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Commitb71761d

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Reduce eqsel()'s fudge-factor for estimating the frequency of values
other than the most common value in a column. We had had 0.5, make it0.1 to make it more likely that an indexscan will be chosen. Reallyneed better statistics instead, but this should stem the bleedingmeanwhile ...
1 parentbe6e771 commitb71761d

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1 file changed

+6
-3
lines changed

1 file changed

+6
-3
lines changed

‎src/backend/utils/adt/selfuncs.c‎

Lines changed: 6 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -15,7 +15,7 @@
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/utils/adt/selfuncs.c,v 1.65 2000/04/16 04:41:02 tgl Exp $
18+
* $Header: /cvsroot/pgsql/src/backend/utils/adt/selfuncs.c,v 1.66 2000/05/26 17:19:15 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
@@ -55,6 +55,9 @@
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/* default selectivity estimate for pattern-match operators such as LIKE */
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#defineDEFAULT_MATCH_SEL0.01
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58+
/* "fudge factor" for estimating frequency of not-most-common values */
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#defineNOT_MOST_COMMON_RATIO 0.1
60+
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staticboolconvert_to_scalar(Datumvalue,Oidvaluetypid,double*scaledvalue,
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Datumlobound,Datumhibound,Oidboundstypid,
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double*scaledlobound,double*scaledhibound);
@@ -190,7 +193,7 @@ eqsel(Oid opid,
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* exactly!
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*/
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if (typid!=BOOLOID)
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selec *=0.5;
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selec *=NOT_MOST_COMMON_RATIO;
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}
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}
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else
@@ -209,7 +212,7 @@ eqsel(Oid opid,
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* and in fact it's probably less, so apply a fudge
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* factor.
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*/
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selec *=0.5;
215+
selec *=NOT_MOST_COMMON_RATIO;
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}
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/* result should be in range, but make sure... */

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