| From: | Thomas Lockhart <lockhart(at)fourpalms(dot)org> |
|---|---|
| To: | "Gordon A(dot) Runkle" <gar(at)integrated-dynamics(dot)com> |
| Cc: | pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Odd statistics behaviour in 7.2 |
| Date: | 2002-02-13 14:41:34 |
| Message-ID: | 3C6A7B1E.EE0BEF92@fourpalms.org |
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| Lists: | pgsql-hackers |
> ... sometimes ... 'n_distinct' for this column
> gets a value of '-1' (desireable), and other times a value such as 56596
> or something.
> This is with the default setting for the statistics.
> Doing a 'SET STATISTICS 40' on the column got me to '-0.106047', which
> is better. But even so, the values do change somewhat over subsequent
> runs of VACUUM ANALYZE. And sometimes I get the coveted '-1'.
I'm guessing that your table is not randomly populated, so that the new
"statistically sampled ANALYZE" is sometimes getting a good sample (or
at least one with the result you want) and sometimes getting a terrible
one.
Tom?
- Thomas
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