Re: poor pefrormance with regexp searches on large tables

From: "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov>
To: "Grzegorz Blinowski" <g(dot)blinowski(at)gmail(dot)com>, <pgsql-performance(at)postgresql(dot)org>
Subject: Re: poor pefrormance with regexp searches on large tables
Date: 2011-08-11 13:56:14
Message-ID: 4E43992E020000250003FD9D@gw.wicourts.gov
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-performance

Grzegorz Blinowski <g(dot)blinowski(at)gmail(dot)com> wrote:

> A small followup regarding the suggestion to turn off compression
> - I used:
>
> ALTER TABLE archive_tender ALTER COLUMN subject SET STORAGE
> EXTERNAL
>
> to turn off compression, however I get an impression that "nothing
> happend". When exactly this alteration takes effect? Perhaps I
> should reload the entire db from backup to change the storage
> method?

Yeah, the storage option just affects future storage of values; it
does not perform a conversion automatically. There are various ways
you could cause the rows to be re-written so that they use the new
TOAST policy for the column. One of the simplest would be to do a
data-only dump of the table, truncate the table, and restore the
data. If that table is a big enough portion of the database, a
pg_dump of the whole database might be about as simple.

-Kevin

In response to

Responses

Browse pgsql-performance by date

  From Date Subject
Next Message Antonin Faltynek 2011-08-11 14:46:38 Streaming replication performance
Previous Message Grzegorz Blinowski 2011-08-11 08:39:34 Re: poor pefrormance with regexp searches on large tables