What Is Cold and Hot Data Separation?

Scenarios

If there are some tables with almost no data reads or writes in your DB instance, you can use cold and hot data separation to dump their data to OBS. This helps reduce costs by managing cold and hot data more efficiently.

Introduction Video

How It Works

TaurusDB allows you to dump infrequently used InnoDB tables to OBS. These dumped tables are called cold tables.

Figure 1 Diagram

• Creating cold tables

  To free up space and reduce storage costs, you can select tables that do not need to be modified temporarily and take up a lot of space as cold tables. Such tables will be dumped to OBS.

• Migrating back cold tables

  To modify or frequently query certain cold tables, you can migrate the tables back to your DB instance, and the data of these tables will still be stored in OBS.

Disclaimer

• Cold table data cannot be migrated using DRS. During migration, if you want to retain cold table data of a source database, migrate cold tables back to the source database and then migrate the database using DRS.
• It takes longer to query data in cold tables. If there are too many cold tables, a large number of slow query logs may be generated.
• To prevent an operation failure, do not create or migrate back a cold table when any other operation is being performed on the instance.

Billing

Cold data stored on OBS is billed based on the backup space usage.

How to Use

• Dumping cold table data

  You can create cold tables on the console. The data of the cold tables is stored on OBS, freeing up storage space and reducing storage costs. For details, see Configuring a Cold Table on the Console.

• Querying cold table data

  Just like querying data from any ordinary table, you can run SELECT statements to query cold table data. For details, see Configuring a Cold Table Using SQL Statements.

• Modifying cold table data

  To modify a cold table that has been dumped to OBS, you can migrate the table back to your instance on the console, but the data of the table is still stored in OBS. To delete data from OBS, submit a service ticket.

• Deleting cold table data

  After a cold table is created, DDL statements cannot be executed on the cold table. This means that the table cannot be deleted directly, and neither can the database it belongs to.

  To delete a cold table, migrate it back and run the drop command.