Re: using an index worst performances

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Christopher Kings-Lynne wrote:

|>>> Without index: 1.140 ms
|>>> With index: 1.400 ms
|>>> With default_statistic_targer = 200:   1.800 ms
|>>
|>>
|>>
|>>
|>> Can I just check that 1.800ms means 1.8 secs (You're using . as the
|>> thousands separator)?
|>>
|>> If it means 1.8ms then frankly the times are too short to mean
|>> anything without running them 100 times and averaging.
|>
|>
|>
|>
|> It mean 1.8 ms and that execution time is sticky to that value even
|> with 1000 times.
|
|
| Given the almost irrelvant difference in the speed of those queries, I'd
| say that with the stats so high, postgres simply takes longer to check
| the statistics to come to the same conclusion.  ie. it has to loop over
| 200 rows instead of just 10.

The time increase seems too much.


Regards
Gaetano Mendola




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