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Viewing and Downloading Slow Query Logs

Updated at: May 26, 2020 GMT+08:00

Scenarios

Slow query logs record statements that exceed long_query_time (1 second by default). You can view log details to identify statements that are executing slowly and optimize the statements. You can also download slow query logs for service analysis.

Parameter Description

Table 1 Parameters related to Microsoft SQL Server slow queries

Parameter

Description

long_query_time

Specifies the time greater than or equal to which slow query logs are recorded. The precision is microsecond. The default value is 1s. When the execution time of an SQL statement exceeds the value of this parameter, the SQL statement is recorded in slow query logs.

You can modify the slow log threshold as required.

  1. Log in to the management console.
  2. Click in the upper left corner and select a region and a project.
  3. Click Service List. Under Database, click RDS. The RDS console is displayed.
  4. On the Instance Management page, click the target DB instance.
  5. In the navigation pane on the left, choose Logs. On the Slow Query Logs page, click in the Threshold of Slow Query Log (long_query_time) field to change the threshold.
    • To submit the change, click .
    • To cancel the change, click .
    NOTE:

    The recommended value is 1s. The lock wait time is not calculated into the query time.

Viewing Slow Query Logs

  1. Log in to the management console.
  2. Click in the upper left corner and select a region and a project.
  3. Click Service List. Under Database, click RDS. The RDS console is displayed.
  4. On the Instance Management page, click the target DB instance.
  5. In the navigation pane on the left, choose Logs. On the Slow Query Logs page, click to enable the slow query log function.
  6. The generated slow query logs are displayed.

    Figure 1 SQL Server slow query log

    Enabling slow query log slightly affects DB instance performance.

  7. Connect to the DB instance through the Microsoft SQL Server client. For details, see Connecting to a DB Instance Through a Public Network.
  8. After the DB instance is connected, run the following command to view slow query log details:

    select * from ::fn_trace_gettable('D:\SQLTrace\audit\XXX', default)

    XXX indicates the name of the slow query log recorded in 6.

    Example:

    select * from ::fn_trace_gettable('D:\SQLTrace\audit\SQLTrace.trc', default)

    The result is shown in Figure 2.

    Figure 2 Slow query log details

Downloading a Log

  1. Log in to the management console.
  2. Click in the upper left corner and select a region and a project.
  3. Click Service List. Under Database, click RDS. The RDS console is displayed.
  4. On the Instance Management page, click the target DB instance.
  5. In the navigation pane on the left, choose Logs. On the Slow Query Logs page, click to enable the slow query log function.

    Enabling slow query log slightly affects DB instance performance.

  6. Locate a log to be downloaded and click Download in the Operation column.

    1. 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.
    2. In the displayed dialog box, click OK to download the log whose status is Preparation completed. If you click Cancel, the system does not download the log.

      The download link is valid for 5 minutes. After the download link expires, a message is displayed indicating that the download link has expired. You can close the window and repeat the procedure 6 to try to download a log again.

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