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Diffstat (limited to 'src/backend/optimizer/util/paramassign.c')
| -rw-r--r-- | src/backend/optimizer/util/paramassign.c | 591 |
1 files changed, 591 insertions, 0 deletions
diff --git a/src/backend/optimizer/util/paramassign.c b/src/backend/optimizer/util/paramassign.c new file mode 100644 index 0000000..ebb4241 --- /dev/null +++ b/src/backend/optimizer/util/paramassign.c @@ -0,0 +1,591 @@ +/*------------------------------------------------------------------------- + * + * paramassign.c + * Functions for assigning PARAM_EXEC slots during planning. + * + * This module is responsible for managing three planner data structures: + * + * root->glob->paramExecTypes: records actual assignments of PARAM_EXEC slots. + * The i'th list element holds the data type OID of the i'th parameter slot. + * (Elements can be InvalidOid if they represent slots that are needed for + * chgParam signaling, but will never hold a value at runtime.) This list is + * global to the whole plan since the executor has only one PARAM_EXEC array. + * Assignments are permanent for the plan: we never remove entries once added. + * + * root->plan_params: a list of PlannerParamItem nodes, recording Vars and + * PlaceHolderVars that the root's query level needs to supply to lower-level + * subqueries, along with the PARAM_EXEC number to use for each such value. + * Elements are added to this list while planning a subquery, and the list + * is reset to empty after completion of each subquery. + * + * root->curOuterParams: a list of NestLoopParam nodes, recording Vars and + * PlaceHolderVars that some outer level of nestloop needs to pass down to + * a lower-level plan node in its righthand side. Elements are added to this + * list as createplan.c creates lower Plan nodes that need such Params, and + * are removed when it creates a NestLoop Plan node that will supply those + * values. + * + * The latter two data structures are used to prevent creating multiple + * PARAM_EXEC slots (each requiring work to fill) when the same upper + * SubPlan or NestLoop supplies a value that is referenced in more than + * one place in its child plan nodes. However, when the same Var has to + * be supplied to different subplan trees by different SubPlan or NestLoop + * parent nodes, we don't recognize any commonality; a fresh plan_params or + * curOuterParams entry will be made (since the old one has been removed + * when we finished processing the earlier SubPlan or NestLoop) and a fresh + * PARAM_EXEC number will be assigned. At one time we tried to avoid + * allocating duplicate PARAM_EXEC numbers in such cases, but it's harder + * than it seems to avoid bugs due to overlapping Param lifetimes, so we + * don't risk that anymore. Minimizing the number of PARAM_EXEC slots + * doesn't really save much executor work anyway. + * + * + * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group + * Portions Copyright (c) 1994, Regents of the University of California + * + * IDENTIFICATION + * src/backend/optimizer/util/paramassign.c + * + *------------------------------------------------------------------------- + */ +#include "postgres.h" + +#include "nodes/nodeFuncs.h" +#include "nodes/plannodes.h" +#include "optimizer/paramassign.h" +#include "optimizer/placeholder.h" +#include "rewrite/rewriteManip.h" + + +/* + * Select a PARAM_EXEC number to identify the given Var as a parameter for + * the current subquery. (It might already have one.) + * Record the need for the Var in the proper upper-level root->plan_params. + */ +static int +assign_param_for_var(PlannerInfo *root, Var *var) +{ + ListCell *ppl; + PlannerParamItem *pitem; + Index levelsup; + + /* Find the query level the Var belongs to */ + for (levelsup = var->varlevelsup; levelsup > 0; levelsup--) + root = root->parent_root; + + /* If there's already a matching PlannerParamItem there, just use it */ + foreach(ppl, root->plan_params) + { + pitem = (PlannerParamItem *) lfirst(ppl); + if (IsA(pitem->item, Var)) + { + Var *pvar = (Var *) pitem->item; + + /* + * This comparison must match _equalVar(), except for ignoring + * varlevelsup. Note that _equalVar() ignores varnosyn, + * varattnosyn, and location, so this does too. + */ + if (pvar->varno == var->varno && + pvar->varattno == var->varattno && + pvar->vartype == var->vartype && + pvar->vartypmod == var->vartypmod && + pvar->varcollid == var->varcollid) + return pitem->paramId; + } + } + + /* Nope, so make a new one */ + var = copyObject(var); + var->varlevelsup = 0; + + pitem = makeNode(PlannerParamItem); + pitem->item = (Node *) var; + pitem->paramId = list_length(root->glob->paramExecTypes); + root->glob->paramExecTypes = lappend_oid(root->glob->paramExecTypes, + var->vartype); + + root->plan_params = lappend(root->plan_params, pitem); + + return pitem->paramId; +} + +/* + * Generate a Param node to replace the given Var, + * which is expected to have varlevelsup > 0 (ie, it is not local). + * Record the need for the Var in the proper upper-level root->plan_params. + */ +Param * +replace_outer_var(PlannerInfo *root, Var *var) +{ + Param *retval; + int i; + + Assert(var->varlevelsup > 0 && var->varlevelsup < root->query_level); + + /* Find the Var in the appropriate plan_params, or add it if not present */ + i = assign_param_for_var(root, var); + + retval = makeNode(Param); + retval->paramkind = PARAM_EXEC; + retval->paramid = i; + retval->paramtype = var->vartype; + retval->paramtypmod = var->vartypmod; + retval->paramcollid = var->varcollid; + retval->location = var->location; + + return retval; +} + +/* + * Select a PARAM_EXEC number to identify the given PlaceHolderVar as a + * parameter for the current subquery. (It might already have one.) + * Record the need for the PHV in the proper upper-level root->plan_params. + * + * This is just like assign_param_for_var, except for PlaceHolderVars. + */ +static int +assign_param_for_placeholdervar(PlannerInfo *root, PlaceHolderVar *phv) +{ + ListCell *ppl; + PlannerParamItem *pitem; + Index levelsup; + + /* Find the query level the PHV belongs to */ + for (levelsup = phv->phlevelsup; levelsup > 0; levelsup--) + root = root->parent_root; + + /* If there's already a matching PlannerParamItem there, just use it */ + foreach(ppl, root->plan_params) + { + pitem = (PlannerParamItem *) lfirst(ppl); + if (IsA(pitem->item, PlaceHolderVar)) + { + PlaceHolderVar *pphv = (PlaceHolderVar *) pitem->item; + + /* We assume comparing the PHIDs is sufficient */ + if (pphv->phid == phv->phid) + return pitem->paramId; + } + } + + /* Nope, so make a new one */ + phv = copyObject(phv); + IncrementVarSublevelsUp((Node *) phv, -((int) phv->phlevelsup), 0); + Assert(phv->phlevelsup == 0); + + pitem = makeNode(PlannerParamItem); + pitem->item = (Node *) phv; + pitem->paramId = list_length(root->glob->paramExecTypes); + root->glob->paramExecTypes = lappend_oid(root->glob->paramExecTypes, + exprType((Node *) phv->phexpr)); + + root->plan_params = lappend(root->plan_params, pitem); + + return pitem->paramId; +} + +/* + * Generate a Param node to replace the given PlaceHolderVar, + * which is expected to have phlevelsup > 0 (ie, it is not local). + * Record the need for the PHV in the proper upper-level root->plan_params. + * + * This is just like replace_outer_var, except for PlaceHolderVars. + */ +Param * +replace_outer_placeholdervar(PlannerInfo *root, PlaceHolderVar *phv) +{ + Param *retval; + int i; + + Assert(phv->phlevelsup > 0 && phv->phlevelsup < root->query_level); + + /* Find the PHV in the appropriate plan_params, or add it if not present */ + i = assign_param_for_placeholdervar(root, phv); + + retval = makeNode(Param); + retval->paramkind = PARAM_EXEC; + retval->paramid = i; + retval->paramtype = exprType((Node *) phv->phexpr); + retval->paramtypmod = exprTypmod((Node *) phv->phexpr); + retval->paramcollid = exprCollation((Node *) phv->phexpr); + retval->location = -1; + + return retval; +} + +/* + * Generate a Param node to replace the given Aggref + * which is expected to have agglevelsup > 0 (ie, it is not local). + * Record the need for the Aggref in the proper upper-level root->plan_params. + */ +Param * +replace_outer_agg(PlannerInfo *root, Aggref *agg) +{ + Param *retval; + PlannerParamItem *pitem; + Index levelsup; + + Assert(agg->agglevelsup > 0 && agg->agglevelsup < root->query_level); + + /* Find the query level the Aggref belongs to */ + for (levelsup = agg->agglevelsup; levelsup > 0; levelsup--) + root = root->parent_root; + + /* + * It does not seem worthwhile to try to de-duplicate references to outer + * aggs. Just make a new slot every time. + */ + agg = copyObject(agg); + IncrementVarSublevelsUp((Node *) agg, -((int) agg->agglevelsup), 0); + Assert(agg->agglevelsup == 0); + + pitem = makeNode(PlannerParamItem); + pitem->item = (Node *) agg; + pitem->paramId = list_length(root->glob->paramExecTypes); + root->glob->paramExecTypes = lappend_oid(root->glob->paramExecTypes, + agg->aggtype); + + root->plan_params = lappend(root->plan_params, pitem); + + retval = makeNode(Param); + retval->paramkind = PARAM_EXEC; + retval->paramid = pitem->paramId; + retval->paramtype = agg->aggtype; + retval->paramtypmod = -1; + retval->paramcollid = agg->aggcollid; + retval->location = agg->location; + + return retval; +} + +/* + * Generate a Param node to replace the given GroupingFunc expression which is + * expected to have agglevelsup > 0 (ie, it is not local). + * Record the need for the GroupingFunc in the proper upper-level + * root->plan_params. + */ +Param * +replace_outer_grouping(PlannerInfo *root, GroupingFunc *grp) +{ + Param *retval; + PlannerParamItem *pitem; + Index levelsup; + Oid ptype = exprType((Node *) grp); + + Assert(grp->agglevelsup > 0 && grp->agglevelsup < root->query_level); + + /* Find the query level the GroupingFunc belongs to */ + for (levelsup = grp->agglevelsup; levelsup > 0; levelsup--) + root = root->parent_root; + + /* + * It does not seem worthwhile to try to de-duplicate references to outer + * aggs. Just make a new slot every time. + */ + grp = copyObject(grp); + IncrementVarSublevelsUp((Node *) grp, -((int) grp->agglevelsup), 0); + Assert(grp->agglevelsup == 0); + + pitem = makeNode(PlannerParamItem); + pitem->item = (Node *) grp; + pitem->paramId = list_length(root->glob->paramExecTypes); + root->glob->paramExecTypes = lappend_oid(root->glob->paramExecTypes, + ptype); + + root->plan_params = lappend(root->plan_params, pitem); + + retval = makeNode(Param); + retval->paramkind = PARAM_EXEC; + retval->paramid = pitem->paramId; + retval->paramtype = ptype; + retval->paramtypmod = -1; + retval->paramcollid = InvalidOid; + retval->location = grp->location; + + return retval; +} + +/* + * Generate a Param node to replace the given Var, + * which is expected to come from some upper NestLoop plan node. + * Record the need for the Var in root->curOuterParams. + */ +Param * +replace_nestloop_param_var(PlannerInfo *root, Var *var) +{ + Param *param; + NestLoopParam *nlp; + ListCell *lc; + + /* Is this Var already listed in root->curOuterParams? */ + foreach(lc, root->curOuterParams) + { + nlp = (NestLoopParam *) lfirst(lc); + if (equal(var, nlp->paramval)) + { + /* Yes, so just make a Param referencing this NLP's slot */ + param = makeNode(Param); + param->paramkind = PARAM_EXEC; + param->paramid = nlp->paramno; + param->paramtype = var->vartype; + param->paramtypmod = var->vartypmod; + param->paramcollid = var->varcollid; + param->location = var->location; + return param; + } + } + + /* No, so assign a PARAM_EXEC slot for a new NLP */ + param = generate_new_exec_param(root, + var->vartype, + var->vartypmod, + var->varcollid); + param->location = var->location; + + /* Add it to the list of required NLPs */ + nlp = makeNode(NestLoopParam); + nlp->paramno = param->paramid; + nlp->paramval = copyObject(var); + root->curOuterParams = lappend(root->curOuterParams, nlp); + + /* And return the replacement Param */ + return param; +} + +/* + * Generate a Param node to replace the given PlaceHolderVar, + * which is expected to come from some upper NestLoop plan node. + * Record the need for the PHV in root->curOuterParams. + * + * This is just like replace_nestloop_param_var, except for PlaceHolderVars. + */ +Param * +replace_nestloop_param_placeholdervar(PlannerInfo *root, PlaceHolderVar *phv) +{ + Param *param; + NestLoopParam *nlp; + ListCell *lc; + + /* Is this PHV already listed in root->curOuterParams? */ + foreach(lc, root->curOuterParams) + { + nlp = (NestLoopParam *) lfirst(lc); + if (equal(phv, nlp->paramval)) + { + /* Yes, so just make a Param referencing this NLP's slot */ + param = makeNode(Param); + param->paramkind = PARAM_EXEC; + param->paramid = nlp->paramno; + param->paramtype = exprType((Node *) phv->phexpr); + param->paramtypmod = exprTypmod((Node *) phv->phexpr); + param->paramcollid = exprCollation((Node *) phv->phexpr); + param->location = -1; + return param; + } + } + + /* No, so assign a PARAM_EXEC slot for a new NLP */ + param = generate_new_exec_param(root, + exprType((Node *) phv->phexpr), + exprTypmod((Node *) phv->phexpr), + exprCollation((Node *) phv->phexpr)); + + /* Add it to the list of required NLPs */ + nlp = makeNode(NestLoopParam); + nlp->paramno = param->paramid; + nlp->paramval = (Var *) copyObject(phv); + root->curOuterParams = lappend(root->curOuterParams, nlp); + + /* And return the replacement Param */ + return param; +} + +/* + * process_subquery_nestloop_params + * Handle params of a parameterized subquery that need to be fed + * from an outer nestloop. + * + * Currently, that would be *all* params that a subquery in FROM has demanded + * from the current query level, since they must be LATERAL references. + * + * subplan_params is a list of PlannerParamItems that we intend to pass to + * a subquery-in-FROM. (This was constructed in root->plan_params while + * planning the subquery, but isn't there anymore when this is called.) + * + * The subplan's references to the outer variables are already represented + * as PARAM_EXEC Params, since that conversion was done by the routines above + * while planning the subquery. So we need not modify the subplan or the + * PlannerParamItems here. What we do need to do is add entries to + * root->curOuterParams to signal the parent nestloop plan node that it must + * provide these values. This differs from replace_nestloop_param_var in + * that the PARAM_EXEC slots to use have already been determined. + * + * Note that we also use root->curOuterRels as an implicit parameter for + * sanity checks. + */ +void +process_subquery_nestloop_params(PlannerInfo *root, List *subplan_params) +{ + ListCell *lc; + + foreach(lc, subplan_params) + { + PlannerParamItem *pitem = castNode(PlannerParamItem, lfirst(lc)); + + if (IsA(pitem->item, Var)) + { + Var *var = (Var *) pitem->item; + NestLoopParam *nlp; + ListCell *lc; + + /* If not from a nestloop outer rel, complain */ + if (!bms_is_member(var->varno, root->curOuterRels)) + elog(ERROR, "non-LATERAL parameter required by subquery"); + + /* Is this param already listed in root->curOuterParams? */ + foreach(lc, root->curOuterParams) + { + nlp = (NestLoopParam *) lfirst(lc); + if (nlp->paramno == pitem->paramId) + { + Assert(equal(var, nlp->paramval)); + /* Present, so nothing to do */ + break; + } + } + if (lc == NULL) + { + /* No, so add it */ + nlp = makeNode(NestLoopParam); + nlp->paramno = pitem->paramId; + nlp->paramval = copyObject(var); + root->curOuterParams = lappend(root->curOuterParams, nlp); + } + } + else if (IsA(pitem->item, PlaceHolderVar)) + { + PlaceHolderVar *phv = (PlaceHolderVar *) pitem->item; + NestLoopParam *nlp; + ListCell *lc; + + /* If not from a nestloop outer rel, complain */ + if (!bms_is_subset(find_placeholder_info(root, phv, false)->ph_eval_at, + root->curOuterRels)) + elog(ERROR, "non-LATERAL parameter required by subquery"); + + /* Is this param already listed in root->curOuterParams? */ + foreach(lc, root->curOuterParams) + { + nlp = (NestLoopParam *) lfirst(lc); + if (nlp->paramno == pitem->paramId) + { + Assert(equal(phv, nlp->paramval)); + /* Present, so nothing to do */ + break; + } + } + if (lc == NULL) + { + /* No, so add it */ + nlp = makeNode(NestLoopParam); + nlp->paramno = pitem->paramId; + nlp->paramval = (Var *) copyObject(phv); + root->curOuterParams = lappend(root->curOuterParams, nlp); + } + } + else + elog(ERROR, "unexpected type of subquery parameter"); + } +} + +/* + * Identify any NestLoopParams that should be supplied by a NestLoop plan + * node with the specified lefthand rels. Remove them from the active + * root->curOuterParams list and return them as the result list. + */ +List * +identify_current_nestloop_params(PlannerInfo *root, Relids leftrelids) +{ + List *result; + ListCell *cell; + + result = NIL; + foreach(cell, root->curOuterParams) + { + NestLoopParam *nlp = (NestLoopParam *) lfirst(cell); + + /* + * We are looking for Vars and PHVs that can be supplied by the + * lefthand rels. The "bms_overlap" test is just an optimization to + * allow skipping find_placeholder_info() if the PHV couldn't match. + */ + if (IsA(nlp->paramval, Var) && + bms_is_member(nlp->paramval->varno, leftrelids)) + { + root->curOuterParams = foreach_delete_current(root->curOuterParams, + cell); + result = lappend(result, nlp); + } + else if (IsA(nlp->paramval, PlaceHolderVar) && + bms_overlap(((PlaceHolderVar *) nlp->paramval)->phrels, + leftrelids) && + bms_is_subset(find_placeholder_info(root, + (PlaceHolderVar *) nlp->paramval, + false)->ph_eval_at, + leftrelids)) + { + root->curOuterParams = foreach_delete_current(root->curOuterParams, + cell); + result = lappend(result, nlp); + } + } + return result; +} + +/* + * Generate a new Param node that will not conflict with any other. + * + * This is used to create Params representing subplan outputs or + * NestLoop parameters. + * + * We don't need to build a PlannerParamItem for such a Param, but we do + * need to make sure we record the type in paramExecTypes (otherwise, + * there won't be a slot allocated for it). + */ +Param * +generate_new_exec_param(PlannerInfo *root, Oid paramtype, int32 paramtypmod, + Oid paramcollation) +{ + Param *retval; + + retval = makeNode(Param); + retval->paramkind = PARAM_EXEC; + retval->paramid = list_length(root->glob->paramExecTypes); + root->glob->paramExecTypes = lappend_oid(root->glob->paramExecTypes, + paramtype); + retval->paramtype = paramtype; + retval->paramtypmod = paramtypmod; + retval->paramcollid = paramcollation; + retval->location = -1; + + return retval; +} + +/* + * Assign a (nonnegative) PARAM_EXEC ID for a special parameter (one that + * is not actually used to carry a value at runtime). Such parameters are + * used for special runtime signaling purposes, such as connecting a + * recursive union node to its worktable scan node or forcing plan + * re-evaluation within the EvalPlanQual mechanism. No actual Param node + * exists with this ID, however. + */ +int +assign_special_exec_param(PlannerInfo *root) +{ + int paramId = list_length(root->glob->paramExecTypes); + + root->glob->paramExecTypes = lappend_oid(root->glob->paramExecTypes, + InvalidOid); + return paramId; +} |