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

Comparing the performance of using index with and without index in oracle, this article introduces the corresponding analysis and solution in detail, hoping to help more partners who want to solve this problem to find a more simple and feasible method.

Preface

The data structure of the Oracle storage index is the B* tree. The same is true of bitmap indexes, just indexes with different B* numbers of leaf nodes.

The index consists of root node, branch node and leaf node. The superior index block includes index data of the subordinate index block, and the leaf node includes index data and a rowid that determines the actual location of the row.

The purpose of using the index:

Speed up query speed

Reduce the Ipaw O operation

Eliminate disk sorting

When to use the index:

Number of records returned by query

Sorting table

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