Bruce Momjian wrote:
Maybe I am mixing up separate concepts (are bound variables and prepared
statements different concepts?) here. I also do not really understand if
that means that oracle does not store a query plan for a prepared query
or if it just does some special handling in case it knows that a
prepared statement column is known to have a highly varying selectivity
per value.
What the Oralce manual means I think is that the plan of the query is
delayed until the _first_ EXECUTE, so it has some values to use in the
optimizer. The problem is that later queries might use constants of
greatly different cardinality.
ok .. which just goes to tell to not use prepared statements for a
column with highly varying selectivity ..?
or is there a realistic shot at fixing this use case?
regards,
Lukas
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