Oracle 9: Date Compare Performance
Date: Thu, 29 Jan 2009 06:36:29 -0800 (PST)
I ve got a table named schedule which includes epg information round
about 60.000 records. I would like to check if there are logical
One kind of conflict is that a program start stop time frame includes other programs...
Therefore I ve got this select statement: SELECT Distinct schd.chan_recid, schd.SCHD_START_DATE,
schd.SCHD_END_DATE, schd.schd_import_refnum, include_schd.schd_import_refnum as overlapping_schd_import_refnum, include_schd.schd_start_date as overlapping_start,include_schd.schd_end_date as overlapping_end FROM SCHEDULE schd
LEFT JOIN ova_schedule include_schd
on (schd.CHAN_RECID = include_schd.CHAN_RECID and
include_schd.schd_recid != schd.schd_recid and include_schd.schd_start_date >= schd.schd_start_date and include_schd.schd_end_date <= schd.schd_end_date)WHERE (include_schd.schd_import_refnum is not null)
To my suprise it takes over a minute to complete!!!
If I change the date compares from >= and <= to just = : include_schd.schd_start_date = schd.schd_start_date and include_schd.schd_end_date = schd.schd_end_date
It just takes round about 10 seconds.
Does anybody know why the date comparison operators > and < are so slow?
Does anybody have a workaround?
Thanks a lot in advance...
Volker Received on Thu Jan 29 2009 - 08:36:29 CST