diff options
Diffstat (limited to 'src/backend/optimizer/plan/planmain.c')
| -rw-r--r-- | src/backend/optimizer/plan/planmain.c | 73 |
1 files changed, 14 insertions, 59 deletions
diff --git a/src/backend/optimizer/plan/planmain.c b/src/backend/optimizer/plan/planmain.c index f6f62abfe08..802e5970416 100644 --- a/src/backend/optimizer/plan/planmain.c +++ b/src/backend/optimizer/plan/planmain.c @@ -7,7 +7,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planmain.c,v 1.41 1999/08/21 03:49:03 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planmain.c,v 1.42 1999/08/22 20:14:48 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -27,7 +27,6 @@ static Plan *subplanner(Query *root, List *flat_tlist, List *qual); -static Result *make_result(List *tlist, Node *resconstantqual, Plan *subplan); /* * query_planner @@ -84,11 +83,6 @@ query_planner(Query *root, * topmost result node. */ qual = pull_constant_clauses(qual, &constant_qual); - /* - * The opids for the variable qualifications will be fixed later, but - * someone seems to think that the constant quals need to be fixed here. - */ - fix_opids(constant_qual); /* * Create a target list that consists solely of (resdom var) target @@ -124,8 +118,7 @@ query_planner(Query *root, { SeqScan *scan = make_seqscan(tlist, NIL, - root->resultRelation, - (Plan *) NULL); + root->resultRelation); if (constant_qual != NULL) return ((Plan *) make_result(tlist, @@ -141,14 +134,10 @@ query_planner(Query *root, } /* - * Find the subplan (access path) and destructively modify the target - * list of the newly created subplan to contain the appropriate join - * references. + * Choose the best access path and build a plan for it. */ subplan = subplanner(root, level_tlist, qual); - set_tlist_references(subplan); - /* * Build a result node linking the plan if we have constant quals */ @@ -158,33 +147,24 @@ query_planner(Query *root, (Node *) constant_qual, subplan); - /* - * Fix all varno's of the Result's node target list. - */ - set_tlist_references(subplan); - root->query_pathkeys = NIL; /* result is unordered, no? */ return subplan; } /* - * fix up the flattened target list of the plan root node so that - * expressions are evaluated. this forces expression evaluations that - * may involve expensive function calls to be delayed to the very last - * stage of query execution. this could be bad. but it is joey's - * responsibility to optimally push these expressions down the plan - * tree. -- Wei + * Replace the toplevel plan node's flattened target list with the + * targetlist given by my caller, so that expressions are evaluated. * - * Note: formerly there was a test here to skip the unflatten call if - * we expected union_planner to insert a Group or Agg node above our - * result. However, now union_planner tells us exactly what it wants - * returned, and we just do it. Much cleaner. + * This implies that all expression evaluations are done at the root + * of the plan tree. Once upon a time there was code to try to push + * expensive function calls down to lower plan nodes, but that's dead + * code and has been for a long time... */ else { - subplan->targetlist = unflatten_tlist(tlist, - subplan->targetlist); + subplan->targetlist = tlist; + return subplan; } @@ -330,36 +310,11 @@ subplanner(Query *root, /* Nothing for it but to sort the cheapestpath... * - * we indicate we failed to sort the plan, and let the caller - * stick the appropriate sortplan on top. + * We indicate we failed to sort the plan, and let the caller + * stick the appropriate sort node on top. union_planner has to be + * able to add a sort node anyway, so no need for extra code here. */ root->query_pathkeys = NIL; /* sorry, it ain't sorted */ return create_plan(final_rel->cheapestpath); } - -/***************************************************************************** - * - *****************************************************************************/ - -static Result * -make_result(List *tlist, - Node *resconstantqual, - Plan *subplan) -{ - Result *node = makeNode(Result); - Plan *plan = &node->plan; - -#ifdef NOT_USED - tlist = generate_fjoin(tlist); -#endif - plan->cost = (subplan ? subplan->cost : 0); - plan->state = (EState *) NULL; - plan->targetlist = tlist; - plan->lefttree = subplan; - plan->righttree = NULL; - node->resconstantqual = resconstantqual; - node->resstate = NULL; - - return node; -} |