On Dec 7, 2011, at 6:34 AM, Raj Mathur (राज माथुर) wrote: > Hi, > > I'm trying to correlate Call Data Records (CDRs) from two Asterisk > servers, one of which uses the other for telephony. The data is in > the tables cdr and cdr2. With some indexes, the query and explain > result are: > > explain analyse select cdr.calldate, cdr2.calldate, > (cdr2.calldate-cdr.calldate) as rtdur, cdr.clid, cdr.dst, cdr2.src, > cdr2.dst, cdr2.dstchannel, cdr2.lastapp, cdr2.duration, > cdr2.disposition from cdr, cdr2 where cdr2.calldate >= cdr.calldate > and cdr.clid=cdr2.clid and cdr.dst=substring(cdr2.dst from 4) order by > cdr.calldate, cdr2.calldate, cdr.clid limit 100; > > QUERY PLAN > > --------------------------------------------------------------------------------------------------------------------------------------------- > Limit (cost=46782.15..46782.40 rows=100 width=109) (actual > time=4077.866..4078.054 > rows=100 loops=1) > -> Sort (cost=46782.15..46785.33 rows=1272 width=109) (actual > time=4077.863..4077.926 > rows=100 loops=1) > Sort Key: cdr.calldate, cdr2.calldate, cdr.clid > Sort Method: top-N heapsort Memory: 42kB > -> Merge Join (cost=2.95..46733.54 rows=1272 width=109) (actual > time=0.070..3799.546 rows=168307 loops=1) > Merge Cond: (((cdr.clid)::text = (cdr2.clid)::text) AND > ((cdr.dst)::text = > "substring"((cdr2.dst)::text, 4))) > Join Filter: (cdr2.calldate >= cdr.calldate) > -> Index Scan using ick1 on cdr (cost=0.00..34667.86 > rows=208798 > width=43) (actual time=0.022..434.246 rows=208798 loops=1) > -> Index Scan using i2k1 on cdr2 (cost=0.00..9960.89 > rows=65449 width=88) > (actual time=0.011..391.599 rows=240981 loops=1) > Total runtime: 4078.184 ms > (10 rows) > > Is there any way to make this query faster? I already have an index > i2k1 on substring(cdr2.dst from 4), which is being used. > > Application > ----------- > > I'm looking for all caller records in cdr2 that have the same callerid > (clid) and destination (dst) and were started on cdr2 after they were > started on cdr. cdr2.dst is the same as cdr.dst but with a > 3-character prefix. > > Regards, > > -- Raj > -- > Raj Mathur || r...@kandalaya.org || GPG: > http://otheronepercent.blogspot.com || http://kandalaya.org || CC68 > It is the mind that moves || http://schizoid.in || D17F > > -- > Sent via pgsql-sql mailing list (pgsql-sql@postgresql.org) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-sql
You have a non-equi join in there (cdr2.calldate >= cdr.calldate). I would try to get rid of that. It's increasing the number of rows in the result set and will only get worse as your data set grows. Brent. -- Sent via pgsql-sql mailing list (pgsql-sql@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-sql
