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Don Burleson Blog 








Important: Query gives wrong result

Oracle guru Allen Brandon has published a fantastic write-up of a serious Oracle issue whereby SQL queries can return incorrect result when using table prefetching:

"There is a bug in many (if not all) versions of 9.2, 10.1 and 10.2, on all platforms, that causes queries to intermittently return the wrong results when table prefetching is used, which is enabled by default.

The likelihood of encountering this is high since the feature at fault (table prefetching) is enabled by default and it doesn't require any exotic query to expose it - just a simple join of a few tables and the right mix of stats, bind variables, etc. for the CBO to come up with an explain plan that uses table prefetching.

 . . .

setting the hidden parameter _table_lookup_prefetch_size=0.
Check out MOSC# 406966.1



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