Re: I don't understand this

Uros Gruber wrote:
> Hi!
>
> i create some table with primary key and one index key
> Then i insert data and try some explain on my select.
>
> it tells me that index was used.
>
>
> then i do some other queries and vacuum and when i try again
> SAME explain it prints that it was used Seq Scan
>
> It this normal or what. Or is some kind of a bug.

Yes, this is normal.

The statistics defaults for an un-vacuumed table usually
cause the optimizer to use an index scan. When you analyze
the table later, the statistics reflect the real status and
for very small tables, a sequential scan is normally better
than an index scan.

Jan

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