First off, this is posted to the wrong list -- this list is for
discussion of development of the PostgreSQL product. There is a
list for performance questions where this belongs:
pgsql-performance@postgresql.org. I'm moving this to the
performance list with a blind copy to the -hackers list so people
know where the discussion went.

Nick Raj wrote:
When i execute the query first time, query takes a quite longer
time but second time execution of the same query takes very less
time (despite execution plan is same)
Why the same plan giving different execution time? (Reason may be
data gets buffered (cached) for the second time execution) Why
there is so much difference?
Because an access to a RAM buffer is much, much faster than a disk
access.
Which option will be true?
It depends entirely on how much of the data needed for the query is
cached. Sometimes people will run a set of queries to "warm" the
cache before letting users in.
MY postgresql.conf file having setting like this (this is original
setting, i haven't modify anything)
shared_buffers = 28MB
#work_mem = 1MB # min 64kB
#maintenance_work_mem = 16MB # min 1MB
If you're concerned about performance, these settings (and several
others) should probably be adjusted:

http://wiki.postgresql.org/wiki/Tuning_Your_PostgreSQL_Server

-Kevin

Search Discussions

Related Discussions

Discussion Navigation
viewthread | post
posts ‹ prev | 1 of 1 | next ›
Discussion Overview
grouppgsql-performance @
categoriespostgresql
postedJun 6, '11 at 3:49p
activeJun 6, '11 at 3:49p
posts1
users1
websitepostgresql.org
irc#postgresql

1 user in discussion

Kevin Grittner: 1 post

People

Translate

site design / logo © 2022 Grokbase