Oh wise Perl magicians
I have a query that looks something like this :
select ra.value, ra.ra_id, q.id as q_id, q.qid , q.parent, q.q, q.type
+, p.qid as pqid, if($ifstatement,'1','0') as selection , r.rpid from
+r, ra, q left join q p on q.parent = p.id where r.id = ra.ra_id and r
+.q in (3,4,5) and ra.q = q.id order by ra.ra_id ASC,selection desc;
The 'explain' shows a good and nice run (no full table scans), and in mySQL it takes about 3 seconds to run (about 130.000 records) using mysql -u user -p database < q.sql > output.txt
When doing this from whithin Perl however,
my $bm= DEBUG_Benchmark->new();
$sth = $dbh->prepare("select ra.value, ra.ra_id, q.id as q_id, q.qid ,
+ q.parent, q.q, q.type, p.qid as pqid, if($ifstatement,'1','0') as se
+lection , r.rpid from r, ra, q left join q p on q.parent = p.id where
+ r.id = ra.ra_id and r.q in (3,4,5) and ra.q = q.id order by ra.ra_id
+ ASC,selection desc");
It takes about 12 seconds to run (Only the prepare and the execute, i did not even loop over the resultset).
Any idea on how to speed this up? Whit a smaller resultset, it takes about .003 seconds to prepare / execute.
I know DBI should be able to do mutch better, any ideas on how i can get a better result?
I run this on an UML (user mode linux), so there is a lot of overhead in the disk io, however, the same problem occurs on a 'normal' debian distribution, the difference is big. (2 sec - 8 sec)
The resultset of the query looks like this:
*** UPDATE ***
value ra_id q_id qid parent q(4,5,6)type pqid sel
1 5501 1918917 34 0 4 6 NULL 1 ed94d62745f5
1 5501 1918918 33 0 4 6 NULL 1 ed94d62745f5
4 5501 1918915 32 0 4 6 NULL 1 ed94d62745f5
2 5501 1918940 31 0 4 6 NULL 1 ed94d62745f5
6 5501 1918916 30 0 4 6 NULL 1 ed94d62745f5
Ah FOUND IT!!! Here is the answer!!!
"We all agree on the necessity of compromise. We just can't agree on when it's necessary to compromise." - Larry Wall.
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