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| Stored Outlines and Plan Stability - Use stored outlines to maintain consistent execution plans regardless of changes in the system environment or associated statistics. |
Arindam Mukherjee said... It's really worth reading and it has helped me a lot get a clear picture of this topic. I highly appreciate this effort. |
Rich said... Think you should consider removing the reference to query_rewrite_enabled. This is not specifically required to create or use a stored outline and, at 9i at least, can cause real problems with other queries. |
Tim... said... Hi.According to the 10g manual it is necessary: http://download-west.oracle.com/docs/cd/B14117_01/server.101/b10752/outlines.htm#15583 Cheers Tim... |
rich said... Tim,Thanks for replying. I believe this is what the doc you refer to says: "Settings for several parameters, especially those ending with the suffix _ENABLED, must be consistent across execution environments for outlines to function properly. These parameters are: QUERY_REWRITE_ENABLED STAR_TRANSFORMATION_ENABLED OPTIMIZER_FEATURES_ENABLE" Sorry to be pedantic but I recently fell into this trap and had to raise a tar to confirm I did not need query_rewrite. |
Richard said... You have this:-- Switch on automatic creation of stored outlines. ALTER SYSTEM SET create_stored_outlines=TRUE; ALTER SESSION SET create_stored_outlines=TRUE; -- Switch on automatic creation of stored outlines. ALTER SYSTEM SET create_stored_outlines=FALSE; ALTER SESSION SET create_stored_outlines=FALSE; Second one needs to say "Switch off ..." . Nice article! |
Ashish Kohli said... Excellent stuff... |
sunil said... How do i enable a session X to use the outline...For example I want BLAKE session to use the sored oultline. But, i cannot use alter session from his session.... thx |
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