/*------------------------------------------------------------------------- * * setrefs.c * Post-processing of a completed plan tree: fix references to subplan * vars, and compute regproc values for operators * * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * * * IDENTIFICATION * $PostgreSQL: pgsql/src/backend/optimizer/plan/setrefs.c,v 1.136 2007/06/11 01:16:23 tgl Exp $ * *------------------------------------------------------------------------- */ #include "postgres.h" #include "nodes/makefuncs.h" #include "optimizer/clauses.h" #include "optimizer/planmain.h" #include "optimizer/tlist.h" #include "parser/parse_expr.h" #include "parser/parsetree.h" #include "utils/lsyscache.h" typedef struct { Index varno; /* RT index of Var */ AttrNumber varattno; /* attr number of Var */ AttrNumber resno; /* TLE position of Var */ } tlist_vinfo; typedef struct { List *tlist; /* underlying target list */ int num_vars; /* number of plain Var tlist entries */ bool has_non_vars; /* are there non-plain-Var entries? */ /* array of num_vars entries: */ tlist_vinfo vars[1]; /* VARIABLE LENGTH ARRAY */ } indexed_tlist; /* VARIABLE LENGTH STRUCT */ typedef struct { int rtoffset; } fix_scan_expr_context; typedef struct { indexed_tlist *outer_itlist; indexed_tlist *inner_itlist; Index acceptable_rel; int rtoffset; } fix_join_expr_context; typedef struct { indexed_tlist *subplan_itlist; int rtoffset; } fix_upper_expr_context; #define fix_scan_list(lst, rtoffset) \ ((List *) fix_scan_expr((Node *) (lst), rtoffset)) static Plan *set_plan_refs(PlannerGlobal *glob, Plan *plan, int rtoffset); static Plan *set_subqueryscan_references(PlannerGlobal *glob, SubqueryScan *plan, int rtoffset); static bool trivial_subqueryscan(SubqueryScan *plan); static Node *fix_scan_expr(Node *node, int rtoffset); static Node *fix_scan_expr_mutator(Node *node, fix_scan_expr_context *context); static void set_join_references(Join *join, int rtoffset); static void set_inner_join_references(Plan *inner_plan, indexed_tlist *outer_itlist); static void set_upper_references(Plan *plan, int rtoffset); static void set_dummy_tlist_references(Plan *plan, int rtoffset); static indexed_tlist *build_tlist_index(List *tlist); static Var *search_indexed_tlist_for_var(Var *var, indexed_tlist *itlist, Index newvarno, int rtoffset); static Var *search_indexed_tlist_for_non_var(Node *node, indexed_tlist *itlist, Index newvarno); static List *fix_join_expr(List *clauses, indexed_tlist *outer_itlist, indexed_tlist *inner_itlist, Index acceptable_rel, int rtoffset); static Node *fix_join_expr_mutator(Node *node, fix_join_expr_context *context); static Node *fix_upper_expr(Node *node, indexed_tlist *subplan_itlist, int rtoffset); static Node *fix_upper_expr_mutator(Node *node, fix_upper_expr_context *context); static bool fix_opfuncids_walker(Node *node, void *context); /***************************************************************************** * * SUBPLAN REFERENCES * *****************************************************************************/ /* * set_plan_references * * This is the final processing pass of the planner/optimizer. The plan * tree is complete; we just have to adjust some representational details * for the convenience of the executor: * * 1. We flatten the various subquery rangetables into a single list, and * zero out RangeTblEntry fields that are not useful to the executor. * * 2. We adjust Vars in scan nodes to be consistent with the flat rangetable. * * 3. We adjust Vars in upper plan nodes to refer to the outputs of their * subplans. * * 4. We compute regproc OIDs for operators (ie, we look up the function * that implements each op). * * We also perform one final optimization step, which is to delete * SubqueryScan plan nodes that aren't doing anything useful (ie, have * no qual and a no-op targetlist). The reason for doing this last is that * it can't readily be done before set_plan_references, because it would * break set_upper_references: the Vars in the subquery's top tlist * wouldn't match up with the Vars in the outer plan tree. The SubqueryScan * serves a necessary function as a buffer between outer query and subquery * variable numbering ... but after we've flattened the rangetable this is * no longer a problem, since there's only one rtindex namespace. * * set_plan_references recursively traverses the whole plan tree. * * Inputs: * glob: global data for planner run * plan: the topmost node of the plan * rtable: the rangetable for the current subquery * * The return value is normally the same Plan node passed in, but can be * different when the passed-in Plan is a SubqueryScan we decide isn't needed. * * The flattened rangetable entries are appended to glob->finalrtable. * * Notice that we modify Plan nodes in-place, but use expression_tree_mutator * to process targetlist and qual expressions. We can assume that the Plan * nodes were just built by the planner and are not multiply referenced, but * it's not so safe to assume that for expression tree nodes. */ Plan * set_plan_references(PlannerGlobal *glob, Plan *plan, List *rtable) { int rtoffset = list_length(glob->finalrtable); ListCell *lc; /* * In the flat rangetable, we zero out substructure pointers that are * not needed by the executor; this reduces the storage space and * copying cost for cached plans. We keep only the alias and eref * Alias fields, which are needed by EXPLAIN. */ foreach(lc, rtable) { RangeTblEntry *rte = (RangeTblEntry *) lfirst(lc); RangeTblEntry *newrte; /* flat copy to duplicate all the scalar fields */ newrte = (RangeTblEntry *) palloc(sizeof(RangeTblEntry)); memcpy(newrte, rte, sizeof(RangeTblEntry)); /* zap unneeded sub-structure */ newrte->subquery = NULL; newrte->funcexpr = NULL; newrte->funccoltypes = NIL; newrte->funccoltypmods = NIL; newrte->values_lists = NIL; newrte->joinaliasvars = NIL; glob->finalrtable = lappend(glob->finalrtable, newrte); } /* Now fix the Plan tree */ return set_plan_refs(glob, plan, rtoffset); } /* * set_plan_refs: recurse through the Plan nodes of a single subquery level */ static Plan * set_plan_refs(PlannerGlobal *glob, Plan *plan, int rtoffset) { ListCell *l; if (plan == NULL) return NULL; /* * Plan-type-specific fixes */ switch (nodeTag(plan)) { case T_SeqScan: { SeqScan *splan = (SeqScan *) plan; splan->scanrelid += rtoffset; splan->plan.targetlist = fix_scan_list(splan->plan.targetlist, rtoffset); splan->plan.qual = fix_scan_list(splan->plan.qual, rtoffset); } break; case T_IndexScan: { IndexScan *splan = (IndexScan *) plan; splan->scan.scanrelid += rtoffset; splan->scan.plan.targetlist = fix_scan_list(splan->scan.plan.targetlist, rtoffset); splan->scan.plan.qual = fix_scan_list(splan->scan.plan.qual, rtoffset); splan->indexqual = fix_scan_list(splan->indexqual, rtoffset); splan->indexqualorig = fix_scan_list(splan->indexqualorig, rtoffset); } break; case T_BitmapIndexScan: { BitmapIndexScan *splan = (BitmapIndexScan *) plan; splan->scan.scanrelid += rtoffset; /* no need to fix targetlist and qual */ Assert(splan->scan.plan.targetlist == NIL); Assert(splan->scan.plan.qual == NIL); splan->indexqual = fix_scan_list(splan->indexqual, rtoffset); splan->indexqualorig = fix_scan_list(splan->indexqualorig, rtoffset); } break; case T_BitmapHeapScan: { BitmapHeapScan *splan = (BitmapHeapScan *) plan; splan->scan.scanrelid += rtoffset; splan->scan.plan.targetlist = fix_scan_list(splan->scan.plan.targetlist, rtoffset); splan->scan.plan.qual = fix_scan_list(splan->scan.plan.qual, rtoffset); splan->bitmapqualorig = fix_scan_list(splan->bitmapqualorig, rtoffset); } break; case T_TidScan: { TidScan *splan = (TidScan *) plan; splan->scan.scanrelid += rtoffset; splan->scan.plan.targetlist = fix_scan_list(splan->scan.plan.targetlist, rtoffset); splan->scan.plan.qual = fix_scan_list(splan->scan.plan.qual, rtoffset); splan->tidquals = fix_scan_list(splan->tidquals, rtoffset); } break; case T_SubqueryScan: /* Needs special treatment, see comments below */ return set_subqueryscan_references(glob, (SubqueryScan *) plan, rtoffset); case T_FunctionScan: { FunctionScan *splan = (FunctionScan *) plan; splan->scan.scanrelid += rtoffset; splan->scan.plan.targetlist = fix_scan_list(splan->scan.plan.targetlist, rtoffset); splan->scan.plan.qual = fix_scan_list(splan->scan.plan.qual, rtoffset); splan->funcexpr = fix_scan_expr(splan->funcexpr, rtoffset); } break; case T_ValuesScan: { ValuesScan *splan = (ValuesScan *) plan; splan->scan.scanrelid += rtoffset; splan->scan.plan.targetlist = fix_scan_list(splan->scan.plan.targetlist, rtoffset); splan->scan.plan.qual = fix_scan_list(splan->scan.plan.qual, rtoffset); splan->values_lists = fix_scan_list(splan->values_lists, rtoffset); } break; case T_NestLoop: case T_MergeJoin: case T_HashJoin: set_join_references((Join *) plan, rtoffset); break; case T_Hash: case T_Material: case T_Sort: case T_Unique: case T_SetOp: /* * These plan types don't actually bother to evaluate their * targetlists, because they just return their unmodified input * tuples. Even though the targetlist won't be used by the * executor, we fix it up for possible use by EXPLAIN (not to * mention ease of debugging --- wrong varnos are very confusing). */ set_dummy_tlist_references(plan, rtoffset); /* * Since these plan types don't check quals either, we should not * find any qual expression attached to them. */ Assert(plan->qual == NIL); break; case T_Limit: { Limit *splan = (Limit *) plan; /* * Like the plan types above, Limit doesn't evaluate its tlist * or quals. It does have live expressions for limit/offset, * however; and those cannot contain subplan variable refs, * so fix_scan_expr works for them. */ set_dummy_tlist_references(plan, rtoffset); Assert(splan->plan.qual == NIL); splan->limitOffset = fix_scan_expr(splan->limitOffset, rtoffset); splan->limitCount = fix_scan_expr(splan->limitCount, rtoffset); } break; case T_Agg: case T_Group: set_upper_references(plan, rtoffset); break; case T_Result: { Result *splan = (Result *) plan; /* * Result may or may not have a subplan; if not, it's more * like a scan node than an upper node. */ if (splan->plan.lefttree != NULL) set_upper_references(plan, rtoffset); else { splan->plan.targetlist = fix_scan_list(splan->plan.targetlist, rtoffset); splan->plan.qual = fix_scan_list(splan->plan.qual, rtoffset); } /* resconstantqual can't contain any subplan variable refs */ splan->resconstantqual = fix_scan_expr(splan->resconstantqual, rtoffset); } break; case T_Append: { Append *splan = (Append *) plan; /* * Append, like Sort et al, doesn't actually evaluate its * targetlist or check quals. */ set_dummy_tlist_references(plan, rtoffset); Assert(splan->plan.qual == NIL); foreach(l, splan->appendplans) { lfirst(l) = set_plan_refs(glob, (Plan *) lfirst(l), rtoffset); } } break; case T_BitmapAnd: { BitmapAnd *splan = (BitmapAnd *) plan; /* BitmapAnd works like Append, but has no tlist */ Assert(splan->plan.targetlist == NIL); Assert(splan->plan.qual == NIL); foreach(l, splan->bitmapplans) { lfirst(l) = set_plan_refs(glob, (Plan *) lfirst(l), rtoffset); } } break; case T_BitmapOr: { BitmapOr *splan = (BitmapOr *) plan; /* BitmapOr works like Append, but has no tlist */ Assert(splan->plan.targetlist == NIL); Assert(splan->plan.qual == NIL); foreach(l, splan->bitmapplans) { lfirst(l) = set_plan_refs(glob, (Plan *) lfirst(l), rtoffset); } } break; default: elog(ERROR, "unrecognized node type: %d", (int) nodeTag(plan)); break; } /* * Now recurse into child plans, if any * * NOTE: it is essential that we recurse into child plans AFTER we set * subplan references in this plan's tlist and quals. If we did the * reference-adjustments bottom-up, then we would fail to match this * plan's var nodes against the already-modified nodes of the children. */ plan->lefttree = set_plan_refs(glob, plan->lefttree, rtoffset); plan->righttree = set_plan_refs(glob, plan->righttree, rtoffset); return plan; } /* * set_subqueryscan_references * Do set_plan_references processing on a SubqueryScan * * We try to strip out the SubqueryScan entirely; if we can't, we have * to do the normal processing on it. */ static Plan * set_subqueryscan_references(PlannerGlobal *glob, SubqueryScan *plan, int rtoffset) { Plan *result; /* First, recursively process the subplan */ plan->subplan = set_plan_references(glob, plan->subplan, plan->subrtable); /* subrtable is no longer needed in the plan tree */ plan->subrtable = NIL; if (trivial_subqueryscan(plan)) { /* * We can omit the SubqueryScan node and just pull up the subplan. */ ListCell *lp, *lc; result = plan->subplan; /* We have to be sure we don't lose any initplans */ result->initPlan = list_concat(plan->scan.plan.initPlan, result->initPlan); /* * We also have to transfer the SubqueryScan's result-column names * into the subplan, else columns sent to client will be improperly * labeled if this is the topmost plan level. Copy the "source * column" information too. */ forboth(lp, plan->scan.plan.targetlist, lc, result->targetlist) { TargetEntry *ptle = (TargetEntry *) lfirst(lp); TargetEntry *ctle = (TargetEntry *) lfirst(lc); ctle->resname = ptle->resname; ctle->resorigtbl = ptle->resorigtbl; ctle->resorigcol = ptle->resorigcol; } } else { /* * Keep the SubqueryScan node. We have to do the processing that * set_plan_references would otherwise have done on it. Notice we do * not do set_upper_references() here, because a SubqueryScan will * always have been created with correct references to its subplan's * outputs to begin with. */ plan->scan.scanrelid += rtoffset; plan->scan.plan.targetlist = fix_scan_list(plan->scan.plan.targetlist, rtoffset); plan->scan.plan.qual = fix_scan_list(plan->scan.plan.qual, rtoffset); result = (Plan *) plan; } return result; } /* * trivial_subqueryscan * Detect whether a SubqueryScan can be deleted from the plan tree. * * We can delete it if it has no qual to check and the targetlist just * regurgitates the output of the child plan. */ static bool trivial_subqueryscan(SubqueryScan *plan) { int attrno; ListCell *lp, *lc; if (plan->scan.plan.qual != NIL) return false; if (list_length(plan->scan.plan.targetlist) != list_length(plan->subplan->targetlist)) return false; /* tlists not same length */ attrno = 1; forboth(lp, plan->scan.plan.targetlist, lc, plan->subplan->targetlist) { TargetEntry *ptle = (TargetEntry *) lfirst(lp); TargetEntry *ctle = (TargetEntry *) lfirst(lc); if (ptle->resjunk != ctle->resjunk) return false; /* tlist doesn't match junk status */ /* * We accept either a Var referencing the corresponding element of the * subplan tlist, or a Const equaling the subplan element. See * generate_setop_tlist() for motivation. */ if (ptle->expr && IsA(ptle->expr, Var)) { Var *var = (Var *) ptle->expr; Assert(var->varno == plan->scan.scanrelid); Assert(var->varlevelsup == 0); if (var->varattno != attrno) return false; /* out of order */ } else if (ptle->expr && IsA(ptle->expr, Const)) { if (!equal(ptle->expr, ctle->expr)) return false; } else return false; attrno++; } return true; } /* * copyVar * Copy a Var node. * * fix_scan_expr and friends do this enough times that it's worth having * a bespoke routine instead of using the generic copyObject() function. */ static inline Var * copyVar(Var *var) { Var *newvar = (Var *) palloc(sizeof(Var)); *newvar = *var; return newvar; } /* * fix_scan_expr * Do set_plan_references processing on a scan-level expression * * This consists of incrementing all Vars' varnos by rtoffset and * looking up operator opcode info for OpExpr and related nodes. */ static Node * fix_scan_expr(Node *node, int rtoffset) { fix_scan_expr_context context; context.rtoffset = rtoffset; return fix_scan_expr_mutator(node, &context); } static Node * fix_scan_expr_mutator(Node *node, fix_scan_expr_context *context) { if (node == NULL) return NULL; if (IsA(node, Var)) { Var *var = copyVar((Var *) node); Assert(var->varlevelsup == 0); /* * We should not see any Vars marked INNER, but in a nestloop inner * scan there could be OUTER Vars. Leave them alone. */ Assert(var->varno != INNER); if (var->varno > 0 && var->varno != OUTER) var->varno += context->rtoffset; if (var->varnoold > 0) var->varnoold += context->rtoffset; return (Node *) var; } if (IsA(node, CurrentOfExpr)) { CurrentOfExpr *cexpr = (CurrentOfExpr *) copyObject(node); Assert(cexpr->cvarno != INNER); Assert(cexpr->cvarno != OUTER); cexpr->cvarno += context->rtoffset; return (Node *) cexpr; } /* * Since we update opcode info in-place, this part could possibly * scribble on the planner's input data structures, but it's OK. */ if (IsA(node, OpExpr)) set_opfuncid((OpExpr *) node); else if (IsA(node, DistinctExpr)) set_opfuncid((OpExpr *) node); /* rely on struct equivalence */ else if (IsA(node, NullIfExpr)) set_opfuncid((OpExpr *) node); /* rely on struct equivalence */ else if (IsA(node, ScalarArrayOpExpr)) set_sa_opfuncid((ScalarArrayOpExpr *) node); return expression_tree_mutator(node, fix_scan_expr_mutator, (void *) context); } /* * set_join_references * Modify the target list and quals of a join node to reference its * subplans, by setting the varnos to OUTER or INNER and setting attno * values to the result domain number of either the corresponding outer * or inner join tuple item. Also perform opcode lookup for these * expressions. * * In the case of a nestloop with inner indexscan, we will also need to * apply the same transformation to any outer vars appearing in the * quals of the child indexscan. set_inner_join_references does that. */ static void set_join_references(Join *join, int rtoffset) { Plan *outer_plan = join->plan.lefttree; Plan *inner_plan = join->plan.righttree; indexed_tlist *outer_itlist; indexed_tlist *inner_itlist; outer_itlist = build_tlist_index(outer_plan->targetlist); inner_itlist = build_tlist_index(inner_plan->targetlist); /* All join plans have tlist, qual, and joinqual */ join->plan.targetlist = fix_join_expr(join->plan.targetlist, outer_itlist, inner_itlist, (Index) 0, rtoffset); join->plan.qual = fix_join_expr(join->plan.qual, outer_itlist, inner_itlist, (Index) 0, rtoffset); join->joinqual = fix_join_expr(join->joinqual, outer_itlist, inner_itlist, (Index) 0, rtoffset); /* Now do join-type-specific stuff */ if (IsA(join, NestLoop)) { /* This processing is split out to handle possible recursion */ set_inner_join_references(inner_plan, outer_itlist); } else if (IsA(join, MergeJoin)) { MergeJoin *mj = (MergeJoin *) join; mj->mergeclauses = fix_join_expr(mj->mergeclauses, outer_itlist, inner_itlist, (Index) 0, rtoffset); } else if (IsA(join, HashJoin)) { HashJoin *hj = (HashJoin *) join; hj->hashclauses = fix_join_expr(hj->hashclauses, outer_itlist, inner_itlist, (Index) 0, rtoffset); } pfree(outer_itlist); pfree(inner_itlist); } /* * set_inner_join_references * Handle join references appearing in an inner indexscan's quals * * To handle bitmap-scan plan trees, we have to be able to recurse down * to the bottom BitmapIndexScan nodes; likewise, appendrel indexscans * require recursing through Append nodes. This is split out as a separate * function so that it can recurse. * * Note we do *not* apply any rtoffset for non-join Vars; this is because * the quals will be processed again by fix_scan_expr when the set_plan_refs * recursion reaches the inner indexscan, and so we'd have done it twice. */ static void set_inner_join_references(Plan *inner_plan, indexed_tlist *outer_itlist) { if (IsA(inner_plan, IndexScan)) { /* * An index is being used to reduce the number of tuples scanned in * the inner relation. If there are join clauses being used with the * index, we must update their outer-rel var nodes to refer to the * outer side of the join. */ IndexScan *innerscan = (IndexScan *) inner_plan; List *indexqualorig = innerscan->indexqualorig; /* No work needed if indexqual refers only to its own rel... */ if (NumRelids((Node *) indexqualorig) > 1) { Index innerrel = innerscan->scan.scanrelid; /* only refs to outer vars get changed in the inner qual */ innerscan->indexqualorig = fix_join_expr(indexqualorig, outer_itlist, NULL, innerrel, 0); innerscan->indexqual = fix_join_expr(innerscan->indexqual, outer_itlist, NULL, innerrel, 0); /* * We must fix the inner qpqual too, if it has join clauses (this * could happen if special operators are involved: some indexquals * may get rechecked as qpquals). */ if (NumRelids((Node *) inner_plan->qual) > 1) inner_plan->qual = fix_join_expr(inner_plan->qual, outer_itlist, NULL, innerrel, 0); } } else if (IsA(inner_plan, BitmapIndexScan)) { /* * Same, but index is being used within a bitmap plan. */ BitmapIndexScan *innerscan = (BitmapIndexScan *) inner_plan; List *indexqualorig = innerscan->indexqualorig; /* No work needed if indexqual refers only to its own rel... */ if (NumRelids((Node *) indexqualorig) > 1) { Index innerrel = innerscan->scan.scanrelid; /* only refs to outer vars get changed in the inner qual */ innerscan->indexqualorig = fix_join_expr(indexqualorig, outer_itlist, NULL, innerrel, 0); innerscan->indexqual = fix_join_expr(innerscan->indexqual, outer_itlist, NULL, innerrel, 0); /* no need to fix inner qpqual */ Assert(inner_plan->qual == NIL); } } else if (IsA(inner_plan, BitmapHeapScan)) { /* * The inner side is a bitmap scan plan. Fix the top node, and * recurse to get the lower nodes. * * Note: create_bitmap_scan_plan removes clauses from bitmapqualorig * if they are duplicated in qpqual, so must test these independently. */ BitmapHeapScan *innerscan = (BitmapHeapScan *) inner_plan; Index innerrel = innerscan->scan.scanrelid; List *bitmapqualorig = innerscan->bitmapqualorig; /* only refs to outer vars get changed in the inner qual */ if (NumRelids((Node *) bitmapqualorig) > 1) innerscan->bitmapqualorig = fix_join_expr(bitmapqualorig, outer_itlist, NULL, innerrel, 0); /* * We must fix the inner qpqual too, if it has join clauses (this * could happen if special operators are involved: some indexquals may * get rechecked as qpquals). */ if (NumRelids((Node *) inner_plan->qual) > 1) inner_plan->qual = fix_join_expr(inner_plan->qual, outer_itlist, NULL, innerrel, 0); /* Now recurse */ set_inner_join_references(inner_plan->lefttree, outer_itlist); } else if (IsA(inner_plan, BitmapAnd)) { /* All we need do here is recurse */ BitmapAnd *innerscan = (BitmapAnd *) inner_plan; ListCell *l; foreach(l, innerscan->bitmapplans) { set_inner_join_references((Plan *) lfirst(l), outer_itlist); } } else if (IsA(inner_plan, BitmapOr)) { /* All we need do here is recurse */ BitmapOr *innerscan = (BitmapOr *) inner_plan; ListCell *l; foreach(l, innerscan->bitmapplans) { set_inner_join_references((Plan *) lfirst(l), outer_itlist); } } else if (IsA(inner_plan, TidScan)) { TidScan *innerscan = (TidScan *) inner_plan; Index innerrel = innerscan->scan.scanrelid; innerscan->tidquals = fix_join_expr(innerscan->tidquals, outer_itlist, NULL, innerrel, 0); } else if (IsA(inner_plan, Append)) { /* * The inner side is an append plan. Recurse to see if it contains * indexscans that need to be fixed. */ Append *appendplan = (Append *) inner_plan; ListCell *l; foreach(l, appendplan->appendplans) { set_inner_join_references((Plan *) lfirst(l), outer_itlist); } } else if (IsA(inner_plan, Result)) { /* Recurse through a gating Result node (similar to Append case) */ Result *result = (Result *) inner_plan; if (result->plan.lefttree) set_inner_join_references(result->plan.lefttree, outer_itlist); } } /* * set_upper_references * Update the targetlist and quals of an upper-level plan node * to refer to the tuples returned by its lefttree subplan. * Also perform opcode lookup for these expressions. * * This is used for single-input plan types like Agg, Group, Result. * * In most cases, we have to match up individual Vars in the tlist and * qual expressions with elements of the subplan's tlist (which was * generated by flatten_tlist() from these selfsame expressions, so it * should have all the required variables). There is an important exception, * however: GROUP BY and ORDER BY expressions will have been pushed into the * subplan tlist unflattened. If these values are also needed in the output * then we want to reference the subplan tlist element rather than recomputing * the expression. */ static void set_upper_references(Plan *plan, int rtoffset) { Plan *subplan = plan->lefttree; indexed_tlist *subplan_itlist; List *output_targetlist; ListCell *l; subplan_itlist = build_tlist_index(subplan->targetlist); output_targetlist = NIL; foreach(l, plan->targetlist) { TargetEntry *tle = (TargetEntry *) lfirst(l); Node *newexpr; newexpr = fix_upper_expr((Node *) tle->expr, subplan_itlist, rtoffset); tle = flatCopyTargetEntry(tle); tle->expr = (Expr *) newexpr; output_targetlist = lappend(output_targetlist, tle); } plan->targetlist = output_targetlist; plan->qual = (List *) fix_upper_expr((Node *) plan->qual, subplan_itlist, rtoffset); pfree(subplan_itlist); } /* * set_dummy_tlist_references * Replace the targetlist of an upper-level plan node with a simple * list of OUTER references to its child. * * This is used for plan types like Sort and Append that don't evaluate * their targetlists. Although the executor doesn't care at all what's in * the tlist, EXPLAIN needs it to be realistic. * * Note: we could almost use set_upper_references() here, but it fails for * Append for lack of a lefttree subplan. Single-purpose code is faster * anyway. */ static void set_dummy_tlist_references(Plan *plan, int rtoffset) { List *output_targetlist; ListCell *l; output_targetlist = NIL; foreach(l, plan->targetlist) { TargetEntry *tle = (TargetEntry *) lfirst(l); Var *oldvar = (Var *) tle->expr; Var *newvar; newvar = makeVar(OUTER, tle->resno, exprType((Node *) oldvar), exprTypmod((Node *) oldvar), 0); if (IsA(oldvar, Var)) { newvar->varnoold = oldvar->varno + rtoffset; newvar->varoattno = oldvar->varattno; } else { newvar->varnoold = 0; /* wasn't ever a plain Var */ newvar->varoattno = 0; } tle = flatCopyTargetEntry(tle); tle->expr = (Expr *) newvar; output_targetlist = lappend(output_targetlist, tle); } plan->targetlist = output_targetlist; /* We don't touch plan->qual here */ } /* * build_tlist_index --- build an index data structure for a child tlist * * In most cases, subplan tlists will be "flat" tlists with only Vars, * so we try to optimize that case by extracting information about Vars * in advance. Matching a parent tlist to a child is still an O(N^2) * operation, but at least with a much smaller constant factor than plain * tlist_member() searches. * * The result of this function is an indexed_tlist struct to pass to * search_indexed_tlist_for_var() or search_indexed_tlist_for_non_var(). * When done, the indexed_tlist may be freed with a single pfree(). */ static indexed_tlist * build_tlist_index(List *tlist) { indexed_tlist *itlist; tlist_vinfo *vinfo; ListCell *l; /* Create data structure with enough slots for all tlist entries */ itlist = (indexed_tlist *) palloc(offsetof(indexed_tlist, vars) + list_length(tlist) * sizeof(tlist_vinfo)); itlist->tlist = tlist; itlist->has_non_vars = false; /* Find the Vars and fill in the index array */ vinfo = itlist->vars; foreach(l, tlist) { TargetEntry *tle = (TargetEntry *) lfirst(l); if (tle->expr && IsA(tle->expr, Var)) { Var *var = (Var *) tle->expr; vinfo->varno = var->varno; vinfo->varattno = var->varattno; vinfo->resno = tle->resno; vinfo++; } else itlist->has_non_vars = true; } itlist->num_vars = (vinfo - itlist->vars); return itlist; } /* * build_tlist_index_other_vars --- build a restricted tlist index * * This is like build_tlist_index, but we only index tlist entries that * are Vars and belong to some rel other than the one specified. */ static indexed_tlist * build_tlist_index_other_vars(List *tlist, Index ignore_rel) { indexed_tlist *itlist; tlist_vinfo *vinfo; ListCell *l; /* Create data structure with enough slots for all tlist entries */ itlist = (indexed_tlist *) palloc(offsetof(indexed_tlist, vars) + list_length(tlist) * sizeof(tlist_vinfo)); itlist->tlist = tlist; itlist->has_non_vars = false; /* Find the desired Vars and fill in the index array */ vinfo = itlist->vars; foreach(l, tlist) { TargetEntry *tle = (TargetEntry *) lfirst(l); if (tle->expr && IsA(tle->expr, Var)) { Var *var = (Var *) tle->expr; if (var->varno != ignore_rel) { vinfo->varno = var->varno; vinfo->varattno = var->varattno; vinfo->resno = tle->resno; vinfo++; } } } itlist->num_vars = (vinfo - itlist->vars); return itlist; } /* * search_indexed_tlist_for_var --- find a Var in an indexed tlist * * If a match is found, return a copy of the given Var with suitably * modified varno/varattno (to wit, newvarno and the resno of the TLE entry). * Also ensure that varnoold is incremented by rtoffset. * If no match, return NULL. */ static Var * search_indexed_tlist_for_var(Var *var, indexed_tlist *itlist, Index newvarno, int rtoffset) { Index varno = var->varno; AttrNumber varattno = var->varattno; tlist_vinfo *vinfo; int i; vinfo = itlist->vars; i = itlist->num_vars; while (i-- > 0) { if (vinfo->varno == varno && vinfo->varattno == varattno) { /* Found a match */ Var *newvar = copyVar(var); newvar->varno = newvarno; newvar->varattno = vinfo->resno; if (newvar->varnoold > 0) newvar->varnoold += rtoffset; return newvar; } vinfo++; } return NULL; /* no match */ } /* * search_indexed_tlist_for_non_var --- find a non-Var in an indexed tlist * * If a match is found, return a Var constructed to reference the tlist item. * If no match, return NULL. * * NOTE: it is a waste of time to call this if !itlist->has_non_vars */ static Var * search_indexed_tlist_for_non_var(Node *node, indexed_tlist *itlist, Index newvarno) { TargetEntry *tle; tle = tlist_member(node, itlist->tlist); if (tle) { /* Found a matching subplan output expression */ Var *newvar; newvar = makeVar(newvarno, tle->resno, exprType((Node *) tle->expr), exprTypmod((Node *) tle->expr), 0); newvar->varnoold = 0; /* wasn't ever a plain Var */ newvar->varoattno = 0; return newvar; } return NULL; /* no match */ } /* * fix_join_expr * Create a new set of targetlist entries or join qual clauses by * changing the varno/varattno values of variables in the clauses * to reference target list values from the outer and inner join * relation target lists. Also perform opcode lookup. * * This is used in two different scenarios: a normal join clause, where * all the Vars in the clause *must* be replaced by OUTER or INNER references; * and an indexscan being used on the inner side of a nestloop join. * In the latter case we want to replace the outer-relation Vars by OUTER * references, while Vars of the inner relation should be adjusted by rtoffset. * (We also implement RETURNING clause fixup using this second scenario.) * * For a normal join, acceptable_rel should be zero so that any failure to * match a Var will be reported as an error. For the indexscan case, * pass inner_itlist = NULL and acceptable_rel = the (not-offseted-yet) ID * of the inner relation. * * 'clauses' is the targetlist or list of join clauses * 'outer_itlist' is the indexed target list of the outer join relation * 'inner_itlist' is the indexed target list of the inner join relation, * or NULL * 'acceptable_rel' is either zero or the rangetable index of a relation * whose Vars may appear in the clause without provoking an error. * 'rtoffset' is what to add to varno for Vars of acceptable_rel. * * Returns the new expression tree. The original clause structure is * not modified. */ static List * fix_join_expr(List *clauses, indexed_tlist *outer_itlist, indexed_tlist *inner_itlist, Index acceptable_rel, int rtoffset) { fix_join_expr_context context; context.outer_itlist = outer_itlist; context.inner_itlist = inner_itlist; context.acceptable_rel = acceptable_rel; context.rtoffset = rtoffset; return (List *) fix_join_expr_mutator((Node *) clauses, &context); } static Node * fix_join_expr_mutator(Node *node, fix_join_expr_context *context) { Var *newvar; if (node == NULL) return NULL; if (IsA(node, Var)) { Var *var = (Var *) node; /* First look for the var in the input tlists */ newvar = search_indexed_tlist_for_var(var, context->outer_itlist, OUTER, context->rtoffset); if (newvar) return (Node *) newvar; if (context->inner_itlist) { newvar = search_indexed_tlist_for_var(var, context->inner_itlist, INNER, context->rtoffset); if (newvar) return (Node *) newvar; } /* If it's for acceptable_rel, adjust and return it */ if (var->varno == context->acceptable_rel) { var = copyVar(var); var->varno += context->rtoffset; var->varnoold += context->rtoffset; return (Node *) var; } /* No referent found for Var */ elog(ERROR, "variable not found in subplan target lists"); } /* Try matching more complex expressions too, if tlists have any */ if (context->outer_itlist->has_non_vars) { newvar = search_indexed_tlist_for_non_var(node, context->outer_itlist, OUTER); if (newvar) return (Node *) newvar; } if (context->inner_itlist && context->inner_itlist->has_non_vars) { newvar = search_indexed_tlist_for_non_var(node, context->inner_itlist, INNER); if (newvar) return (Node *) newvar; } /* * Since we update opcode info in-place, this part could possibly * scribble on the planner's input data structures, but it's OK. */ if (IsA(node, OpExpr)) set_opfuncid((OpExpr *) node); else if (IsA(node, DistinctExpr)) set_opfuncid((OpExpr *) node); /* rely on struct equivalence */ else if (IsA(node, NullIfExpr)) set_opfuncid((OpExpr *) node); /* rely on struct equivalence */ else if (IsA(node, ScalarArrayOpExpr)) set_sa_opfuncid((ScalarArrayOpExpr *) node); return expression_tree_mutator(node, fix_join_expr_mutator, (void *) context); } /* * fix_upper_expr * Modifies an expression tree so that all Var nodes reference outputs * of a subplan. Also performs opcode lookup. * * This is used to fix up target and qual expressions of non-join upper-level * plan nodes. * * An error is raised if no matching var can be found in the subplan tlist * --- so this routine should only be applied to nodes whose subplans' * targetlists were generated via flatten_tlist() or some such method. * * If itlist->has_non_vars is true, then we try to match whole subexpressions * against elements of the subplan tlist, so that we can avoid recomputing * expressions that were already computed by the subplan. (This is relatively * expensive, so we don't want to try it in the common case where the * subplan tlist is just a flattened list of Vars.) * * 'node': the tree to be fixed (a target item or qual) * 'subplan_itlist': indexed target list for subplan * 'rtoffset': how much to increment varnoold by * * The resulting tree is a copy of the original in which all Var nodes have * varno = OUTER, varattno = resno of corresponding subplan target. * The original tree is not modified. */ static Node * fix_upper_expr(Node *node, indexed_tlist *subplan_itlist, int rtoffset) { fix_upper_expr_context context; context.subplan_itlist = subplan_itlist; context.rtoffset = rtoffset; return fix_upper_expr_mutator(node, &context); } static Node * fix_upper_expr_mutator(Node *node, fix_upper_expr_context *context) { Var *newvar; if (node == NULL) return NULL; if (IsA(node, Var)) { Var *var = (Var *) node; newvar = search_indexed_tlist_for_var(var, context->subplan_itlist, OUTER, context->rtoffset); if (!newvar) elog(ERROR, "variable not found in subplan target list"); return (Node *) newvar; } /* Try matching more complex expressions too, if tlist has any */ if (context->subplan_itlist->has_non_vars) { newvar = search_indexed_tlist_for_non_var(node, context->subplan_itlist, OUTER); if (newvar) return (Node *) newvar; } /* * Since we update opcode info in-place, this part could possibly * scribble on the planner's input data structures, but it's OK. */ if (IsA(node, OpExpr)) set_opfuncid((OpExpr *) node); else if (IsA(node, DistinctExpr)) set_opfuncid((OpExpr *) node); /* rely on struct equivalence */ else if (IsA(node, NullIfExpr)) set_opfuncid((OpExpr *) node); /* rely on struct equivalence */ else if (IsA(node, ScalarArrayOpExpr)) set_sa_opfuncid((ScalarArrayOpExpr *) node); return expression_tree_mutator(node, fix_upper_expr_mutator, (void *) context); } /* * set_returning_clause_references * Perform setrefs.c's work on a RETURNING targetlist * * If the query involves more than just the result table, we have to * adjust any Vars that refer to other tables to reference junk tlist * entries in the top plan's targetlist. Vars referencing the result * table should be left alone, however (the executor will evaluate them * using the actual heap tuple, after firing triggers if any). In the * adjusted RETURNING list, result-table Vars will still have their * original varno, but Vars for other rels will have varno OUTER. * * We also must perform opcode lookup. * * 'rlist': the RETURNING targetlist to be fixed * 'topplan': the top Plan node for the query (not yet passed through * set_plan_references) * 'resultRelation': RT index of the associated result relation * * Note: we assume that result relations will have rtoffset zero, that is, * they are not coming from a subplan. */ List * set_returning_clause_references(List *rlist, Plan *topplan, Index resultRelation) { indexed_tlist *itlist; /* * We can perform the desired Var fixup by abusing the fix_join_expr * machinery that normally handles inner indexscan fixup. We search the * top plan's targetlist for Vars of non-result relations, and use * fix_join_expr to convert RETURNING Vars into references to those * tlist entries, while leaving result-rel Vars as-is. */ itlist = build_tlist_index_other_vars(topplan->targetlist, resultRelation); rlist = fix_join_expr(rlist, itlist, NULL, resultRelation, 0); pfree(itlist); return rlist; } /***************************************************************************** * OPERATOR REGPROC LOOKUP *****************************************************************************/ /* * fix_opfuncids * Calculate opfuncid field from opno for each OpExpr node in given tree. * The given tree can be anything expression_tree_walker handles. * * The argument is modified in-place. (This is OK since we'd want the * same change for any node, even if it gets visited more than once due to * shared structure.) */ void fix_opfuncids(Node *node) { /* This tree walk requires no special setup, so away we go... */ fix_opfuncids_walker(node, NULL); } static bool fix_opfuncids_walker(Node *node, void *context) { if (node == NULL) return false; if (IsA(node, OpExpr)) set_opfuncid((OpExpr *) node); else if (IsA(node, DistinctExpr)) set_opfuncid((OpExpr *) node); /* rely on struct equivalence */ else if (IsA(node, NullIfExpr)) set_opfuncid((OpExpr *) node); /* rely on struct equivalence */ else if (IsA(node, ScalarArrayOpExpr)) set_sa_opfuncid((ScalarArrayOpExpr *) node); return expression_tree_walker(node, fix_opfuncids_walker, context); } /* * set_opfuncid * Set the opfuncid (procedure OID) in an OpExpr node, * if it hasn't been set already. * * Because of struct equivalence, this can also be used for * DistinctExpr and NullIfExpr nodes. */ void set_opfuncid(OpExpr *opexpr) { if (opexpr->opfuncid == InvalidOid) opexpr->opfuncid = get_opcode(opexpr->opno); } /* * set_sa_opfuncid * As above, for ScalarArrayOpExpr nodes. */ void set_sa_opfuncid(ScalarArrayOpExpr *opexpr) { if (opexpr->opfuncid == InvalidOid) opexpr->opfuncid = get_opcode(opexpr->opno); }