Re: pg_rewarm status
| От | Jeff Janes |
|---|---|
| Тема | Re: pg_rewarm status |
| Дата | |
| Msg-id | CAMkU=1xOWa5iHQ0hP+5xTDVm3=75RXNB1UG=Qe_oYJF5hXkZGg@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: pg_rewarm status (Jim Nasby <jim@nasby.net>) |
| Ответы |
Re: pg_rewarm status
|
| Список | pgsql-hackers |
On Tue, Dec 17, 2013 at 8:02 AM, Jim Nasby <jim@nasby.net> wrote:
On 12/17/13, 8:34 AM, Robert Haas wrote:We've had to manually code something that runs EXPLAIN ANALYZE SELECT * from a bunch of tables to warm our caches after a restart, but there's numerous flaws to that approach obviously.On Tue, Dec 17, 2013 at 12:09 AM, Amit Kapila <amit.kapila16@gmail.com> wrote:I have used pg_prewarm during some of work related to Buffer Management and
other performance related work. It is quite useful utility.
+1 for reviving this patch for 9.4
Any other votes?
Unfortunately, what we really need to warm isn't the PG buffers, it's the FS cache, which I suspect this won't help. But I still see where just pg_buffers would be useful for a lot of folks, so +1.
Since it doesn't use directIO, you can't warm the PG buffers without also warming FS cache as a side effect. That is why I like 'buffer' as the default--if the data fits in shared_buffers, it warm those, otherwise it at least warms the FS. If you want to only warm the FS cache, you can use either the 'prefetch' or 'read' modes instead.
Cheers,
Jeff
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