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I have a query of 18 table joins and it utilizes the Indexes in Development Database but it does not use the Indexes in QA and Production Database even though Tablea are the same, Indexes are the same and Same Types.
Logically Every thing is same in all three databases but Query Does not use the Indexes in QA and Production but works fine in Development..
Can any one let me know WHY?
Please respond me ASAP.. at [email protected]
Thanks.
Okay, so you say that the tables and indexes are defined the same. The remaining key variables that affect the optimizer are:
- Data
- Statistics
- Initialization parameters
Check for differences in these three areas for your culprit.
Is the data radically different. Are there extreme values in the one db that are not in the other. Are the stats current in both? Are all the optimizer_* initialization parameters the same on both servers?
- Chris
at the very end (or beginning), use outlines:
we had a discussion with chrislong a time ago called "CBO reliability" about fixed plans (my preference) and CBO generated plans (chrislong's preference). Can take a look into it.