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Clarify a confusing comment about MCVs vs histogram entries.

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Per Nathan Boley.
This commit is contained in:
Tom Lane 2009-01-06 23:46:06 +00:00
parent 17f601ecb2
commit 82c9662378
1 changed files with 4 additions and 2 deletions
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6
src/backend/commands/analyze.c
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@ -8,7 +8,7 @@
* *
* *
* IDENTIFICATION * IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/commands/analyze.c,v 1.131 2009/01/01 17:23:37 momjian Exp $ * $PostgreSQL: pgsql/src/backend/commands/analyze.c,v 1.132 2009/01/06 23:46:06 tgl Exp $
* *
*------------------------------------------------------------------------- *-------------------------------------------------------------------------
*/ */
@ -2149,7 +2149,9 @@ compute_scalar_stats(VacAttrStatsP stats,
* least 2 instances in the sample. Also, we won't suppress values * least 2 instances in the sample. Also, we won't suppress values
* that have a frequency of at least 1/K where K is the intended * that have a frequency of at least 1/K where K is the intended
* number of histogram bins; such values might otherwise cause us to * number of histogram bins; such values might otherwise cause us to
* emit duplicate histogram bin boundaries. * emit duplicate histogram bin boundaries. (We might end up with
* duplicate histogram entries anyway, if the distribution is skewed;
* but we prefer to treat such values as MCVs if at all possible.)
*/ */
if (track_cnt == ndistinct && toowide_cnt == 0 && if (track_cnt == ndistinct && toowide_cnt == 0 &&
stats->stadistinct > 0 && stats->stadistinct > 0 &&