| From: | Andres Freund <andres(at)2ndquadrant(dot)com> |
|---|---|
| To: | Sergey Konoplev <gray(dot)ru(at)gmail(dot)com> |
| Cc: | PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>, Maxim Boguk <maxim(dot)boguk(at)gmail(dot)com> |
| Subject: | Re: System catalog bloat removing safety |
| Date: | 2013-09-18 09:06:31 |
| Message-ID: | 20130918090631.GB13925@awork2.anarazel.de |
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| Thread: | |
| Lists: | pgsql-hackers |
Hi,
On 2013-09-17 23:12:24 -0700, Sergey Konoplev wrote:
> How safe is it to use the technique described by the link below with
> system catalog tables to remove bloat?
>
> (in a couple of words it is about moving tuples to the beginning of
> the table with a special way of updating)
>
> http://www.depesz.com/2010/10/17/reduce-bloat-of-table-without-longexclusive-locks/
>
> Are there any caveats?
At least for pg_index it's not safe, we use the xmin of rows when
indcheckxmin = true.
I am not aware of other cases, but I'd be hesitant to do so.
You have bloat because of lots of temporary tables IIRC?
Greetings,
Andres Freund
--
Andres Freund http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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