diff options
Diffstat (limited to 'src/backend/utils/adt/selfuncs.c')
| -rw-r--r-- | src/backend/utils/adt/selfuncs.c | 31 |
1 files changed, 26 insertions, 5 deletions
diff --git a/src/backend/utils/adt/selfuncs.c b/src/backend/utils/adt/selfuncs.c index 493df17b6c2..85e66a3b1c4 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 1.220 2007/01/20 20:45:40 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/utils/adt/selfuncs.c,v 1.221 2007/01/22 20:00:40 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -2112,8 +2112,8 @@ icnlikejoinsel(PG_FUNCTION_ARGS) * we can estimate how much of the input will actually be read. This * can have a considerable impact on the cost when using indexscans. * - * clause should be a clause already known to be mergejoinable. opfamily and - * strategy specify the sort ordering being used. + * clause should be a clause already known to be mergejoinable. opfamily, + * strategy, and nulls_first specify the sort ordering being used. * * *leftscan is set to the fraction of the left-hand variable expected * to be scanned (0 to 1), and similarly *rightscan for the right-hand @@ -2121,7 +2121,7 @@ icnlikejoinsel(PG_FUNCTION_ARGS) */ void mergejoinscansel(PlannerInfo *root, Node *clause, - Oid opfamily, int strategy, + Oid opfamily, int strategy, bool nulls_first, Selectivity *leftscan, Selectivity *rightscan) { @@ -2214,18 +2214,39 @@ mergejoinscansel(PlannerInfo *root, Node *clause, /* * Now, the fraction of the left variable that will be scanned is the * fraction that's <= the right-side maximum value. But only believe - * non-default estimates, else stick with our 1.0. + * non-default estimates, else stick with our 1.0. Also, if the sort + * order is nulls-first, we're going to have to read over any nulls too. */ selec = scalarineqsel(root, leop, false, &leftvar, rightmax, op_righttype); if (selec != DEFAULT_INEQ_SEL) + { + if (nulls_first && HeapTupleIsValid(leftvar.statsTuple)) + { + Form_pg_statistic stats; + + stats = (Form_pg_statistic) GETSTRUCT(leftvar.statsTuple); + selec += stats->stanullfrac; + CLAMP_PROBABILITY(selec); + } *leftscan = selec; + } /* And similarly for the right variable. */ selec = scalarineqsel(root, revleop, false, &rightvar, leftmax, op_lefttype); if (selec != DEFAULT_INEQ_SEL) + { + if (nulls_first && HeapTupleIsValid(rightvar.statsTuple)) + { + Form_pg_statistic stats; + + stats = (Form_pg_statistic) GETSTRUCT(rightvar.statsTuple); + selec += stats->stanullfrac; + CLAMP_PROBABILITY(selec); + } *rightscan = selec; + } /* * Only one of the two fractions can really be less than 1.0; believe the |