diff options
Diffstat (limited to 'src/backend/optimizer/prep/prepunion.c')
| -rw-r--r-- | src/backend/optimizer/prep/prepunion.c | 49 |
1 files changed, 38 insertions, 11 deletions
diff --git a/src/backend/optimizer/prep/prepunion.c b/src/backend/optimizer/prep/prepunion.c index 9a86cb2348..10a48c666e 100644 --- a/src/backend/optimizer/prep/prepunion.c +++ b/src/backend/optimizer/prep/prepunion.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/optimizer/prep/prepunion.c,v 1.44 2000/02/15 03:37:26 thomas Exp $ + * $Header: /cvsroot/pgsql/src/backend/optimizer/prep/prepunion.c,v 1.45 2000/02/15 20:49:19 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -122,28 +122,35 @@ plan_union_queries(Query *parse) /* Is this a simple one */ if (!union_all_found || !union_found || - /* A trailing UNION negates the affect of earlier UNION ALLs */ + /* A trailing UNION negates the effect of earlier UNION ALLs */ !last_union_all_flag) { List *hold_unionClause = parse->unionClause; + double tuple_fraction = -1.0; /* default processing */ - /* we will do this later, so don't do it now */ + /* we will do sorting later, so don't do it now */ if (!union_all_found || !last_union_all_flag) { parse->sortClause = NIL; parse->distinctClause = NIL; + /* + * force lower-level planning to assume that all tuples will + * be retrieved, even if it sees a LIMIT in the query node. + */ + tuple_fraction = 0.0; } parse->unionClause = NIL; /* prevent recursion */ - union_plans = lcons(union_planner(parse), NIL); + union_plans = lcons(union_planner(parse, tuple_fraction), NIL); union_rts = lcons(parse->rtable, NIL); foreach(ulist, hold_unionClause) { Query *union_query = lfirst(ulist); - union_plans = lappend(union_plans, union_planner(union_query)); + union_plans = lappend(union_plans, + union_planner(union_query, tuple_fraction)); union_rts = lappend(union_rts, union_query->rtable); } } @@ -165,9 +172,12 @@ plan_union_queries(Query *parse) /* * Recursion, but UNION only. The last one is a UNION, so it will - * not come here in recursion, + * not come here in recursion. + * + * XXX is it OK to pass default -1 to union_planner in this path, + * or should we force a tuple_fraction value? */ - union_plans = lcons(union_planner(parse), NIL); + union_plans = lcons(union_planner(parse, -1.0), NIL); union_rts = lcons(parse->rtable, NIL); /* Append the remaining UNION ALLs */ @@ -175,7 +185,8 @@ plan_union_queries(Query *parse) { Query *union_all_query = lfirst(ulist); - union_plans = lappend(union_plans, union_planner(union_all_query)); + union_plans = lappend(union_plans, + union_planner(union_all_query, -1.0)); union_rts = lappend(union_rts, union_all_query->rtable); } } @@ -295,6 +306,7 @@ plan_inherit_query(Relids relids, List *union_plans = NIL; List *union_rtentries = NIL; List *save_tlist = root->targetList; + double tuple_fraction; List *i; /* @@ -303,6 +315,17 @@ plan_inherit_query(Relids relids, */ root->targetList = NIL; + /* + * If we are going to need sorting or grouping at the top level, + * force lower-level planners to assume that all tuples will be + * retrieved. + */ + if (root->distinctClause || root->sortClause || + root->groupClause || root->hasAggs) + tuple_fraction = 0.0; /* will need all tuples from each subplan */ + else + tuple_fraction = -1.0; /* default behavior is OK (I think) */ + foreach(i, relids) { int relid = lfirsti(i); @@ -344,7 +367,8 @@ plan_inherit_query(Relids relids, relid, new_root); - union_plans = lappend(union_plans, union_planner(new_root)); + union_plans = lappend(union_plans, + union_planner(new_root, tuple_fraction)); union_rtentries = lappend(union_rtentries, new_rt_entry); } @@ -551,14 +575,17 @@ make_append(List *appendplans, node->unionrtables = unionrtables; node->inheritrelid = rt_index; node->inheritrtable = inheritrtable; - node->plan.cost = 0; + node->plan.startup_cost = 0; + node->plan.total_cost = 0; node->plan.plan_rows = 0; node->plan.plan_width = 0; foreach(subnode, appendplans) { Plan *subplan = (Plan *) lfirst(subnode); - node->plan.cost += subplan->cost; + if (subnode == appendplans) /* first node? */ + node->plan.startup_cost = subplan->startup_cost; + node->plan.total_cost += subplan->total_cost; node->plan.plan_rows += subplan->plan_rows; if (node->plan.plan_width < subplan->plan_width) node->plan.plan_width = subplan->plan_width; |