From: "Alban Médici (NetCentrex)" <amedici@fr.netcentrex.net>
To: pgsql-benchmarks@postgresql.org
To: pgsql-performance@postgresql.org
Subject: stats on cursor and query execution troubleshooting
Date: Wed, 06 Oct 2004 12:15:31 +0200
Message-ID: <4163C5C3.3030304@fr.netcentrex.net> (raw)
Hi,
I'm looking for the statistic of memory, CPU, filesystem access while
executing some regular SQL query, and I want to compare them to
same kind of results while executing a cursor function.
The stat collector give me good results (sequencial scans , acceded
tuple .....) for regular query but nor for cursor (as explain in the
documentation)
For more results, i have activated some log level in the postgresql.conf :
show_query_stats = true
But I have some trouble in the results interpretation such as :
! system usage stats:
! 2.776053 elapsed 1.880000 user 0.520000 system sec
! [1.910000 user 0.540000 sys total]
! 0/0 [0/0] filesystem blocks in/out
! 5/1 [319/148] page faults/reclaims, 0 [0] swaps
! 0 [0] signals rcvd, 0/0 [0/0] messages rcvd/sent
! 0/0 [0/0] voluntary/involuntary context switches
! postgres usage stats:
! Shared blocks: 3877 read, 0 written, buffer hit rate = 0.00%
! Local blocks: 0 read, 0 written, buffer hit rate = 0.00%
! Direct blocks: 0 read, 0 written
Here is result done after fetching ALL a row with 178282 records in the
table.
looking at the i/o stat of linux I saw a filesystem access while
executing this request but not in the previous log !!!
! 0/0 [0/0] filesystem blocks in/out
I'm running postgresql 7.2.4 under redhat 7.2
Does am i wrong in my interpretation ?
Does any newest postgresql version could told me execution paln for a
fetch AND better stats ?
thx
Ps: please excuse my poor english
--
Alban Médici
R&D software engineer
------------------------------
you can contact me @ :
http://www.netcentrex.net
------------------------------
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To: pgsql-benchmarks@postgresql.org
Cc: amedici@fr.netcentrex.net, pgsql-performance@postgresql.org
Subject: Re: stats on cursor and query execution troubleshooting
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