Shulou(Shulou.com)05/31 Report--

In this issue, Xiaobian will bring you about how to create a composite index in Oracle. The article is rich in content and analyzed and described from a professional perspective. After reading this article, I hope you can gain something.

1. For composite indexes, the optimizer chooses to go indexed when all indexed columns appear in the Where constraint;

2. For composite indexes, the optimizer selects index walk when the leading column in the union index appears in the Where constraint, that is, when the union index is created;

3. When creating a composite index, the priority order of the indexed fields should be considered, and the fields that are often used as constraints should be placed in the first place; the columns with few duplicate values, i.e., high-cardinaltiy columns, should be placed forward, while the fields with many duplicate values should be placed backward;

4. For the same table, multiple different joint indexes can be created, provided that the number and order of indexed fields cannot be the same, otherwise an error is reported, ORA-01408.

The above is how to create a composite index in Oracle shared by Xiaobian. If you happen to have similar doubts, you may wish to refer to the above analysis for understanding. If you want to know more about it, please pay attention to the industry information channel.

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