| From: | Simon Riggs <simon(at)2ndQuadrant(dot)com> |
|---|---|
| To: | Pavan Deolasee <pavan(dot)deolasee(at)gmail(dot)com> |
| Cc: | Robert Haas <robertmhaas(at)gmail(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Set visibility map bit after HOT prune |
| Date: | 2012-12-19 23:35:39 |
| Message-ID: | CA+U5nMLvN0Esd2do=_HaLeOs=OS2H6AADxCrM3vKyQ78K1_s-Q@mail.gmail.com |
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| Lists: | pgsql-hackers |
On 19 December 2012 17:26, Pavan Deolasee <pavan(dot)deolasee(at)gmail(dot)com> wrote:
> We definitely
> made great progress by having HOT
Yes, definitely. Great work. That is not for debate.
> But I think generally HOT made great difference to the
> system as a whole, may be at a cost of slowdown for some read-only,
> select queries. And HOT prune is not the only operation that we do in
> foreground. We also set hint bits and make buffers dirty in an
> otherwise read-only queries.
And those last things are being debated hotly. We definitely need to
ask whether the way things are now can be tweaked to be better. The
major mechanics need not be reviewed, but the tradeoffs and balances?
Definitely.
Anything we do in foreground needs evaluation. Assuming eager actions
give a good payoff is not always a useful thought.
--
Simon Riggs http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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