MySQL Manual | 7.5.11.1 Physical Structure of an Index

7 MySQL Table Types
- 7.5 InnoDB Tables
  - 7.5.11 Table and Index Structures
    - 7.5.11.1 Physical Structure of an Index
    - 7.5.11.2 Insert Buffering
    - 7.5.11.3 Adaptive Hash Indexes
    - 7.5.11.4 Physical Record Structure
    - 7.5.11.5 How an Auto-increment Column Works in InnoDB

Previous / Next / Up / Table of Contents

7.5.11.1 Physical Structure of an Index

All indexes in InnoDB are B-trees where the index records are stored in the leaf pages of the tree. The default size of an index page is 16 KB. When new records are inserted, InnoDB tries to leave 1 / 16 of the page free for future insertions and updates of the index records.

If index records are inserted in a sequential (ascending or descending) order, the resulting index pages will be about 15/16 full. If records are inserted in a random order, then the pages will be 1/2 - 15/16 full. If the fillfactor of an index page drops below 1/2, InnoDB will try to contract the index tree to free the page.

User Comments

Add your own comment.

Top / Previous / Next / Up / Table of Contents