VACUUM

When you need to immediately free up storage space or optimize query performance for time-series data, you can manually trigger a reorganization operation using the VACUUM TS DATABASES; command.

This command is particularly useful in the following scenarios:

• Freeing Space After Deleting Data or Dropping Tables: After executing DELETE or DROP operations, immediately remove deleted data to quickly reclaim storage space
• Data Organization After Bulk Writes: After large batch data writes, organize and sort data files to improve subsequent query performance

Privileges

N/A

Syntax

Parameters

N/A

Examples

The following examples demonstrate how to use the VACUUM command to free up storage space or optimize query performance.

• Free up storage space

  -- Execute delete operation
  DELETE FROM sensor_data WHERE ts < '2024-01-01';
  
  -- Immediately reorganize to reclaim storage space
  VACUUM TS DATABASES;
  

• Optimize query performance

  -- Bulk write data from multiple devices
  INSERT INTO sensor_data VALUES
      (NOW(), 25.5, 60.2, 101, 'temperature'),
      (NOW(), 26.1, 58.7, 102, 'temperature'),
      (NOW(), 24.8, 62.1, 103, 'temperature'),
      ...;
  
  -- Immediately reorganize to optimize data organization and improve query performance
  VACUUM TS DATABASES;