diff options
Diffstat (limited to 'src/backend/optimizer/plan/createplan.c')
| -rw-r--r-- | src/backend/optimizer/plan/createplan.c | 62 |
1 files changed, 58 insertions, 4 deletions
diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c index a243ca80d2d..be4d79f1bf2 100644 --- a/src/backend/optimizer/plan/createplan.c +++ b/src/backend/optimizer/plan/createplan.c @@ -10,7 +10,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/optimizer/plan/createplan.c,v 1.255 2009/01/01 17:23:44 momjian Exp $ + * $PostgreSQL: pgsql/src/backend/optimizer/plan/createplan.c,v 1.256 2009/03/21 00:04:39 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -112,7 +112,11 @@ static HashJoin *make_hashjoin(List *tlist, List *hashclauses, Plan *lefttree, Plan *righttree, JoinType jointype); -static Hash *make_hash(Plan *lefttree); +static Hash *make_hash(Plan *lefttree, + Oid skewTable, + AttrNumber skewColumn, + Oid skewColType, + int32 skewColTypmod); static MergeJoin *make_mergejoin(List *tlist, List *joinclauses, List *otherclauses, List *mergeclauses, @@ -1864,6 +1868,10 @@ create_hashjoin_plan(PlannerInfo *root, List *joinclauses; List *otherclauses; List *hashclauses; + Oid skewTable = InvalidOid; + AttrNumber skewColumn = InvalidAttrNumber; + Oid skewColType = InvalidOid; + int32 skewColTypmod = -1; HashJoin *join_plan; Hash *hash_plan; @@ -1903,9 +1911,46 @@ create_hashjoin_plan(PlannerInfo *root, disuse_physical_tlist(inner_plan, best_path->jpath.innerjoinpath); /* + * If there is a single join clause and we can identify the outer + * variable as a simple column reference, supply its identity for + * possible use in skew optimization. (Note: in principle we could + * do skew optimization with multiple join clauses, but we'd have to + * be able to determine the most common combinations of outer values, + * which we don't currently have enough stats for.) + */ + if (list_length(hashclauses) == 1) + { + OpExpr *clause = (OpExpr *) linitial(hashclauses); + Node *node; + + Assert(is_opclause(clause)); + node = (Node *) linitial(clause->args); + if (IsA(node, RelabelType)) + node = (Node *) ((RelabelType *) node)->arg; + if (IsA(node, Var)) + { + Var *var = (Var *) node; + RangeTblEntry *rte; + + rte = root->simple_rte_array[var->varno]; + if (rte->rtekind == RTE_RELATION) + { + skewTable = rte->relid; + skewColumn = var->varattno; + skewColType = var->vartype; + skewColTypmod = var->vartypmod; + } + } + } + + /* * Build the hash node and hash join node. */ - hash_plan = make_hash(inner_plan); + hash_plan = make_hash(inner_plan, + skewTable, + skewColumn, + skewColType, + skewColTypmod); join_plan = make_hashjoin(tlist, joinclauses, otherclauses, @@ -2713,7 +2758,11 @@ make_hashjoin(List *tlist, } static Hash * -make_hash(Plan *lefttree) +make_hash(Plan *lefttree, + Oid skewTable, + AttrNumber skewColumn, + Oid skewColType, + int32 skewColTypmod) { Hash *node = makeNode(Hash); Plan *plan = &node->plan; @@ -2730,6 +2779,11 @@ make_hash(Plan *lefttree) plan->lefttree = lefttree; plan->righttree = NULL; + node->skewTable = skewTable; + node->skewColumn = skewColumn; + node->skewColType = skewColType; + node->skewColTypmod = skewColTypmod; + return node; } |