Обсуждение: Temporarily disable all table indices

Hello.

I need to perform a mass operation (UPDATE) on each table row. E.g. - modify one table column:

UPDATE tbl SET tbl_text = MD5(tbl_id);

The problem is that if this table contains a number of indices, such UPDATE is very very slow on large table.

I have to drop all indices on the table, then run the update (very quick) and after that - re-create all indices back. It is much more speedy. Unfortunately the table structure may change in the future (e.g. - new indices are added), so I don't know exactly in this abstraction layer, what indices to drop and what - to re-create.

Is any way (or ready piece of code) to save all existed indices, drop them all and then - re-create after a mass UPDATE?

Thanks!

pg_indexes.indexdef is exactly what I was looking for!

a (possibly slightly more user-friendly) alternative to the catalog
table is pg_dump, e.g.:

pg_dump -d your_db_name -t your_table -s | grep 'CREATE INDEX'



> -----Original Message-----
> From: pgsql-general-owner@postgresql.org
> [mailto:pgsql-general-owner@postgresql.org] On Behalf Of
> Dmitry Koterov
> Sent: Tuesday, March 27, 2007 3:10 AM
> To: Erik Jones
> Cc: Postgres General
> Subject: Re: [GENERAL] Temporarily disable all table indices
>
> Thanks!
>
> pg_indexes.indexdef is exactly what I was looking for!
>
>
> On 3/27/07, Erik Jones < erik@myemma.com
> <mailto:erik@myemma.com> > wrote:
>
>
>     On Mar 26, 2007, at 5:24 PM, Dmitry Koterov wrote:
>
>
>         Hello.
>
>         I need to perform a mass operation (UPDATE) on
> each table row. E.g. - modify one table column:
>
>         UPDATE tbl SET tbl_text = MD5(tbl_id);
>
>         The problem is that if this table contains a
> number of indices, such UPDATE is very very slow on large table.
>
>         I have to drop all indices on the table, then
> run the update (very quick) and after that - re-create all
> indices back. It is much more speedy. Unfortunately the table
> structure may change in the future ( e.g. - new indices are
> added), so I don't know exactly in this abstraction layer,
> what indices to drop and what - to re-create.
>
>         Is any way (or ready piece of code) to save all
> existed indices, drop them all and then - re-create after a
> mass UPDATE?
>
>
>
>     No, but you can use the pg_indexes view (
> http://www.postgresql.org/docs/8.2/interactive/view-pg-indexes
> .html
> <http://www.postgresql.org/docs/8.2/interactive/view-pg-indexe
s.html> ) to dynamically determine what indexes a table has.
>
>
>
>     erik jones <erik@myemma.com>
>     software developer
>     615-296-0838
>     emma(r)
>
>
>
>
>
>