|From:||Konstantin Knizhnik <k(dot)knizhnik(at)postgrespro(dot)ru>|
|Subject:||Re: Cached plans and statement generalization|
|Views:||Raw Message | Whole Thread | Download mbox | Resend email|
On 26.04.2017 10:49, Konstantin Knizhnik wrote:
> On 26.04.2017 04:00, Tsunakawa, Takayuki wrote: Are you considering
> some upper limit on the number of prepared statements?
> In this case we need some kind of LRU for maintaining cache of
> autoprepared statements.
> I think that it is good idea to have such limited cached - it can
> avoid memory overflow problem.
> I will try to implement it.
I attach new patch which allows to limit the number of autoprepared
statements (autoprepare_limit GUC variable).
Also I did more measurements, now with several concurrent connections
and read-only statements.
Results of pgbench with 10 connections, scale 10 and read-only
statements are below:
As you can see, autoprepare provides more than 2 times speed improvement.
Also I tried to measure overhead of parsing (to be able to substitute
all literals, not only string literals).
I just added extra call of pg_parse_query. Speed is reduced to 181k.
So overhead is noticeable, but still making such optimization useful.
This is why I want to ask question: is it better to implement slower
but safer and more universal solution?
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company
|Next Message||Bruce Momjian||2017-04-26 10:30:34||Re: PG 10 release notes|
|Previous Message||Antonin Houska||2017-04-26 10:28:02||Re: Partition-wise aggregation/grouping|