diff options
Diffstat (limited to 'src/backend/utils/adt/selfuncs.c')
| -rw-r--r-- | src/backend/utils/adt/selfuncs.c | 36 |
1 files changed, 26 insertions, 10 deletions
diff --git a/src/backend/utils/adt/selfuncs.c b/src/backend/utils/adt/selfuncs.c index 211ccbf87bd..b4216b165d8 100644 --- a/src/backend/utils/adt/selfuncs.c +++ b/src/backend/utils/adt/selfuncs.c @@ -15,7 +15,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/utils/adt/selfuncs.c,v 1.119 2002/10/19 02:56:16 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/utils/adt/selfuncs.c,v 1.119.2.1 2003/01/22 20:17:07 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -1740,7 +1740,9 @@ mergejoinscansel(Query *root, Node *clause, rsortop, ltop, gtop, - revltop; + leop, + revgtop, + revleop; Datum leftmax, rightmax; double selec; @@ -1779,35 +1781,49 @@ mergejoinscansel(Query *root, Node *clause, /* Look up the "left < right" and "left > right" operators */ op_mergejoin_crossops(opno, <op, >op, NULL, NULL); - /* Look up the "right < left" operator */ - revltop = get_commutator(gtop); - if (!OidIsValid(revltop)) - return; /* shouldn't happen */ + /* Look up the "left <= right" operator */ + leop = get_negator(gtop); + if (!OidIsValid(leop)) + return; /* insufficient info in catalogs */ + + /* Look up the "right > left" operator */ + revgtop = get_commutator(ltop); + if (!OidIsValid(revgtop)) + return; /* insufficient info in catalogs */ + + /* Look up the "right <= left" operator */ + revleop = get_negator(revgtop); + if (!OidIsValid(revleop)) + return; /* insufficient info in catalogs */ /* * 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. */ - selec = scalarineqsel(root, ltop, false, left, + selec = scalarineqsel(root, leop, false, left, rightmax, right->vartype); if (selec != DEFAULT_INEQ_SEL) *leftscan = selec; /* And similarly for the right variable. */ - selec = scalarineqsel(root, revltop, false, right, + selec = scalarineqsel(root, revleop, false, right, leftmax, left->vartype); if (selec != DEFAULT_INEQ_SEL) *rightscan = selec; /* * Only one of the two fractions can really be less than 1.0; believe - * the smaller estimate and reset the other one to exactly 1.0. + * the smaller estimate and reset the other one to exactly 1.0. If we + * get exactly equal estimates (as can easily happen with self-joins), + * believe neither. */ if (*leftscan > *rightscan) *leftscan = 1.0; - else + else if (*leftscan < *rightscan) *rightscan = 1.0; + else + *leftscan = *rightscan = 1.0; } /* |