diff options
Diffstat (limited to 'src/backend/utils/adt/selfuncs.c')
| -rw-r--r-- | src/backend/utils/adt/selfuncs.c | 28 |
1 files changed, 22 insertions, 6 deletions
diff --git a/src/backend/utils/adt/selfuncs.c b/src/backend/utils/adt/selfuncs.c index 1c3bba0ca2d..93e8040b9b5 100644 --- a/src/backend/utils/adt/selfuncs.c +++ b/src/backend/utils/adt/selfuncs.c @@ -15,7 +15,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/utils/adt/selfuncs.c,v 1.152 2003/12/29 22:22:45 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/utils/adt/selfuncs.c,v 1.153 2004/01/05 23:39:54 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -94,6 +94,7 @@ #include "optimizer/paths.h" #include "optimizer/plancat.h" #include "optimizer/prep.h" +#include "optimizer/restrictinfo.h" #include "optimizer/tlist.h" #include "optimizer/var.h" #include "parser/parse_expr.h" @@ -3896,13 +3897,13 @@ genericcostestimate(Query *root, RelOptInfo *rel, double numIndexTuples; double numIndexPages; QualCost index_qual_cost; - List *selectivityQuals = indexQuals; + List *selectivityQuals; /* * If the index is partial, AND the index predicate with the * explicitly given indexquals to produce a more accurate idea of the - * index selectivity. This may produce redundant clauses. We can get - * rid of exact duplicates by using set_union(). We expect that most + * index selectivity. This may produce redundant clauses. We get rid + * of exact duplicates in the code below. We expect that most * cases of partial redundancy (such as "x < 4" from the qual and * "x < 5" from the predicate) will be recognized and handled correctly * by clauselist_selectivity(). This assumption is somewhat fragile, @@ -3913,10 +3914,25 @@ genericcostestimate(Query *root, RelOptInfo *rel, * necessarily a bad thing. But it'd be nice to do better someday. * * Note that index->indpred and indexQuals are both in implicit-AND form, - * so ANDing them together just takes merging the lists. + * so ANDing them together just takes merging the lists. However, + * eliminating duplicates is a bit trickier because indexQuals contains + * RestrictInfo nodes and the indpred does not. It is okay to pass a + * mixed list to clauselist_selectivity, but we have to work a bit to + * generate a list without logical duplicates. (We could just set_union + * indpred and strippedQuals, but then we'd not get caching of per-qual + * selectivity estimates.) */ if (index->indpred != NIL) - selectivityQuals = set_union(index->indpred, indexQuals); + { + List *strippedQuals; + List *predExtraQuals; + + strippedQuals = get_actual_clauses(indexQuals); + predExtraQuals = set_difference(index->indpred, strippedQuals); + selectivityQuals = nconc(predExtraQuals, indexQuals); + } + else + selectivityQuals = indexQuals; /* Estimate the fraction of main-table tuples that will be visited */ *indexSelectivity = clauselist_selectivity(root, selectivityQuals, |