Re: using an index worst performances

On Fri, 2004-08-20 at 05:37, Gaetano Mendola wrote:
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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.

We can test this.

What are the times without the index, with the index and with the higher
statistics value when using a prepared query?