[pgpool-hackers: 361] Re: Auto-learning database-modifying functions

[Ahsan Hadi]

On Wed, Sep 11, 2013 at 7:57 PM, Tatsuo Ishii <ishii at postgresql.org> wrote:

> > As I understand it, PgPool in read-balancing mode needs to know which
> > function calls modify the database so it knows to send these to the
> > write server.
>

Yeah i believe that is managed through the white and black list...


> >
> > I know you can specify a pattern to identify database-modifying
> > functions, but I am wondering if you could send queries containing
> > questionable functions to the read-only server, and if you get a
> > read-only error, then send them to the write server.  A more interesting
> > approach would be to remember which functions cause these failures and
> > then auto-route them to the write server when we see them again.
>

How would we decide which functions are questionable?


>
> Interesting idea. Even we could overcome current limitation of
> pgpool-II: cannot detect write functions used in a view by using the
> technique.
>
> > I believe this would give PgPool the ability to _learn_ which functions
> > need to go to the write server.  Is this already implemented?
>

Are you suggesting that we do this in addition to technique currently
available for load balancing?

>
> No.
> --
> Tatsuo Ishii
> SRA OSS, Inc. Japan
> English: http://www.sraoss.co.jp/index_en.php
> Japanese: http://www.sraoss.co.jp
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>



-- 
Ahsan Hadi
Snr Director Product Development
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