diff options
Diffstat (limited to 'src/include')
| -rw-r--r-- | src/include/nodes/plannodes.h | 4 | ||||
| -rw-r--r-- | src/include/nodes/relation.h | 21 | ||||
| -rw-r--r-- | src/include/optimizer/subselect.h | 4 |
3 files changed, 18 insertions, 11 deletions
diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h index ababded845a..66858644b38 100644 --- a/src/include/nodes/plannodes.h +++ b/src/include/nodes/plannodes.h @@ -508,7 +508,9 @@ typedef struct Join * The nestParams list identifies any executor Params that must be passed * into execution of the inner subplan carrying values from the current row * of the outer subplan. Currently we restrict these values to be simple - * Vars, but perhaps someday that'd be worth relaxing. + * Vars, but perhaps someday that'd be worth relaxing. (Note: during plan + * creation, the paramval can actually be a PlaceHolderVar expression; but it + * must be a Var with varno OUTER_VAR by the time it gets to the executor.) * ---------------- */ typedef struct NestLoop diff --git a/src/include/nodes/relation.h b/src/include/nodes/relation.h index ede97571e06..a400960a272 100644 --- a/src/include/nodes/relation.h +++ b/src/include/nodes/relation.h @@ -1439,13 +1439,16 @@ typedef struct MinMaxAggInfo * * 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 three kinds: + * 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 * 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. * + * A PlaceHolderVar: this works much like the Var case. It is currently + * only needed for NestLoop parameters, not outer references. + * * An Aggref (with an expression tree representing its argument): the slot * represents an aggregate expression that is an outer reference for some * subquery. The Aggref itself has agglevelsup = 0, and its argument tree @@ -1455,20 +1458,20 @@ typedef struct MinMaxAggInfo * for that subplan). The absolute level shown for such items corresponds * to the parent query of the subplan. * - * Note: we detect duplicate Var 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* - * in the case of 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 + * 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. */ typedef struct PlannerParamItem { NodeTag type; - Node *item; /* the Var, Aggref, or Param */ + Node *item; /* the Var, PlaceHolderVar, Aggref, or Param */ Index abslevel; /* its absolute query level */ } PlannerParamItem; diff --git a/src/include/optimizer/subselect.h b/src/include/optimizer/subselect.h index ff9e2b7f89f..564865ad68f 100644 --- a/src/include/optimizer/subselect.h +++ b/src/include/optimizer/subselect.h @@ -29,7 +29,9 @@ extern void SS_finalize_plan(PlannerInfo *root, Plan *plan, bool attach_initplans); extern Param *SS_make_initplan_from_plan(PlannerInfo *root, Plan *plan, Oid resulttype, int32 resulttypmod, Oid resultcollation); -extern Param *assign_nestloop_param(PlannerInfo *root, Var *var); +extern Param *assign_nestloop_param_var(PlannerInfo *root, Var *var); +extern Param *assign_nestloop_param_placeholdervar(PlannerInfo *root, + PlaceHolderVar *phv); extern int SS_assign_special_param(PlannerInfo *root); #endif /* SUBSELECT_H */ |