| From: | Alvaro Herrera <alvherre(at)commandprompt(dot)com> |
|---|---|
| To: | Dimitri <dimitrik(dot)fr(at)gmail(dot)com> |
| Cc: | Aidan Van Dyk <aidan(at)highrise(dot)ca>, Simon Riggs <simon(at)2ndquadrant(dot)com>, Merlin Moncure <mmoncure(at)gmail(dot)com>, PostgreSQL Performance <pgsql-performance(at)postgresql(dot)org> |
| Subject: | Re: Any better plan for this query?.. |
| Date: | 2009-05-11 22:54:29 |
| Message-ID: | 20090511225429.GM8689@alvh.no-ip.org |
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| Thread: | |
| Lists: | pgsql-performance |
Dimitri escribió:
> Hi Aidan,
>
> thanks a lot for this detailed summary!
>
> So, why I don't use prepare here: let's say I'm testing the worst
> stress case :-) Imagine you have thousands of such kind of queries -
> you cannot prepare all of them! :-)
Thousands? Surely there'll be a dozen or three of most common queries,
to which you pass different parameters. You can prepare thoseu
> Now, as you see from your explanation, the Part #2 is the most
> dominant - so why instead to blame this query not to implement a QUERY
> PLANNER CACHE??? - in way if any *similar* query is recognized by
> parser we simply *reuse* the same plan?..
This has been discussed in the past, but it turns out that a real
implementation is a lot harder than it seems.
--
Alvaro Herrera http://www.CommandPrompt.com/
PostgreSQL Replication, Consulting, Custom Development, 24x7 support
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