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* execution time for first INSERT
@ 2011-07-08 11:23 Sergio Mayoral <mayoralstuttgart@yahoo.com>
0 siblings, 1 reply; 2+ messages in thread
From: Sergio Mayoral @ 2011-07-08 11:23 UTC (permalink / raw)
To: pgsql-performance
Hi,
i am using libpq library and postgresql 8.4 for my linux application running on ARM with 256 MB. I am just doing:
PQconnectdb();
PQexec(INSERT INTO table1 ....); (0.009661 sec.)
PQexec(INSERT INTO table1 ....); (0.004208 sec.)
PQexec(INSERT INTO table2 ....); (0.007352 sec.)
PQexec(INSERT INTO table2 ....); (0.002533 sec.)
PQexec(INSERT INTO table2 ....); (0.002281 sec.)
PQexec(INSERT INTO table2 ....); (0.002244 sec.)
PQexec(INSERT INTO table3 ....); (0.006903 sec.)
PQexec(INSERT INTO table3 ....); (0.002903 sec.)
PQfinnish();
I check the time for each PQexec with gettimeofday function and I always see that the first INSERT for each table needs longer than the next ones.
this must be something with the parser stage and since i am doing every time the same queries, I would like to know if there is a way to cache these queries in order to speed up the first INSERT.
Thanks in advance,
sma
^ permalink raw reply [nested|flat] 2+ messages in thread
* Re: execution time for first INSERT
@ 2011-07-09 00:40 Jeff Davis <pgsql@j-davis.com>
parent: Sergio Mayoral <mayoralstuttgart@yahoo.com>
0 siblings, 0 replies; 2+ messages in thread
From: Jeff Davis @ 2011-07-09 00:40 UTC (permalink / raw)
To: Sergio Mayoral <mayoralstuttgart@yahoo.com>; +Cc: pgsql-performance
On Fri, 2011-07-08 at 04:23 -0700, Sergio Mayoral wrote:
> this must be something with the parser stage and since i am doing
> every time the same queries, I would like to know if there is a way to
> cache these queries in order to speed up the first INSERT.
I doubt it's the parser.
Seeing as it's around a couple ms at minimum, it's probably some kind of
IO latency. You could see that by wrapping the statements in a big
transaction (BEGIN/END block) -- I bet the inserts go very quickly and
the final commit takes longer.
Regards,
Jeff Davis
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2011-07-08 11:23 execution time for first INSERT Sergio Mayoral <mayoralstuttgart@yahoo.com>
2011-07-09 00:40 ` Jeff Davis <pgsql@j-davis.com>
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