Oracle performance optimization operation 11: like clause frontend matching as much as possible

Oracle performance optimization operation 11: like clause frontend matching as much as possible

Because the like parameter is frequently used, if the like clause can be indexed, the query efficiency will be greatly improved.

Example:

Select * from city where name like '% S % ';

The execution plan of the preceding query uses table access full. If it can be changed:

Select * from city where name like's % ';

Then the query execution plan will be changed to (index range scan), and the INDEX of the name field will be used successfully.

This means that the Oracle SQL optimizer identifies the like clause used for the index, as long as the matching end of the query is a specific value.

Therefore, when performing like queries, we should try to make the matching end of the query a specific value, that is, using like's % '.