diff options
Diffstat (limited to 'src/include')
| -rw-r--r-- | src/include/nodes/relation.h | 71 |
1 files changed, 40 insertions, 31 deletions
diff --git a/src/include/nodes/relation.h b/src/include/nodes/relation.h index af9425ad9b3..2b2742d7ef5 100644 --- a/src/include/nodes/relation.h +++ b/src/include/nodes/relation.h @@ -75,8 +75,6 @@ typedef struct PlannerGlobal ParamListInfo boundParams; /* Param values provided to planner() */ - List *paramlist; /* to keep track of cross-level Params */ - List *subplans; /* Plans for SubPlan nodes */ List *subroots; /* PlannerInfos for SubPlan nodes */ @@ -93,6 +91,8 @@ typedef struct PlannerGlobal List *invalItems; /* other dependencies, as PlanInvalItems */ + int nParamExec; /* number of PARAM_EXEC Params used */ + Index lastPHId; /* highest PlaceHolderVar ID assigned */ Index lastRowMarkId; /* highest PlanRowMark ID assigned */ @@ -127,6 +127,8 @@ typedef struct PlannerInfo struct PlannerInfo *parent_root; /* NULL at outermost Query */ + List *plan_params; /* list of PlannerParamItems, see below */ + /* * simple_rel_array holds pointers to "base rels" and "other rels" (see * comments for RelOptInfo for more info). It is indexed by rangetable @@ -344,6 +346,7 @@ typedef struct PlannerInfo * allvisfrac - fraction of disk pages that are marked all-visible * subplan - plan for subquery (NULL if it's not a subquery) * subroot - PlannerInfo for subquery (NULL if it's not a subquery) + * subplan_params - list of PlannerParamItems to be passed to subquery * fdwroutine - function hooks for FDW, if foreign table (else NULL) * fdw_private - private state for FDW, if foreign table (else NULL) * @@ -436,6 +439,7 @@ typedef struct RelOptInfo /* use "struct Plan" to avoid including plannodes.h here */ struct Plan *subplan; /* if subquery */ PlannerInfo *subroot; /* if subquery */ + List *subplan_params; /* if subquery */ /* use "struct FdwRoutine" to avoid including fdwapi.h here */ struct FdwRoutine *fdwroutine; /* if foreign table */ void *fdw_private; /* if foreign table */ @@ -1507,23 +1511,26 @@ typedef struct MinMaxAggInfo } MinMaxAggInfo; /* - * glob->paramlist keeps track of the PARAM_EXEC slots that we have decided - * we need for the query. At runtime these slots are used to pass values - * around from one plan node to another. They can be used to pass values - * down into subqueries (for outer references in subqueries), or up out of - * subqueries (for the results of a subplan), or from a NestLoop plan node - * into its inner relation (when the inner scan is parameterized with values - * from the outer relation). The n'th entry in the list (n counts from 0) - * corresponds to Param->paramid = n. - * - * Each paramlist item shows the absolute query level it is associated with, - * where the outermost query is level 1 and nested subqueries have higher - * numbers. The item the parameter slot represents can be one of four kinds: - * - * A Var: the slot represents a variable of that level that must be passed + * At runtime, PARAM_EXEC slots are used to pass values around from one plan + * node to another. They can be used to pass values down into subqueries (for + * outer references in subqueries), or up out of subqueries (for the results + * of a subplan), or from a NestLoop plan node into its inner relation (when + * the inner scan is parameterized with values from the outer relation). + * The planner is responsible for assigning nonconflicting PARAM_EXEC IDs to + * the PARAM_EXEC Params it generates. + * + * Outer references are managed via root->plan_params, which is a list of + * PlannerParamItems. While planning a subquery, each parent query level's + * plan_params contains the values required from it by the current subquery. + * During create_plan(), we use plan_params to track values that must be + * passed from outer to inner sides of NestLoop plan nodes. + * + * The item a PlannerParamItem represents can be one of three kinds: + * + * A Var: the slot represents a variable of this level that must be passed * down because subqueries have outer references to it, or must be passed - * from a NestLoop node of that level to its inner scan. The varlevelsup - * value in the Var will always be zero. + * from a NestLoop node to its inner scan. The varlevelsup value in the Var + * will always be zero. * * A PlaceHolderVar: this works much like the Var case, except that the * entry is a PlaceHolderVar node with a contained expression. The PHV @@ -1535,25 +1542,27 @@ typedef struct MinMaxAggInfo * subquery. The Aggref itself has agglevelsup = 0, and its argument tree * is adjusted to match in level. * - * A Param: the slot holds the result of a subplan (it is a setParam item - * for that subplan). The absolute level shown for such items corresponds - * to the parent query of the subplan. - * * Note: we detect duplicate Var and PlaceHolderVar parameters and coalesce - * them into one slot, but we do not bother to do this for Aggrefs, and it - * would be incorrect to do so for Param slots. Duplicate detection is - * actually *necessary* for NestLoop parameters since it serves to match up - * the usage of a Param (in the inner scan) with the assignment of the value - * (in the NestLoop node). This might result in the same PARAM_EXEC slot being - * used by multiple NestLoop nodes or SubPlan nodes, but no harm is done since - * the same value would be assigned anyway. + * them into one slot, but we do not bother to do that for Aggrefs. + * The scope of duplicate-elimination only extends across the set of + * parameters passed from one query level into a single subquery, or for + * nestloop parameters across the set of nestloop parameters used in a single + * query level. So there is no possibility of a PARAM_EXEC slot being used + * for conflicting purposes. + * + * In addition, PARAM_EXEC slots are assigned for Params representing outputs + * from subplans (values that are setParam items for those subplans). These + * IDs need not be tracked via PlannerParamItems, since we do not need any + * duplicate-elimination nor later processing of the represented expressions. + * Instead, we just record the assignment of the slot number by incrementing + * root->glob->nParamExec. */ typedef struct PlannerParamItem { NodeTag type; - Node *item; /* the Var, PlaceHolderVar, Aggref, or Param */ - Index abslevel; /* its absolute query level */ + Node *item; /* the Var, PlaceHolderVar, or Aggref */ + int paramId; /* its assigned PARAM_EXEC slot number */ } PlannerParamItem; /* |