/*------------------------------------------------------------------------- * * 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) 1996-2002, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * * $Id: primnodes.h,v 1.72 2002/12/12 15:49:40 tgl Exp $ * *------------------------------------------------------------------------- */ #ifndef PRIMNODES_H #define PRIMNODES_H #include "access/attnum.h" #include "nodes/pg_list.h" /* FunctionCache is declared in utils/fcache.h */ typedef struct FunctionCache *FunctionCachePtr; /* ---------------------------------------------------------------- * node definitions * ---------------------------------------------------------------- */ /*-------------------- * Resdom (Result Domain) * * Notes: * ressortgroupref is the parse/plan-time representation of ORDER BY and * GROUP BY items. Targetlist entries with ressortgroupref=0 are not * sort/group items. If ressortgroupref>0, then this item is an ORDER BY or * GROUP BY 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 SortClause or GroupClause lists determine the semantics. * * reskey and reskeyop are the execution-time representation of sorting. * reskey must be zero in any non-sort-key item. The reskey of sort key * targetlist items for a sort plan node is 1,2,...,n for the n sort keys. * The reskeyop of each such targetlist item is the sort operator's OID. * reskeyop will be zero in non-sort-key items. * * Both reskey and reskeyop are typically zero during parse/plan stages. * The executor does not pay any attention to ressortgroupref. *-------------------- */ typedef struct Resdom { NodeTag type; AttrNumber resno; /* attribute number */ Oid restype; /* type of the value */ int32 restypmod; /* type-specific modifier of the value */ char *resname; /* name of the resdom (could be NULL) */ Index ressortgroupref; /* nonzero if referenced by a sort/group clause */ Index reskey; /* order of key in a sort (for those > 0) */ Oid reskeyop; /* sort operator's Oid */ bool resjunk; /* set to true to eliminate the attribute * from final target list */ } Resdom; /* * Alias - * specifies an alias for a range variable; the alias might also * specify renaming of columns within the table. */ typedef struct Alias { NodeTag type; char *aliasname; /* aliased rel name (never qualified) */ List *colnames; /* optional list of column aliases */ /* Note: colnames is a list of Value nodes (always strings) */ } Alias; typedef enum InhOption { INH_NO, /* Do NOT scan child tables */ INH_YES, /* DO scan child tables */ INH_DEFAULT /* Use current SQL_inheritance option */ } InhOption; /* * RangeVar - range variable, used in FROM clauses * * Also used to represent table names in utility statements; there, the alias * field is not used, and inhOpt shows 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 */ InhOption inhOpt; /* expand rel by inheritance? recursively * act on children? */ bool istemp; /* is this a temp relation/sequence? */ Alias *alias; /* table alias & optional column aliases */ } RangeVar; /* ---------------------------------------------------------------- * 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 or OUTER and * varattno becomes the index of the proper element of that subplan's target * list. But varnoold/varoattno continue to 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 65000 #define OUTER 65001 #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 (could also be INNER or * OUTER) */ AttrNumber varattno; /* attribute number of this var, or zero * for all */ Oid vartype; /* pg_type tuple OID for the type of this * var */ int32 vartypmod; /* pg_attribute typmod value */ 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 */ } Var; /* * Const */ typedef struct Const { Expr xpr; Oid consttype; /* PG_TYPE OID of the constant's datatype */ 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. */ } Const; /* ---------------- * Param * paramkind - specifies the kind of parameter. The possible values * for this field are specified in "params.h", and they are: * * PARAM_NAMED: The parameter has a name, i.e. something * like `$.salary' or `$.foobar'. * In this case field `paramname' must be a valid name. * * PARAM_NUM: The parameter has only a numeric identifier, * i.e. something like `$1', `$2' etc. * The number is contained in the `paramid' field. * * PARAM_EXEC: The parameter is an internal executor parameter. * It has a number contained in the `paramid' field. * ---------------- */ typedef struct Param { Expr xpr; int paramkind; /* kind of parameter. See above */ AttrNumber paramid; /* numeric ID for parameter ("$1") */ char *paramname; /* name for parameter ("$.foo") */ Oid paramtype; /* PG_TYPE OID of parameter's datatype */ } Param; /* * Aggref */ typedef struct Aggref { Expr xpr; Oid aggfnoid; /* pg_proc Oid of the aggregate */ Oid aggtype; /* type Oid of result of the aggregate */ Expr *target; /* expression we are aggregating on */ bool aggstar; /* TRUE if argument was really '*' */ bool aggdistinct; /* TRUE if it's agg(DISTINCT ...) */ /* XXX this should move to AggrefExprState: */ int aggno; /* workspace for executor (see nodeAgg.c) */ } Aggref; /* ---------------- * ArrayRef: describes an array subscripting operation * * An ArrayRef can describe fetching a single element from an array, * fetching a subarray (array slice), storing a single element into * an array, or storing a slice. The "store" cases work with an * initial array value and a source value that is inserted into the * appropriate part of the array; the result of the operation is an * entire new modified array value. * * If reflowerindexpr = NIL, then we are fetching or storing a single array * element at the subscripts given by refupperindexpr. Otherwise we are * fetching or storing an array slice, that is a rectangular subarray * with lower and upper bounds given by the index expressions. * reflowerindexpr must be the same length as refupperindexpr when it * is not NIL. * * Note: array types can be fixed-length (refattrlength > 0), but only * when the element type is itself fixed-length. Otherwise they are * varlena structures and have refattrlength = -1. In any case, * an array type is never pass-by-value. * * Note: refrestype is NOT the element type, but the array type, * when doing subarray fetch or either type of store. It might be a good * idea to include a refelemtype field as well. * ---------------- */ typedef struct ArrayRef { Expr xpr; Oid refrestype; /* type of the result of the ArrayRef * operation */ int refattrlength; /* typlen of array type */ int refelemlength; /* typlen of the array element type */ bool refelembyval; /* is the element type pass-by-value? */ char refelemalign; /* typalign of the element type */ List *refupperindexpr;/* expressions that evaluate to upper * array indexes */ List *reflowerindexpr;/* expressions that evaluate to lower * array indexes */ Expr *refexpr; /* the expression that evaluates to an * array value */ Expr *refassgnexpr; /* expression for the source value, or * NULL if fetch */ } ArrayRef; /* * 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 - information showing how to display a function-call node */ 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_DONTCARE /* special case for pathkeys */ } 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 */ CoercionForm funcformat; /* how to display this function call */ List *args; /* arguments to the function */ FunctionCachePtr func_fcache; /* XXX runtime state, or NULL */ } FuncExpr; /* * 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 is typically 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 */ List *args; /* arguments to the operator (1 or 2) */ FunctionCachePtr op_fcache; /* XXX runtime state, else NULL */ } 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; /* * 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, the executor can * handle any number of arguments. The parser treats AND and OR as binary * and so it only produces two-element lists, but the optimizer will flatten * trees of AND and OR nodes to produce longer lists when possible. */ typedef enum BoolExprType { AND_EXPR, OR_EXPR, NOT_EXPR } BoolExprType; typedef struct BoolExpr { Expr xpr; BoolExprType boolop; List *args; /* arguments to this expression */ } 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 ...) * MULTIEXPR_SUBLINK (lefthand) op (SELECT ...) * EXPR_SUBLINK (SELECT with single targetlist item ...) * For ALL, ANY, and MULTIEXPR, the lefthand is a list of expressions of the * same length as the subselect's targetlist. MULTIEXPR 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). Note that both * MULTIEXPR and EXPR require the subselect to deliver only one row. * ALL, ANY, and MULTIEXPR require the combining operators to deliver boolean * results. These are reduced to one result per row using OR or AND semantics * depending on the "useor" flag. ALL and ANY combine the per-row results * using AND and OR semantics respectively. * * SubLink is classed as an Expr node, but it is not actually executable; * it must be replaced in the expression tree by a SubPlanExpr node during * planning. * * NOTE: lefthand and oper have varying meanings depending on where you look * in the parse/plan pipeline: * 1. gram.y delivers a list of the (untransformed) lefthand expressions in * lefthand, and sets oper to a single A_Expr (not a list!) containing * the string name of the operator, but no arguments. * 2. The parser's expression transformation transforms lefthand normally, * and replaces oper with a list of OpExpr nodes, one per lefthand * expression. These nodes represent the parser's resolution of exactly * which operator to apply to each pair of lefthand and targetlist * expressions. However, we have not constructed complete Expr trees for * these operations yet: the args fields of the OpExpr nodes are NIL. * This is the representation seen in saved rules and in the rewriter. * 3. Finally, the planner converts the oper list to a list of normal OpExpr * nodes representing the application of the operator(s) to the lefthand * expressions and values from the inner targetlist. The inner * targetlist items are represented by placeholder Param nodes. * The lefthand field is set to NIL, since its expressions are now in * the Expr list. This representation is passed to the executor. * * Planner routines that might see either representation 2 or 3 can tell * the difference by checking whether lefthand is NIL or not. Also, * representation 2 appears in a "bare" SubLink, while representation 3 is * found in SubLinks that are children of SubPlanExpr nodes. * * In EXISTS and EXPR SubLinks, both lefthand and oper are unused and are * always NIL. useor is not significant either for these sublink types. * ---------------- */ typedef enum SubLinkType { EXISTS_SUBLINK, ALL_SUBLINK, ANY_SUBLINK, MULTIEXPR_SUBLINK, EXPR_SUBLINK } SubLinkType; typedef struct SubLink { Expr xpr; SubLinkType subLinkType; /* EXISTS, ALL, ANY, MULTIEXPR, EXPR */ bool useor; /* TRUE to combine column results with * "OR" not "AND" */ List *lefthand; /* list of outer-query expressions on the * left */ List *oper; /* list of OpExpr nodes for combining * operators, or final list of executable * expressions */ Node *subselect; /* subselect as Query* or parsetree */ } SubLink; /* * SubPlanExpr - executable expression node for a subplan (sub-SELECT) * * The planner replaces SubLink nodes in expression trees with SubPlanExpr * nodes after it has finished planning the subquery. See notes above. */ typedef struct SubPlanExpr { Expr xpr; Oid typeOid; /* PG_TYPE OID of the expression result */ struct Plan *plan; /* subselect plan itself */ int plan_id; /* dummy thing because of we haven't equal * funcs for plan nodes... actually, we * could put *plan itself somewhere else * (TopPlan node ?)... */ List *rtable; /* range table for subselect */ /* setParam and parParam are lists of integers (param IDs) */ List *setParam; /* non-correlated EXPR & EXISTS subqueries * have to set some Params for paren Plan */ List *parParam; /* indices of input Params from parent plan */ List *args; /* exprs to pass as parParam values */ SubLink *sublink; /* SubLink node from parser; holds info * about what to do with subselect's * results */ struct SubPlanState *pstate; /* XXX TEMPORARY HACK */ } SubPlanExpr; /* ---------------- * FieldSelect * * FieldSelect represents the operation of extracting one field from a tuple * value. At runtime, the input expression is expected to yield a Datum * that contains a pointer-to-TupleTableSlot. 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) */ } FieldSelect; /* ---------------- * 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) */ CoercionForm relabelformat; /* how to display this node */ } RelabelType; /* * CaseExpr - a CASE expression */ typedef struct CaseExpr { Expr xpr; Oid casetype; /* type of expression result */ Expr *arg; /* implicit equality comparison argument */ List *args; /* the arguments (list of WHEN clauses) */ Expr *defresult; /* the default result (ELSE clause) */ } CaseExpr; /* * CaseWhen - an argument to a CASE expression */ typedef struct CaseWhen { Expr xpr; Expr *expr; /* condition expression */ Expr *result; /* substitution result */ } CaseWhen; /* ---------------- * NullTest * * NullTest represents the operation of testing a value for NULLness. * Currently, we only support scalar input values, but eventually a * row-constructor input should be supported. * The appropriate test is performed and returned as a boolean Datum. * ---------------- */ 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 */ } 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 */ } BooleanTest; /* * ConstraintTest * * ConstraintTest represents the operation of testing a value to see whether * it meets a constraint. If so, the input value is returned as the result; * if not, an error is raised. */ typedef enum ConstraintTestType { CONSTR_TEST_NOTNULL, CONSTR_TEST_CHECK } ConstraintTestType; typedef struct ConstraintTest { Expr xpr; Expr *arg; /* input expression */ ConstraintTestType testtype; /* test type */ char *name; /* name of constraint (for error msgs) */ char *domname; /* name of domain (for error messages) */ Expr *check_expr; /* for CHECK test, a boolean expression */ } ConstraintTest; /* * Placeholder node for the value to be processed by a domains * check constraint. This is effectively like a Param; could we use * a Param node instead? */ typedef struct ConstraintTestValue { Expr xpr; Oid typeId; int32 typeMod; } ConstraintTestValue; /* * 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. * * The separation between TargetEntry and Resdom is historical. One of these * days, Resdom should probably get folded into TargetEntry. */ typedef struct TargetEntry { Expr xpr; Resdom *resdom; /* descriptor for targetlist item */ Expr *expr; /* expression to evaluate */ } 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. Also, there is an * implementation-defined difference: the planner is allowed to join the * children of a FromExpr using whatever join order seems good to it. * At present, JoinExpr nodes are always joined in exactly the order * implied by the jointree structure (except the planner may choose to * swap inner and outer members of a join pair). * * 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, using, 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. *---------- */ 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 *using; /* 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 */ } 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; #endif /* PRIMNODES_H */