diff options
Diffstat (limited to 'src/backend/optimizer/path/orindxpath.c')
| -rw-r--r-- | src/backend/optimizer/path/orindxpath.c | 51 |
1 files changed, 26 insertions, 25 deletions
diff --git a/src/backend/optimizer/path/orindxpath.c b/src/backend/optimizer/path/orindxpath.c index 7661f812435..c2de25aa4c6 100644 --- a/src/backend/optimizer/path/orindxpath.c +++ b/src/backend/optimizer/path/orindxpath.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/optimizer/path/orindxpath.c,v 1.61 2004/08/29 04:12:33 momjian Exp $ + * $PostgreSQL: pgsql/src/backend/optimizer/path/orindxpath.c,v 1.62 2004/08/29 05:06:43 momjian Exp $ * *------------------------------------------------------------------------- */ @@ -23,7 +23,7 @@ static IndexPath *best_or_subclause_indexes(Query *root, RelOptInfo *rel, - List *subclauses); + List *subclauses); static bool best_or_subclause_index(Query *root, RelOptInfo *rel, Expr *subclause, @@ -55,7 +55,7 @@ static bool best_or_subclause_index(Query *root, * * The added quals are partially redundant with the original OR, and therefore * will cause the size of the joinrel to be underestimated when it is finally - * formed. (This would be true of a full transformation to CNF as well; the + * formed. (This would be true of a full transformation to CNF as well; the * fault is not really in the transformation, but in clauselist_selectivity's * inability to recognize redundant conditions.) To minimize the collateral * damage, we want to minimize the number of quals added. Therefore we do @@ -70,7 +70,7 @@ static bool best_or_subclause_index(Query *root, * it is finally formed. This is a MAJOR HACK: it depends on the fact * that clause selectivities are cached and on the fact that the same * RestrictInfo node will appear in every joininfo list that might be used - * when the joinrel is formed. And it probably isn't right in cases where + * when the joinrel is formed. And it probably isn't right in cases where * the size estimation is nonlinear (i.e., outer and IN joins). But it * beats not doing anything. * @@ -103,9 +103,9 @@ create_or_index_quals(Query *root, RelOptInfo *rel) ListCell *i; /* - * We use the best_or_subclause_indexes() machinery to locate the - * best combination of restriction subclauses. Note we must ignore - * any joinclauses that are not marked valid_everywhere, because they + * We use the best_or_subclause_indexes() machinery to locate the best + * combination of restriction subclauses. Note we must ignore any + * joinclauses that are not marked valid_everywhere, because they * cannot be pushed down due to outer-join rules. */ foreach(i, rel->joininfo) @@ -124,12 +124,12 @@ create_or_index_quals(Query *root, RelOptInfo *rel) pathnode = best_or_subclause_indexes(root, rel, - ((BoolExpr *) rinfo->orclause)->args); + ((BoolExpr *) rinfo->orclause)->args); if (pathnode) { if (bestpath == NULL || - pathnode->path.total_cost < bestpath->path.total_cost) + pathnode->path.total_cost < bestpath->path.total_cost) { bestpath = pathnode; bestrinfo = rinfo; @@ -144,8 +144,8 @@ create_or_index_quals(Query *root, RelOptInfo *rel) return false; /* - * Convert the indexclauses structure to a RestrictInfo tree, - * and add it to the rel's restriction list. + * Convert the indexclauses structure to a RestrictInfo tree, and add + * it to the rel's restriction list. */ newrinfos = make_restrictinfo_from_indexclauses(bestpath->indexclauses, true, true); @@ -157,9 +157,9 @@ create_or_index_quals(Query *root, RelOptInfo *rel) * Adjust the original OR clause's cached selectivity to compensate * for the selectivity of the added (but redundant) lower-level qual. * This should result in the join rel getting approximately the same - * rows estimate as it would have gotten without all these shenanigans. - * (XXX major hack alert ... this depends on the assumption that the - * selectivity will stay cached ...) + * rows estimate as it would have gotten without all these + * shenanigans. (XXX major hack alert ... this depends on the + * assumption that the selectivity will stay cached ...) */ or_selec = clause_selectivity(root, (Node *) or_rinfo, 0, JOIN_INNER); @@ -193,8 +193,8 @@ create_or_index_paths(Query *root, RelOptInfo *rel) ListCell *l; /* - * Check each restriction clause to see if it is an OR clause, and if so, - * try to make a path using it. + * Check each restriction clause to see if it is an OR clause, and if + * so, try to make a path using it. */ foreach(l, rel->baserestrictinfo) { @@ -206,7 +206,7 @@ create_or_index_paths(Query *root, RelOptInfo *rel) pathnode = best_or_subclause_indexes(root, rel, - ((BoolExpr *) rinfo->orclause)->args); + ((BoolExpr *) rinfo->orclause)->args); if (pathnode) add_path(rel, (Path *) pathnode); @@ -264,20 +264,21 @@ best_or_subclause_indexes(Query *root, if (!best_or_subclause_index(root, rel, subclause, &best_indexinfo, &best_indexclauses, &best_indexquals, - &best_startup_cost, &best_total_cost)) + &best_startup_cost, &best_total_cost)) return NULL; /* failed to match this subclause */ infos = lappend(infos, best_indexinfo); clauses = lappend(clauses, best_indexclauses); quals = lappend(quals, best_indexquals); + /* - * Path startup_cost is the startup cost for the first index scan only; - * startup costs for later scans will be paid later on, so they just - * get reflected in total_cost. + * Path startup_cost is the startup cost for the first index scan + * only; startup costs for later scans will be paid later on, so + * they just get reflected in total_cost. * * Total cost is sum of the per-scan costs. */ - if (slist == list_head(subclauses)) /* first scan? */ + if (slist == list_head(subclauses)) /* first scan? */ path_startup_cost = best_startup_cost; path_total_cost += best_total_cost; } @@ -292,8 +293,8 @@ best_or_subclause_indexes(Query *root, /* * This is an IndexScan, but the overall result will consist of tuples - * extracted in multiple passes (one for each subclause of the OR), - * so the result cannot be claimed to have any particular ordering. + * extracted in multiple passes (one for each subclause of the OR), so + * the result cannot be claimed to have any particular ordering. */ pathnode->path.pathkeys = NIL; @@ -339,7 +340,7 @@ best_or_subclause_index(Query *root, RelOptInfo *rel, Expr *subclause, IndexOptInfo **retIndexInfo, /* return value */ - List **retIndexClauses, /* return value */ + List **retIndexClauses, /* return value */ List **retIndexQuals, /* return value */ Cost *retStartupCost, /* return value */ Cost *retTotalCost) /* return value */ |