Slow Query Log

Scenarios

Slow query logs record statements whose execution period exceeds the value of operationProfiling.slowOpThresholdMs (100 ms by default). With slow query logs, you can identify and optimize slowly executed statements.

Constraints

• Community Edition DB instances allow you to view and export log details, enable the Show Original Log function, and download log files on the management console.
• The Show Original Log function cannot be enabled when you delete DB instances, add nodes, change DB instance class, rebuild secondary node, or the DB instance is frozen.
• When the Show Original Log function is being enabled, you cannot delete DB instances, add nodes, change DB instance class, or rebuild secondary node.

Showing Original Logs

• After Show Original Log is enabled, it cannot be disabled.
• After Show Original Log, original logs are displayed. The original slow query logs are displayed for your query and retained for 30 days.
• If the DB instance to which the slow query log belongs is deleted, related logs are also deleted after Show Original Log is enabled.

1. Log in to the DDS console.
2. On the Instance Management page, click the target DB instance.
3. In the navigation pane on the left, click Slow Query Logs.
4. On the displayed page, click Slow Query Logs. Then, click on the Log Details tab.
5. In the displayed dialog box, click Yes to enable the function of slowing original logs.

Viewing and Exporting Log Details

1. Log in to the DDS console.
2. On the Instance Management page, click the target DB instance.
3. In the navigation pane on the left, click Slow Query Logs.
4. On the Slow Query Logs page, set search criteria and click Search to view log information.
   • Log records of all shards of a cluster instance
   • Log records of all nodes of a replica set instance
   • Slow query logs of a node in different time periods
   • Slow query statements of the following level
     • All statement type
     • INSERT
     • QUERY
     • UPDATE
     • REMOVE
     • GETMORE
     • COMMAND
     • KILLCURSORS

5. On the Log Details tab, click in the upper right corner of the log list to export log details.
   • View the .csv file exported to your local PC.
   • A maximum of 10,000 log details can be exported at a time.

Downloading Logs

1. Log in to the DDS console.
2. On the Instance Management page, click the target Community Edition instance.
3. In the navigation pane on the left, click Slow Query Logs.
4. On the Slow Query Logs page, click the Log Files tab. Locate a log whose status is Preparation completed and click Download in the Operation column.
   • The system automatically loads the downloading preparation tasks. The loading duration is determined by the log file size and network environment.
     • During the downloading preparation, the log status is Preparing.
     • After the downloading preparation is complete, the log status is Preparation completed.
     • If the downloading preparation fails, the log status is Abnormal.
   • You can download only one log file from a node. The maximum size of a log file to be downloaded is 40 MB.
   • The download link is valid for 5 minutes. After the download link expires, a message is displayed indicating that the download link has expired. If you need to download the log, click OK.