Re: planstats.sgml

Tatsuo Ishii <ishii@postgresql.org> writes:
> While reading planstats.sgml, I encounted a sentence which I don't
> understand.

>     These numbers are current as of the last <command>VACUUM</> or
>     <command>ANALYZE</> on the table.  The planner then fetches the
>     actual current number of pages in the table (this is a cheap operation,
>     not requiring a table scan).  If that is different from
>     <structfield>relpages</structfield> then
>     <structfield>reltuples</structfield> is scaled accordingly to
>     arrive at a current number-of-rows estimate.  In this case the value of
>     <structfield>relpages</structfield> is up-to-date so the rows estimate is
>     the same as <structfield>reltuples</structfield>.

> I don't understand the last sentence (In this case...). For me it
> seems it is talking about the case when replages is not different from
> what the planner fetches from the table. If so, why "In this case"?

I think what it meant is "In the example above, ...".  Feel free to
change it if you think that is clearer.
        regards, tom lane