Re: Re: Heaps of read() syscalls by the postmaster

If we create a unique index on a column, seems we could update
pg_statistic automatically to mark it as unique.

> "Matthias Urlichs" <smurf(at)noris(dot)net> writes:
> >> Do we shrink system tables on vacuum ?
> >>
> > If the user calling the VACUUM has access rights to them, yes.
>
> But the indexes don't shrink (same problem as for user indexes).
>
> VACUUM doesn't really make any distinction between system tables and
> user tables; they're all handled the same way. IIRC, the only
> special-case in 7.0 is that it doesn't try to compute pg_statistic
> entries for pg_statistic ;-)
>
> >> It's possible that running some benchmark that creates/drops tables
> >> repetedly will blow up the size of system tables incl. pg_attribute.
>
> Yes, if you don't vacuum them every so often...
>
> But what I don't understand is why a simple INSERT is doing a sequential
> scan of pg_attribute. Presumably the parser needs to find out what the
> table's columns are ... but why isn't the catcache providing the data?
> Needs to be looked at.
>
> regards, tom lane
>

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