diff options
Diffstat (limited to 'src/include/nodes/relation.h')
| -rw-r--r-- | src/include/nodes/relation.h | 26 |
1 files changed, 20 insertions, 6 deletions
diff --git a/src/include/nodes/relation.h b/src/include/nodes/relation.h index a684f192220..3374e5fae74 100644 --- a/src/include/nodes/relation.h +++ b/src/include/nodes/relation.h @@ -7,7 +7,7 @@ * Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * - * $PostgreSQL: pgsql/src/include/nodes/relation.h,v 1.187 2010/07/06 19:19:00 momjian Exp $ + * $PostgreSQL: pgsql/src/include/nodes/relation.h,v 1.188 2010/07/12 17:01:06 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -209,6 +209,10 @@ typedef struct PlannerInfo int wt_param_id; /* PARAM_EXEC ID for the work table */ struct Plan *non_recursive_plan; /* plan for non-recursive term */ + /* These fields are workspace for createplan.c */ + Relids curOuterRels; /* outer rels above current node */ + List *curOuterParams; /* not-yet-assigned NestLoopParams */ + /* optional private data for join_search_hook, e.g., GEQO */ void *join_search_private; } PlannerInfo; @@ -1330,16 +1334,20 @@ typedef struct PlaceHolderInfo /* * 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 - * either down into subqueries (for outer references in subqueries) or up out - * of subqueries (for the results of a subplan). The n'th entry in the list - * (n counts from 0) corresponds to Param->paramid = n. + * 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 three kinds: * * A Var: the slot represents a variable of that level that must be passed - * down because subqueries have outer references to it. The varlevelsup + * 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. * * An Aggref (with an expression tree representing its argument): the slot @@ -1352,7 +1360,13 @@ typedef struct PlaceHolderInfo * to the parent query of the subplan. * * Note: we detect duplicate Var parameters and coalesce them into one slot, - * but we do not do this for Aggref or Param slots. + * 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 + * the same value would be assigned anyway. */ typedef struct PlannerParamItem { |