Oracle Performance Optimization Operation 9: shielding useless indexes and optimizing oracle Performance

Source: Internet
Author: User

Oracle Performance Optimization Operation 9: shielding useless indexes and optimizing oracle Performance

Example of "oracle performance optimization operation 8"

In actual queries, there are also queries involving DisposalCourseFlag = 6. If the index on this field is used, it is unwise and the efficiency is extremely low.

In this case, we need to use a special method to shield the index so that ORACLE can select an index for other fields.

For example, if the field is numeric, after the field name of the expression, add "+ 0". If the field is numeric, It is a string over the sky: | ""

For example:

Select * from serviceinfo where DisposalCourseFlag + 0 = 6 and workNo = '36 ';

However, do not block the indexes that should be used. Otherwise, an inefficient full table scan will also occur.

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