----- Original Message -----
Sent: Sunday, August 10, 2003 10:54
PM
Subject: stats and query plans
hi
a very basic question
i have faced this issue a few times in the last couple of weeks. we have
a few queries that seem to run remarkable well in rule based optimisation than
in choose based optimisation. the queries, with all the object stats collected
upto date, never returns a result while when i deleted all stats it returns a
result in no time.The plans are diffrent and w/o stats indexes are being
used.
when this happens in the same system what are the things i should check.
is it not recommended that oracle CBO is the best way to go in performance
tuning and query optimisations.then how come rule based turns out to be
efficient.surely i havent generated 10053 trace and gone through it but it
doesnt make sense why CBO falters. Logically speaking when rule based path
gives a result,CBO should choose that explain plan.
can someone throw some light on this
thanks
sai
