Help Center/ Relational Database Service/ User Guide/ Working with RDS for MySQL/ Log Management/ Viewing and Downloading Slow Query Logs
Updated on 2025-11-11 GMT+08:00
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Viewing and Downloading Slow Query Logs

Scenarios

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

Slow query logs generated within the last month can be viewed.

RDS supports the following types of statements: All types, SELECT, INSERT, UPDATE, DELETE, CREATE, CALL, ALTER, TRUNCATE, RENAME, FLUSH, EXPLAIN, LOCK, GRANT, REVOKE, COMMIT, ROLLBACK, DROP, and WITH.

Constraints

Original logs will be automatically deleted 30 days later. If the instance is deleted, its logs are also deleted.

Parameter Description

Table 1 Parameters related to slow queries

Parameter

Description

long_query_time

Specifies how many microseconds a SQL query has to take to be defined as a slow query log. 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.

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

Modifying long_query_time takes effect globally. After the modification, the new value is applied to new connections. The existing connections still use the old value.

log_queries_not_using_indexes

Specifies whether to record the slow query without indexes. The default value is OFF.

log_throttle_queries_not_using_indexes

Limits the number of SQL statements without indexes per minute that can be written to the slow query log. The default value is 0.

Viewing Log Details

  1. Log in to the management console.
  2. Click in the upper left corner of the page and choose Databases > Relational Database Service.
  3. On the Instances page, click the target instance name.
  4. In the navigation pane on the left, choose Logs. On the Slow Query Logs page, click the Log Details tab.

    • You can view the slow query log records of a specified statement or a specific time period.
    • The Scanned Rows column indicates the number of data rows that are actually accessed and processed during SQL execution.
    • Only SELECT statements return the number of result rows (column Result Rows). The number of result rows for the INSERT, UPDATE, DELETE, and CREATE statements is 0 by default.
    • Slow query logs record executed statements whose execution duration exceeds the threshold.
    • The long_query_time parameter determines when a slow query log is recorded. Changes to this parameter do not affect already recorded logs. For example, if the value of this parameter is changed from 1 to 0.1 (unit: second), RDS starts recording statements that meet the new threshold and still displays the previously recorded logs that do not meet the new threshold.
    • A maximum of 2,000 slow log records can be queried.
    • To export log details, . You can export them by time range. A maximum of 1,000 records can be exported at a time.

Viewing Statistics

  1. Log in to the management console.
  2. Click in the upper left corner of the page and choose Databases > Relational Database Service.
  3. On the Instances page, click the target instance name.
  4. In the navigation pane on the left, choose Logs. On the Slow Query Logs page, click Statistics to view details.

    • On the Statistics page, only one of the SQL statements of the same type is displayed as an example. For example, if two select sleep(N) statements, select sleep(1) and select sleep(2), are executed in sequence, only select sleep(1) will be displayed.
    • No. and Ratio of SQL Executions shows the ratio of the slow executions to the total executions of the SQL statement.
    • On the Statistics page, only the latest 5,000 slow SQL queries within a specified period are analyzed.
    • To export statistics, . You can export them by time range. A maximum of 1,000 records can be exported at a time.
    • You can filter slow log statistics by specifying a database name (which cannot contain any special characters), statement type, or time period. The database name supports only exact search.
    • If any database name in the slow log statistics contains special characters(such as < > '), the special characters will be escaped.

  1. Log in to the management console.
  2. Click in the upper left corner of the page and choose Databases > Relational Database Service.
  3. On the Instances page, click the target instance name.
  4. In the navigation pane on the left, choose Logs. On the Slow Query Logs page, click the Downloads tab. In the log list, 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.
      • When the log is being prepared for download, the log status is Preparing.
      • When the log is ready for download, the log status is Preparation completed.
      • If the preparation for download fails, the log status is Abnormal.

      Logs in the Preparing or Abnormal status cannot be downloaded.

    • 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 redownload the log, click OK.
    • The downloaded log file contains only the logs of the primary node or a read replica.

How Long Is the Delay of RDS for MySQL Slow Query Logs?

In most cases, the delay is 5 minutes. If the size of slow query logs reaches 10 MB within 5 minutes, the logs will be uploaded to OBS in advance. Slow query log statistics cannot be exported.

Parent Topic: Log Management