Re: How is statement level read consistency implemented? - Mailing list pgsql-general

From Alvaro Herrera
Subject Re: How is statement level read consistency implemented?
Date
Msg-id 20080422131014.GB5130@alvh.no-ip.org
Whole thread Raw
In response to Re: How is statement level read consistency implemented?  ("Roberts, Jon" <Jon.Roberts@asurion.com>)
Responses Re: How is statement level read consistency implemented?  ("Roberts, Jon" <Jon.Roberts@asurion.com>)
List pgsql-general
Roberts, Jon wrote:

> Back to PostgreSQL, when a vacuum is issued, the old deleted rows are
> removed.  This can be done with the autovacuum feature or manually.
>
> -Does vacuum make sure there are no long running queries referencing the
> deleted rows before it attempts to remove the old rows?

It does.

> -With autovacuum, does it skip these rows still being referenced in a
> transaction or does it wait?

It skips them, the idea being that a future vacuum will remove them.

--
Alvaro Herrera                                http://www.CommandPrompt.com/
PostgreSQL Replication, Consulting, Custom Development, 24x7 support

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