From: | Dirk Lutzebäck <lutzeb(at)aeccom(dot)com> |
---|---|
To: | pgsql-performance(at)postgresql(dot)org |
Subject: | why does explain analyze differ so much from estimated explain? |
Date: | 2004-09-29 15:55:45 |
Message-ID: | 415ADB01.9090001@aeccom.com |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-performance |
Hi,
I have a query where I do not understand that the rows number that
explain analyze finds differs so much from what explain estimates (3rd
nested loop estimates 1 row but in real it is 4222 rows). I did analyze
the tables (pgsql 7.4.1).
Here is the query:
explain analyze
SELECT fts.val_1, max(fts.val_2) AS val_2
FROM docobjflat AS fts,
boxinfo,
docobjflat AS ftw0,
docobjflat AS ftw, envspec_map
WHERE boxinfo.member=158096693
AND boxinfo.envelope=ftw.envelope
AND boxinfo.community=169964332
AND boxinfo.hide=FALSE
AND ftw0.flatid=ftw.flatid
AND fts.flatid=ftw.flatid
AND fts.docstart=1
AND envspec_map.spec=169964482
AND envspec_map.community=boxinfo.community
AND envspec_map.envelope=boxinfo.envelope
AND ftw0.val_14='IN-A01'
GROUP BY fts.val_1;
Query plan is attached.
Regards Dirk
Attachment | Content-Type | Size |
---|---|---|
qp | text/plain | 2.4 KB |
From | Date | Subject | |
---|---|---|---|
Next Message | Tom Lane | 2004-09-29 16:18:13 | Re: Poor Performance for large queries in functions |
Previous Message | John Meinel | 2004-09-29 14:56:27 | Re: [PERFORM] Poor Performance for large queries |