging */ AttrNumber varoattno; /* original value of varattno */ 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. */ 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 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 container (e.g. 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". * * Note: the result datatype is the element type when fetching a single * element; but it is the array type when doing subarray fetch or either * type of store. * * 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; /* type of the container elements */ int32 reftypmod; /* typmod of the container (and elements too) */ Oid refcollid; /* OID of collation, 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_EXPLICIT /* explicit cast operation */ } CoercionContext; /* * CoercionForm - how to display a node that could have come from a cast * * 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 */ } 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. */ typedef struct ScalarArrayOpExpr { Expr xpr; Oid opno; /* PG_OPERATOR OID of the operator */ Oid opfuncid; /* PG_PROC OID of underlying function */ 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 or MULTIEXPR plan; 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 and MULTIEXPR 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 */ /* Copied from original SubLink, but placed at end for ABI stability */ int subLinkId; /* ID (1..n); 0 if not MULTIEXPR */ } SubPlan; /* * AlternativeSubPlan - expression node for a choice among SubPlans * * 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 * and others as . 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] = ..., ... * The two meanings come together in the executor, because the planner * transforms INSERT/UPDATE tlists into a normalized form with exactly * one entry for each column of the destination table. Before that's * happened, however, it is risky to assume that resno == position. * Generally get_tle_by_resno() should be used rather than list_nth() * to fetch tlist entries by resno, and only in SELECT should you assume * that resno is a unique identifier. * * 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. * * 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) */ 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 */