Re: sequence indexes

mlw wrote:
>
> Hannu Krosing wrote:
> >
> > mlw wrote:
> > >
> > >
> > > Could one run a postgresql process in a lower priority process and
> > > perform lazy vacuums without affecting performance all that much?
> >
> > One must be very careful not to introduce reverse priority problems -
> > i.e. a
> > lower priority process locking some resource and then not letting go
> > while
> > higher priority processes are blocked from running due to needing that
> > lock.
> I understand that, hmm. I wonder if the lock code could boost the priority of a
> process which owns a lock.
>
> >
> > In my tests 1 vacuum process slowed down 100 concurrent pgbench
> > processes
> > by ~2 times.
>
> Is that good or bad?

I had hoped it to take somewhat proportional time, i.e. slow other
backends
down by 1/100.

> > > A live index compaction can be done by indexing the table with a
> > > temporary name rename the old index, rename the new index to the old
> > > name, and drop the old index.
> >
> > Isn't this what REINDEX command does ?
>
> REINDEX can't be run on a live system, can it?

It will probably lock something, but otherways I don't say why it can't.

You may have to add FORCE to the end of command thus:

reindex table tablename force;

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Hannu