Help Center/ GaussDB(for MySQL)/ User Guide/ Logs and Auditing/ Managing Slow Query Logs of a DB Instance
Updated on 2024-09-24 GMT+08:00
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Managing Slow Query Logs of a DB Instance

Scenarios

Slow query logs record statements that exceed long_query_time (10 seconds by default). You can view log details and statistics to identify statements that are executing slowly and optimize the statements.

GaussDB(for MySQL) supports the following statement types:
  • SELECT
  • INSERT
  • UPDATE
  • DELETE
  • CREATE
  • ALTER
  • DROP

Parameter Description

Table 1 Parameters related to slow queries

Parameter

Description

long_query_time

Specifies how many seconds an SQL query has to take to be recorded in slow query logs. The default value is 10s. You are advised to set this parameter to 1s.

The lock wait time is not calculated into the query time.

log_queries_not_using_indexes

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

log_throttle_queries_not_using_indexes

Specifies the SQL statement that can be written to the slow query log every minute. The default value is 0.

Viewing Slow Query Log Details

  1. Log in to the management console.
  2. Click in the upper left corner and select a region and project.
  3. Click in the upper left corner of the page and choose Databases > GaussDB(for MySQL).
  4. On the Instances page, click the instance name.
  5. In the navigation pane, choose Logs.
  6. On the Slow Query Logs page, view the slow query log details.

    You can view slow query logs of different nodes and SQL statement types in a given database.

    Supported SQL statement types include SELECT, INSERT, UPDATE, DELETE, CREATE, ALTER, and DROP.

    You can also view slow query logs in a specified time period by clicking and specifying a time period.

    Figure 1 Viewing slow query logs

Enabling Show Original Log

By default, SQL statements are displayed anonymously. If Show Original Log is enabled, SQL statements in the logs will be displayed in plaintext.

Logs displayed in plaintext will be automatically deleted 30 days later. If a DB instance is deleted, its related logs will also be deleted.

  1. On the Instances page, click the instance name.
  2. In the navigation pane, choose Logs.
  3. On the Slow Query Logs tab, click next to Show Original Log.

    Figure 2 Enabling Show Original Log

  4. In the displayed dialog box, click Yes.

Viewing Statistics

  1. On the Instances page, click the instance name.
  2. In the navigation pane, choose Logs. On the Slow Query Logs tab, click Statistics to view details.

    Figure 3 Statistics

    • 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(N) will be displayed.
    • However, if Show Original Log is enabled, all of the slow SQL statements are displayed. For example, if select sleep(1) and select sleep(2) are executed in sequence, both of them will be displayed.
    • No. and Ratio of SQL Executions indicates 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 statements within a specified period are analyzed.
    • You can filter slow log statistics by 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.

Downloading a Slow Query Log

  1. On the Instances page, click the instance name.
  2. In the navigation pane, choose Logs.
  3. On the Slow Query Logs tab, click Download. Locate a log whose status is Preparation completed and click Download in the Operation column.

    Figure 4 Downloading a slow query log

    • The system automatically loads the download 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 state cannot be downloaded.

    • Only logs no more than 40 MB can be downloaded directly from this page. The time range is calculated from the time you download the logs back to the time when the accumulated file size reaches 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.
    • You can select the logs to be downloaded by node.

Reporting Slow Logs to LTS

  1. On the Instances page, click the instance name.
  2. In the navigation pane, choose Logs.
  3. On the Slow Query Logs page, click next to Report Slow Logs to LTS.
  4. Select an LTS log group and log stream and click OK.

    Figure 5 Reporting slow logs to LTS

APIs

Querying Slow Query Logs

Parent Topic: Logs and Auditing