Re: Return of the Solaris vacuum polling problem -- anyone remember this?

Excerpts from Bruce Momjian's message of lun ago 23 14:55:55 -0400 2010:

> OK, I have attached a proposed patch to improve this.  I moved the
> pg_clog mention to a new paragraph and linked it to the reason the
> default is relatively low.
> 
> Comments?

I think the new para doesn't make much sense, in context.  Why does it
say "freeze"?  How can we expect users to understand how that is
related to this parameter?

> --- 4150,4165 ----
>          <para>
>           Specifies the maximum age (in transactions) that a table's
>           <structname>pg_class</>.<structfield>relfrozenxid</> field can
> !         attain before a <command>VACUUM</> freeze operation is forced
> !         to prevent transaction ID wraparound within the table.
> !         Note that the system will launch autovacuum processes to
> !         prevent wraparound even when autovacuum is otherwise disabled.
> !        </para>
> ! 
> !        <para>
> !         Vacuum freeze also allows removal of old files from the
> !         <filename>pg_clog</> subdirectory, which is why the default
> !         is a relatively low 200 million transactions.
>           This parameter can only be set at server start, but the setting
>           can be reduced for individual tables by
>           changing storage parameters.

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Álvaro Herrera <alvherre@commandprompt.com>
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