From: eVl <evl.evl@gmail.com>
To: pgsql-performance@postgresql.org
Subject: optimization downgrade perfomance?
Date: Fri, 23 Sep 2005 01:27:16 +0300
Message-ID: <133614678.20050923012716@gmail.com> (raw)
Hello!
Got a DB with traffic statictics stored. And a SELECT statement which shows traffic volume per days also divided by regions - local traffic and global.
Thus SELECT statement returns about some (in about 10-20) rows paired like this:
ttype (text)| volume (int)| tdate (date)
----------------------------------------
local | xxxxx | some-date
global | xxxxx | some-date
When executing this SELECT (see SELECT.A above) it executes in about 700 ms, but when I want wipe out all info about local traffic, with query like this:
SELECT * FROM ( SELECT.A ) a WHERE type = 'global';
It executes about 10000 ms - more then 10 TIMES SLOWER!
Why this could be?
-------------------------------------------------
Initial Query - SELECT.A (executes about 700 ms)
SELECT
CASE is_local(aa.uaix) WHEN true THEN 'local'
ELSE 'global' END AS TType,
aa.cDate AS TDate,
SUM(aa.data) AS Value
FROM (
SELECT
a.uaix AS uaix,
cDate AS cDate,
SUM(a.data) AS data
FROM (
(
SELECT toIP AS uaix,
cDate AS cDate,
SUM(packetSize) AS data
FROM vw_stats
WHERE interface <> 'inet'
AND cdate = '01.09.2005'
AND fromIP << '192.168.0.0/16'
AND NOT (toIP << '192.168.0.0/16')
GROUP BY 1,2
)
UNION
(
SELECT fromIP AS uaix,
cDate AS cDate,
SUM(packetSize) AS data
FROM vw_stats
WHERE interface <> 'inet'
AND cdate = '01.09.2005'
AND toIP << '192.168.0.0/16'
AND NOT (fromIP << '192.168.0.0/16')
GROUP BY 1,2
)
) a
GROUP BY 1,2
) aa
GROUP BY 1,2
ORDER BY 1,2
-----------------------------------------------------------
Query with local info filtered (executes about 10000 ms)
SELECT * FROM (
<HERE PLACED SELECT.A>
) aaa WHERE aaa.TType = 'global';
-----------------------------------------------------------
Running Postgresql 8.0.3 on FreeBSD 5.3
--
Best regards,
eVl mailto:evl.evl@gmail.com
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To: pgsql-performance@postgresql.org
Cc: evl.evl@gmail.com
Subject: Re: optimization downgrade perfomance?
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