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author | Tom Lane <tgl@sss.pgh.pa.us> | 2006-05-18 19:56:46 +0000 |
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committer | Tom Lane <tgl@sss.pgh.pa.us> | 2006-05-18 19:56:46 +0000 |
commit | eed57b1b9259ee7cf95c022b39cddde3ee4604a9 (patch) | |
tree | 8168977e07b352ea2f57ac2dda6cd9d4a360d8cb /src | |
parent | f32325264273e5d101064a7133aa5a3d90b0ad34 (diff) | |
download | postgresql-eed57b1b9259ee7cf95c022b39cddde3ee4604a9.tar.gz postgresql-eed57b1b9259ee7cf95c022b39cddde3ee4604a9.zip |
Fix choose_bitmap_and() so that partial index predicates are considered when
deciding whether a potential additional indexscan is redundant or not. As now
coded, any use of a partial index that was already used in a previous AND arm
will be rejected as redundant. This might be overly restrictive, but not
considering the point at all is definitely bad, as per example in bug #2441
from Arjen van der Meijden. In particular, a clauseless scan of a partial
index was *never* considered redundant by the previous coding, and that's
surely wrong. Being more flexible would also require some consideration
of how not to double-count the index predicate's selectivity.
Diffstat (limited to 'src')
-rw-r--r-- | src/backend/optimizer/path/indxpath.c | 19 |
1 files changed, 10 insertions, 9 deletions
diff --git a/src/backend/optimizer/path/indxpath.c b/src/backend/optimizer/path/indxpath.c index 935494e0778..ac6de3d82a5 100644 --- a/src/backend/optimizer/path/indxpath.c +++ b/src/backend/optimizer/path/indxpath.c @@ -9,7 +9,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/optimizer/path/indxpath.c,v 1.205 2006/05/18 17:12:10 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/optimizer/path/indxpath.c,v 1.206 2006/05/18 19:56:46 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -616,10 +616,10 @@ choose_bitmap_and(PlannerInfo *root, RelOptInfo *rel, List *paths) * non-selective. In any case, we'd surely be drastically misestimating * the selectivity if we count the same condition twice. * - * XXX is there any risk of throwing away a useful partial index here - * because we don't explicitly look at indpred? At least in simple cases, - * the partial index will sort before competing non-partial indexes and so - * it makes the right choice, but perhaps we need to work harder. + * We include index predicate conditions in the redundancy test. Because + * the test is just for pointer equality and not equal(), the effect is + * that use of the same partial index in two different AND elements is + * considered redundant. (XXX is this too strong?) * * Note: outputting the selected sub-paths in selectivity order is a good * thing even if we weren't using that as part of the selection method, @@ -732,14 +732,14 @@ bitmap_and_cost_est(PlannerInfo *root, RelOptInfo *rel, List *paths) /* * pull_indexpath_quals * - * Given the Path structure for a plain or bitmap indexscan, extract a - * list of RestrictInfo nodes for all the indexquals used in the Path. + * Given the Path structure for a plain or bitmap indexscan, extract a list + * of all the indexquals and index predicate conditions used in the Path. * * This is sort of a simplified version of make_restrictinfo_from_bitmapqual; * here, we are not trying to produce an accurate representation of the AND/OR * semantics of the Path, but just find out all the base conditions used. * - * The result list contains pointers to the RestrictInfos used in the Path, + * The result list contains pointers to the expressions used in the Path, * but all the list cells are freshly built, so it's safe to destructively * modify the list (eg, by concat'ing it with other lists). */ @@ -777,7 +777,8 @@ pull_indexpath_quals(Path *bitmapqual) { IndexPath *ipath = (IndexPath *) bitmapqual; - result = list_copy(ipath->indexclauses); + result = get_actual_clauses(ipath->indexclauses); + result = list_concat(result, list_copy(ipath->indexinfo->indpred)); } else elog(ERROR, "unrecognized node type: %d", nodeTag(bitmapqual)); |