You have to run ANALYZE; on your db after a drop/reload to recollect
the stats. In the rest db, jus run ANALYZE; and then see how fast it
is. I'd guess that this is your issue.
Regards,
- Naz.
Andrew Edson wrote:
<blockquote cite="mid984673.72139.qm@web34205.mail.mud.yahoo.com"
type="cite">
I have a select statement, used in a Perl program, which is
supposed to find all records related to those in one table which have a
delete_dt field value of four years or older.
This is the select statement:
SELECT t2.dist_id, t1.clnt_seq, t2.cntrct_seq, t2.cntrct_id,
t3.aunit_seq, t1.person_seq, t1.addr_seq, t3.addr_seq, t4.frst_nm || '
' || t4.lst_nm AS name, t5.addr_1, t6.acntdel_dt FROM t1, t2, t3, t4,
t5, t6 WHERE t1.clnt_seq = t2.clnt_seq AND t2.cntrct_seq =
t3.cntrct_seq AND t3.aunit_seq = t6.aunit_seq AND t1.person_seq =
t4.person_seq AND t3.addr_seq = t5.addr_seq AND t1.active_flg =0 AND
t2.active_flg =0 AND t3.active_flg = 0 AND t6.acntdel_dt < now() -
'4 years'::interval order by t2.cntrct_id asc;
I'm working on a test box at the moment; the db I am using was
made by dumping the production db and copying it over to the test box
to be loaded into a newly-created db there. It took a while for me to
get the original Perl program working, as I don't really understand
Perl, but after I did so, I dropped the db and reloaded it again off of
the original files, so I could try another test run and pay attention
to what's happening.
On the original load of the test db, the query above had a run
time of roughly 3, 3.5 minutes before giving results. Considering the
size of the db it's searching through, I feel that's fairly reasonable,
especially since that's about what the production db does on the same
query. Now, after the drop/recreate, the test db is taking somewhat
longer to give back its results; just shy of 7 minutes, if I've done
the math correctly. (Timing results - Time: 417531.436 ms)
I'm the only person working on this particular box at this
point. This problem did not start until I reloaded the db from the
original files. Obviously, I managed to miss something in the
drop/reload process, but I have no clue what. I'm running a vacuum
full analyze at the moment; if anyone has any other suggestions as to
what I could do to solve this (admittedly minor) problem, I would be
grateful to hear them.
Thank you for your consideration.
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