Here's how I determine that:
http://www.amazon.com/exec/obidos/ASIN/0130123811
http://otn.oracle.com/docs/products/oracle9i/doc_library/release2/server.920/a96533/toc.htm
Sorry for the RTFM, but what you're asking is a rather large topic, one
which I can't attempt to answer, at least, not while at work.
Jared
"BigP" <[EMAIL PROTECTED]>
Sent by: [EMAIL PROTECTED]
07/23/2002 06:58 PM
Please respond to ORACLE-L
To: Multiple recipients of list ORACLE-L <[EMAIL PROTECTED]>
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Subject: type of join in sql
can some body shed some light on how does the optimizer decides to choose
the kind of join i.e. nested loop, sort merge or hash join . In one of
queries if i tweak the join condition it changes the type of join and
start using index , otherwise it doesn't .
I thought it depends on statistics .. if optimize finds that are more
qualifying records in inner table then it will prefer to go for sort merge
and will do full scan of inner table , but if it thinks there are less
records in inner table it will user nested loop . am I correct ?
TIA ,
bp
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