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

From Roberts, Jon
Subject Re: How is statement level read consistency implemented?
Date
Msg-id 1A6E6D554222284AB25ABE3229A92762E9A1F9@nrtexcus702.int.asurion.com
Whole thread Raw
In response to Re: How is statement level read consistency implemented?  (Alvaro Herrera <alvherre@commandprompt.com>)
Responses Re: How is statement level read consistency implemented?  (Alvaro Herrera <alvherre@commandprompt.com>)
List pgsql-general
> > 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.
>

Awesome.  In a large data warehouse, the snapshot too old error is very
annoying and I'm glad PostgreSQL is superior to Oracle in this regard.
:)



Jon

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