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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2000-02-16 00:59:27 +0000 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2000-02-16 00:59:27 +0000 |
| commit | deee4e1612b5d74e81f50d20ccf5c96628b00487 (patch) | |
| tree | 68085746cc2c0eceb66881beea382d4e5481276b /src/backend/utils/adt/selfuncs.c | |
| parent | 9c80cceb023130ac94f1167ce8ab9355de1a9bd0 (diff) | |
| download | postgresql-deee4e1612b5d74e81f50d20ccf5c96628b00487.tar.gz postgresql-deee4e1612b5d74e81f50d20ccf5c96628b00487.zip | |
Make eqsel produce better results for boolean columns,
and make scalarltsel a little more forgiving at the boundaries of the
known range of a column value.
Diffstat (limited to 'src/backend/utils/adt/selfuncs.c')
| -rw-r--r-- | src/backend/utils/adt/selfuncs.c | 21 |
1 files changed, 12 insertions, 9 deletions
diff --git a/src/backend/utils/adt/selfuncs.c b/src/backend/utils/adt/selfuncs.c index 30106744ded..6b1f5cde26f 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 1.55 2000/02/15 20:49:21 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/utils/adt/selfuncs.c,v 1.56 2000/02/16 00:59:27 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -144,10 +144,13 @@ eqsel(Oid opid, selec = 1.0 - commonfrac - nullfrac; if (selec > commonfrac) selec = commonfrac; - /* and in fact it's probably less, so apply a fudge - * factor. + /* and in fact it's probably less, so we should apply + * a fudge factor. The only case where we don't is + * for a boolean column, where indeed we have estimated + * the less-common value's frequency exactly! */ - selec *= 0.5; + if (typid != BOOLOID) + selec *= 0.5; } } else @@ -310,20 +313,20 @@ scalarltsel(Oid opid, /* If we trusted the stats fully, we could return a small or * large selec depending on which side of the single data point * the constant is on. But it seems better to assume that the - * stats are out of date and return a default... + * stats are wrong and return a default... */ *result = DEFAULT_INEQ_SEL; - } - else if (val <= low || val >= high) + } + else if (val < low || val > high) { /* If given value is outside the statistical range, return a * small or large value; but not 0.0/1.0 since there is a chance * the stats are out of date. */ if (flag & SEL_RIGHT) - *result = (val <= low) ? 0.01 : 0.99; + *result = (val < low) ? 0.001 : 0.999; else - *result = (val <= low) ? 0.99 : 0.01; + *result = (val < low) ? 0.999 : 0.001; } else { |