diff options
Diffstat (limited to 'src/include/nodes/relation.h')
| -rw-r--r-- | src/include/nodes/relation.h | 65 |
1 files changed, 35 insertions, 30 deletions
diff --git a/src/include/nodes/relation.h b/src/include/nodes/relation.h index bdea72c3f47..b48a6183dc2 100644 --- a/src/include/nodes/relation.h +++ b/src/include/nodes/relation.h @@ -62,34 +62,6 @@ typedef struct AggClauseCosts } AggClauseCosts; /* - * This struct contains what we need to know during planning about the - * targetlist (output columns) that a Path will compute. Each RelOptInfo - * includes a default PathTarget, which its individual Paths may merely point - * to. However, in some cases a Path may compute outputs different from other - * Paths, and in that case we make a custom PathTarget struct for it. For - * example, an indexscan might return index expressions that would otherwise - * need to be explicitly calculated. - * - * exprs contains bare expressions; they do not have TargetEntry nodes on top, - * though those will appear in finished Plans. - * - * sortgrouprefs[] is an array of the same length as exprs, containing the - * corresponding sort/group refnos, or zeroes for expressions not referenced - * by sort/group clauses. If sortgrouprefs is NULL (which it always is in - * RelOptInfo.reltarget structs; only upper-level Paths contain this info), we - * have not identified sort/group columns in this tlist. This allows us to - * deal with sort/group refnos when needed with less expense than including - * TargetEntry nodes in the exprs list. - */ -typedef struct PathTarget -{ - List *exprs; /* list of expressions to be computed */ - Index *sortgrouprefs; /* corresponding sort/group refnos, or 0 */ - QualCost cost; /* cost of evaluating the expressions */ - int width; /* estimated avg width of result tuples */ -} PathTarget; - -/* * This enum identifies the different types of "upper" (post-scan/join) * relations that we might deal with during planning. */ @@ -514,7 +486,7 @@ typedef struct RelOptInfo bool consider_parallel; /* consider parallel paths? */ /* default result targetlist for Paths scanning this relation */ - PathTarget reltarget; /* list of Vars/Exprs, cost, width */ + struct PathTarget *reltarget; /* list of Vars/Exprs, cost, width */ /* materialization information */ List *pathlist; /* Path structures */ @@ -766,6 +738,39 @@ typedef struct PathKey /* + * PathTarget + * + * This struct contains what we need to know during planning about the + * targetlist (output columns) that a Path will compute. Each RelOptInfo + * includes a default PathTarget, which its individual Paths may simply + * reference. However, in some cases a Path may compute outputs different + * from other Paths, and in that case we make a custom PathTarget for it. + * For example, an indexscan might return index expressions that would + * otherwise need to be explicitly calculated. (Note also that "upper" + * relations generally don't have useful default PathTargets.) + * + * exprs contains bare expressions; they do not have TargetEntry nodes on top, + * though those will appear in finished Plans. + * + * sortgrouprefs[] is an array of the same length as exprs, containing the + * corresponding sort/group refnos, or zeroes for expressions not referenced + * by sort/group clauses. If sortgrouprefs is NULL (which it generally is in + * RelOptInfo.reltarget targets; only upper-level Paths contain this info), + * we have not identified sort/group columns in this tlist. This allows us to + * deal with sort/group refnos when needed with less expense than including + * TargetEntry nodes in the exprs list. + */ +typedef struct PathTarget +{ + NodeTag type; + List *exprs; /* list of expressions to be computed */ + Index *sortgrouprefs; /* corresponding sort/group refnos, or 0 */ + QualCost cost; /* cost of evaluating the expressions */ + int width; /* estimated avg width of result tuples */ +} PathTarget; + + +/* * ParamPathInfo * * All parameterized paths for a given relation with given required outer rels @@ -802,7 +807,7 @@ typedef struct ParamPathInfo * "parent" identifies the relation this Path scans, and "pathtarget" * describes the precise set of output columns the Path would compute. * In simple cases all Paths for a given rel share the same targetlist, - * which we represent by having path->pathtarget point to parent->reltarget. + * which we represent by having path->pathtarget equal to parent->reltarget. * * "param_info", if not NULL, links to a ParamPathInfo that identifies outer * relation(s) that provide parameter values to each scan of this path. |