diff options
Diffstat (limited to 'src/backend/optimizer/path/allpaths.c')
| -rw-r--r-- | src/backend/optimizer/path/allpaths.c | 76 |
1 files changed, 37 insertions, 39 deletions
diff --git a/src/backend/optimizer/path/allpaths.c b/src/backend/optimizer/path/allpaths.c index ebc303d4654..15f29847d31 100644 --- a/src/backend/optimizer/path/allpaths.c +++ b/src/backend/optimizer/path/allpaths.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/optimizer/path/allpaths.c,v 1.79 2001/10/18 16:11:41 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/optimizer/path/allpaths.c,v 1.80 2001/10/25 05:49:32 momjian Exp $ * *------------------------------------------------------------------------- */ @@ -38,10 +38,10 @@ static void set_base_rel_pathlists(Query *root); static void set_plain_rel_pathlist(Query *root, RelOptInfo *rel, RangeTblEntry *rte); static void set_inherited_rel_pathlist(Query *root, RelOptInfo *rel, - Index rti, RangeTblEntry *rte, - List *inheritlist); + Index rti, RangeTblEntry *rte, + List *inheritlist); static void set_subquery_pathlist(Query *root, RelOptInfo *rel, - Index rti, RangeTblEntry *rte); + Index rti, RangeTblEntry *rte); static RelOptInfo *make_one_rel_by_joins(Query *root, int levels_needed, List *initial_rels); @@ -160,7 +160,7 @@ set_plain_rel_pathlist(Query *root, RelOptInfo *rel, RangeTblEntry *rte) * Build access paths for a inheritance tree rooted at rel * * inheritlist is a list of RT indexes of all tables in the inheritance tree, - * including a duplicate of the parent itself. Note we will not come here + * including a duplicate of the parent itself. Note we will not come here * unless there's at least one child in addition to the parent. * * NOTE: the passed-in rel and RTE will henceforth represent the appended @@ -192,9 +192,9 @@ set_inherited_rel_pathlist(Query *root, RelOptInfo *rel, elog(ERROR, "SELECT FOR UPDATE is not supported for inherit queries"); /* - * The executor will check the parent table's access permissions when it - * examines the parent's inheritlist entry. There's no need to check - * twice, so turn off access check bits in the original RTE. + * The executor will check the parent table's access permissions when + * it examines the parent's inheritlist entry. There's no need to + * check twice, so turn off access check bits in the original RTE. */ rte->checkForRead = false; rte->checkForWrite = false; @@ -230,8 +230,8 @@ set_inherited_rel_pathlist(Query *root, RelOptInfo *rel, /* * Copy the parent's targetlist and restriction quals to the * child, with attribute-number adjustment as needed. We don't - * bother to copy the join quals, since we can't do any joining - * of the individual tables. + * bother to copy the join quals, since we can't do any joining of + * the individual tables. */ childrel->targetlist = (List *) adjust_inherited_attrs((Node *) rel->targetlist, @@ -282,32 +282,32 @@ set_subquery_pathlist(Query *root, RelOptInfo *rel, /* * If there are any restriction clauses that have been attached to the - * subquery relation, consider pushing them down to become HAVING quals - * of the subquery itself. (Not WHERE clauses, since they may refer to - * subquery outputs that are aggregate results. But planner.c will - * transfer them into the subquery's WHERE if they do not.) This - * transformation is useful because it may allow us to generate a better - * plan for the subquery than evaluating all the subquery output rows - * and then filtering them. + * subquery relation, consider pushing them down to become HAVING + * quals of the subquery itself. (Not WHERE clauses, since they may + * refer to subquery outputs that are aggregate results. But + * planner.c will transfer them into the subquery's WHERE if they do + * not.) This transformation is useful because it may allow us to + * generate a better plan for the subquery than evaluating all the + * subquery output rows and then filtering them. * * There are several cases where we cannot push down clauses: * * 1. If the subquery contains set ops (UNION/INTERSECT/EXCEPT) we do not - * push down any qual clauses, since the planner doesn't support quals at - * the top level of a setop. (With suitable analysis we could try to push - * the quals down into the component queries of the setop, but getting it - * right seems nontrivial. Work on this later.) + * push down any qual clauses, since the planner doesn't support quals + * at the top level of a setop. (With suitable analysis we could try + * to push the quals down into the component queries of the setop, but + * getting it right seems nontrivial. Work on this later.) * * 2. If the subquery has a LIMIT clause or a DISTINCT ON clause, we must * not push down any quals, since that could change the set of rows * returned. (Actually, we could push down quals into a DISTINCT ON - * subquery if they refer only to DISTINCT-ed output columns, but checking - * that seems more work than it's worth. In any case, a plain DISTINCT is - * safe to push down past.) + * subquery if they refer only to DISTINCT-ed output columns, but + * checking that seems more work than it's worth. In any case, a + * plain DISTINCT is safe to push down past.) * * 3. We do not push down clauses that contain subselects, mainly because - * I'm not sure it will work correctly (the subplan hasn't yet transformed - * sublinks to subselects). + * I'm not sure it will work correctly (the subplan hasn't yet + * transformed sublinks to subselects). * * Non-pushed-down clauses will get evaluated as qpquals of the * SubqueryScan node. @@ -337,22 +337,23 @@ set_subquery_pathlist(Query *root, RelOptInfo *rel, else { /* - * We need to replace Vars in the clause (which must refer to - * outputs of the subquery) with copies of the subquery's - * targetlist expressions. Note that at this point, any - * uplevel Vars in the clause should have been replaced with - * Params, so they need no work. + * We need to replace Vars in the clause (which must refer + * to outputs of the subquery) with copies of the + * subquery's targetlist expressions. Note that at this + * point, any uplevel Vars in the clause should have been + * replaced with Params, so they need no work. */ clause = ResolveNew(clause, rti, 0, subquery->targetList, CMD_SELECT, 0); subquery->havingQual = make_and_qual(subquery->havingQual, clause); + /* * We need not change the subquery's hasAggs or - * hasSublinks flags, since we can't be pushing - * down any aggregates that weren't there before, - * and we don't push down subselects at all. + * hasSublinks flags, since we can't be pushing down any + * aggregates that weren't there before, and we don't push + * down subselects at all. */ } } @@ -412,7 +413,6 @@ make_fromexpr_rel(Query *root, FromExpr *from) if (levels_needed == 1) { - /* * Single jointree node, so we're done. */ @@ -420,7 +420,6 @@ make_fromexpr_rel(Query *root, FromExpr *from) } else { - /* * Consider the different orders in which we could join the rels, * using either GEQO or regular optimizer. @@ -552,7 +551,7 @@ print_restrictclauses(Query *root, List *clauses) static void print_path(Query *root, Path *path, int indent) { - const char *ptype; + const char *ptype; bool join; int i; @@ -650,7 +649,7 @@ debug_print_rel(Query *root, RelOptInfo *rel) foreach(l, rel->joininfo) { - JoinInfo *j = (JoinInfo *) lfirst(l); + JoinInfo *j = (JoinInfo *) lfirst(l); printf("\tjoininfo ("); print_relids(j->unjoined_relids); @@ -669,5 +668,4 @@ debug_print_rel(Query *root, RelOptInfo *rel) printf("\n"); fflush(stdout); } - #endif /* OPTIMIZER_DEBUG */ |