Bitmap Index

Users can speed up queries by creating a bitmap index This document focuses on how to create an index job, as well as some considerations and frequently asked questions when creating an index.

Glossary

• bitmap index: a fast data structure that speeds up queries

Basic Principles

Creating and dropping index is essentially a schema change job. For details, please refer to Schema Change.

Syntax

Create index

Create a bitmap index for siteid on table1

CREATE INDEX [IF NOT EXISTS] index_name ON table1 (siteid) USING BITMAP COMMENT 'balabala';

View index

Display the lower index of the specified table_name

SHOW INDEX FROM example_db.table_name;

Delete index

Delete the lower index of the specified table_name

DROP INDEX [IF EXISTS] index_name ON [db_name.]table_name;

Notice

• Currently only index of bitmap type is supported.
• The bitmap index is only created on a single column.
• Bitmap indexes can be applied to all columns of the Duplicate , Uniq data model and key columns of the Aggregate models.
• The data types supported by bitmap indexes are as follows:
  • TINYINT
  • SMALLINT
  • INT
  • BIGINT
  • CHAR
  • VARCHAR
  • DATE
  • DATETIME
  • LARGEINT
  • DECIMAL
  • BOOL
• The bitmap index takes effect only in segmentV2. The table's storage format will be converted to V2 automatically when creating index.

More Help

For more detailed syntax and best practices for using bitmap indexes, please refer to the CREARE INDEX / SHOW INDEX / DROP INDEX command manual. You can also enter HELP CREATE INDEX / HELP SHOW INDEX / HELP DROP INDEX on the MySql client command line.