RE: [SQL] Deleting indexes before vacuum?

> -----Original Message-----
> From: owner-pgsql-sql@postgreSQL.org [mailto:owner-pgsql-sql@postgreSQL.
> org]On Behalf Of Tom Lane
> Sent: Sunday, November 21, 1999 2:01 AM
> To: Oleg Bartunov
> Cc: Matthew Hagerty; pgsql-sql@postgreSQL.org
> Subject: Re: [SQL] Deleting indexes before vacuum?
>
>
> Oleg Bartunov <oleg@sai.msu.su> writes:
> > The question is: what's the right way to do drop index/vacuum/create ?
> > Do I need transaction ?
>
> VACUUM should not be run inside a transaction block.  (I am planning to
> make the code enforce this for 7.0, but it doesn't yet.)  So you can't
> protect the whole sequence with a transaction.  AFAICS the only real
> problem is that if you are depending on UNIQUE indexes to catch
> attempts to insert duplicate data, an insertion that got in between
> the drop and recreate wouldn't get checked.
>
> I have been toying with the notion of ripping out the existing VACUUM
> index handling code and putting in fresh code that would simply do an
> index drop and rebuild ;-).  This could happen inside VACUUM's exclusive
> lock on the table, so it'd be perfectly safe whereas doing it the manual
> way is not.  But I do not want to do this unless Vadim approves it as a
> good idea --- perhaps the existing index-vacuuming code can be fixed to
> be an even better solution than this.  I haven't looked at the code to
> understand why it's so slow or whether there's a way to make it better.
>

Shouldn't vacuum preserve consistency even in case of abort ?
Currently PostgreSQL doesn't do little in case of abort(even commit also ?).
So I think it's a strong limitation.

It's well known that rebuilding indexes is faster than insert/deleting
many index tuples.
I have thought rebuilding indexes in vacuum for half a year.
But I don't have a reasonable solution yet.

Rebuiding indexes in vacuum has a big flaw that index may vanish in
case of abort and we may have to recreate index manually.

Regards.

Hiroshi Inoue
Inoue@tpf.co.jp