--On torsdag, januari 13, 2005 19.44.57 -0500 Tom Lane <tgl@sss.pgh.pa.us>
wrote:
> Palle Girgensohn <girgen@pingpong.net> writes:
>> Trying all this out, I realize that on 7.4.5, I can sometimes get
>> different results after `vacuum analyze' vs. a plain `analyze' (again,
>> not exactly the same data, and I cannot reproduce this on the other
>> machine with the data I sent you). It does not really relate to the
>> question above, but perhaps you can explain how come I get different
>> results?
>
> No surprise. vacuum analyze produces an exact total row count, whereas
> analyze can only produce an approximate total row count (since it only
> samples the table rather than groveling over every row). Sometimes the
> approximate count will be far enough off to affect the estimates.
Reasonable. Thanks for clarifying that. In the normal case, vacuum analyze
is better, I guess?
/Palle