Query and analyze slow query logs

Limits

• This feature is supported only by Hologres V0.10 and later. You can check the version of your Hologres instance on the instance details page in the Hologres console. If the version of your Hologres instance is earlier than V0.10, submit a ticket to update your instance.
• To ensure system stability and prevent traffic overloads, a maximum of 2,000 slow query logs can be returned each time.
• The maximum time range in which slow query logs can be queried in the HoloWeb console is seven days.

Query slow query logs

1. Log on to the HoloWeb console. In the top navigation bar, click Diagnostics and Optimization.
2. In the left-side navigation pane, click Historical Slow Query.
3. On the Historical Slow Query page, set the parameters that are described in the following table.
   

   Parameter	Description	Limit
   Instance	The name of the instance whose slow query logs you want to query. By default, the connected instance is selected.	N/A
   Database	The name of the database whose slow query logs you want to query.	You can query slow query logs of the specified database, table, or user provided that you have the required permissions. Otherwise, you can query slow query logs only within your account. For more information, see Query and analyze slow query logs.
   Table	The name of the table whose slow query logs you want to query.
   User	The account ID of the user who initiated the query.
   List Limit	The number of slow query logs to be returned.	A maximum of 2,000 slow query logs can be returned each time.
   Running	The execution duration of the query.	By default, Hologres collects the logs of queries that consume more than 1 second.
   Metrics	The dimension from which the query trend is displayed. Valid values: Slow Query and Failed Query.	N/A
   Query	The statement used in the query. You can use the percent sign (%) in the statement to represent all table names.	N/A
   Type	The type of the statement used in the query. The statement types in categories such as DDL and DML are supported.	N/A
   Query ID	The ID of the query.	N/A
   Time	The time range to query.	The maximum time range in which slow query logs can be queried is seven days.

4. After the parameters are set, click Query to view the trend of slow queries or failed queries and the slow query logs that meet the filter conditions. For more information, see View the trend of slow queries or failed queries and the slow query logs that meet the filter conditions.

View the trend of slow queries or failed queries and the slow query logs that meet the filter conditions

• Trend of slow queries or failed queries
  • View the trend of slow queries or failed queries before and after a specific point in time.

    Click a specific point in time in the trend chart to view the trend of slow queries or failed queries within 10 seconds before and after the point in time.

  • View the trend of slow queries or failed queries within a time range.

    Select a time range in the trend chart to view the trend of slow queries or failed queries within the selected time range.

• Slow query logs that meet the filter conditions
  • View the slow query logs that meet the filter conditions.

    The following table describes the default fields.

    Field	Description
    User ID	The account ID of the user who executed the SQL statement.
    Database	The name of the database whose data is queried.
    Type	The type of the SQL statement used in the query.
    Query	The statement used in the query. You can click the statement to view the details of the statement.
    Status	The status of the query. Valid values: Succeeded and Failed.
    Start Time	The start time of the query.
    Duration	The total execution duration of the query, including the optimization duration, the startup duration of the query, and the duration for returning the query result.
    Read Bytes	The number of bytes read by the query.
    Operation	By default, Details is displayed. Click Details to go to the details page of the query. Then, you can view the details of the query, including the basic information, such as the database whose data is queried and the ID of the query, advanced information, total execution duration, and startup duration. You can also optimize the SQL statement. For more information, see Optimize the performance of internal table queries. Click the icon to the right of Details to open a new SQL editor for the query.

  • View other fields.

    If the default fields cannot meet your requirements, click Customize Columns in the upper-right corner of the Queries section. In the dialog box that appears, select more fields to display.

    
  • View the Gantt chart.
    HoloWeb supports Gantt charts. To view the Gantt chart of queries, you can click View Gantt Chart in the upper-right corner of the Queries section. In the dialog box that appears, you can view the execution status of queries that are concurrently executed within a specified time range. This helps you to identify performance bottlenecks of concurrently-executed queries.