Diagnose parallel SQL statements

A parallel SQL statement is an SQL statement executed by using parallel scheduling in a tenant. You can use the parallel SQL diagnostics feature to identify SQL statements that do not meet query performance expectations in analytical processing.

You can diagnose parallel SQL statements by using one of the following methods:

• Method 1: Log in to the OceanBase Cloud Platform (OCP) console. In the left-side navigation pane, click OceanBase Autonomy Service. On the page that appears, find the target cluster and click its name to go to the Real-time Diagnostics page.

• Method 2: Log in to the OCP console. On the Overview page of a tenant, click SQL Diagnostics in the left-side navigation pane.

Prerequisites

• To diagnose parallel SQL statements by using Method 1, make sure that you have the following permissions:

  • Resource Permissions: Cluster Read-only or Tenant Read-only permission
  • Menu Permissions: Permission on the Real-time Diagnostics menu of OceanBase Autonomy Service

• To diagnose parallel SQL statements by using Method 2, make sure that you have the following permissions:

  • Resource Permissions: Cluster Read-only or Tenant Read-only permission
  • Menu Permissions: Permission on the SQL Diagnostics menu of Tenants

• You have enabled parameters in the SQL Diagnostics Collection section by referring to Manage parameters.

Procedure

The procedure of Method 1 is described as follows:

1. In the left-side navigation pane, click OceanBase Autonomy Service. On the Cluster Details page, click the name of the target cluster to go to its Real-time Diagnostics page.

2. By default, the SQL Diagnostics tab appears.

   The SQL diagnostic data is not displayed on the SQL Diagnostics tab if you do not set the values of both the cluster parameter enable_sql_audit and the tenant parameter ob_enable_sql_audit to True. You can click Change Cluster Parameters in the prompt to modify the parameter values.

   

3. Click the ParallelSQL tab.

4. Filter the parallel SQL statements.

   1. Specify the filter conditions.

   • Time Range: You can select Last 5 Minutes, Last 10 Minutes, Last 20 Minutes, Last 30 Minutes, Last 1 Hour, Last 3 Hours, or Last 6 Hours from the Time Range drop-down list. You can also select Custom Time from the drop-down list and specify the start time and end time as needed. By default, the information of the last 6 hours is displayed.

   • OBServer: You can select one OBServer node or all OBServer nodes in the list. If you select one OBServer node, only SQL statements executed on the selected OBServer node are queried.

   • Internal SQL: If you select this option, the SQL statements internally initiated in OceanBase Database are displayed in the query result.

   • Keyword: If you specify a keyword, the SQL statements that contain the specified keyword are displayed in the query result. The keywords filter SQL statements in the same way as the SQL LIKE operator. The entered strings are automatically prefixed and suffixed with a percent sign (%).

   • Advanced Search: You can add multiple filter conditions in Advanced Search. Click Add. In the Add Advanced Conditions dialog box, you can specify a metric, an operator, and a metric value. The SQL statements that match the specified conditions are displayed in the query result.

   

   2. Click Search to list all SQL statements that meet the filter conditions.

5. Click Export ParallelSQL to export all SQL statements in the query result.

6. View information about parallel SQL statements.

   1. Click Column Management. In the dialog box that appears, select the columns to display. Then, you can view the selected columns in the parallel SQL statement list.

   

   2. On the ParallelSQL tab, you can view the columns selected. You can copy the SQL text and filter the SQL statements by database. You can also sort the SQL statements by the degree of parallelism, number of executions, total response time, and average response time. You can also view the diagnostic result.

   

   3. You can click the SQL text of an SQL statement to go to the SQL Details page of the statement, where you can view the following details of the SQL statement:

   • In the SQL Text section, you can view the complete SQL statement.

   • In the SQL Execution Profile section, you can view the execution details of the SQL statement at the operator level in the data collection time range. For more information, see the View the execution profile of an SQL statement section in View the details of an SQL statement.

   • On the Previous Tendency tab, you can view the historical trends and plan generation time of the SQL statement. For more information, see the View the historical trends of an SQL statement section in View the details of an SQL statement.

   • On the Execution Plans tab, you can view the execution plans of the SQL statement, or bind an execution plan to the statement. For more information, see the View the execution plans of an SQL statement section in View the details of an SQL statement.

   • On the Index tab, you can view the indexes bound to the SQL statement. For more information, see the View and bind indexes section in View the details of an SQL statement.

   • On the SQL Throttling tab, you can view or set throttling for the SQL statement. For more information, see the Set throttling for the SQL statement section in View the details of an SQL statement.

   • You can view the binding records of the SQL statement in section ① as illustrated on the Execution Plans, Index, and SQL Throttling tabs.

     In the binding records, you can view the status of a bound execution plan, or click Unbind to unbind the plan from the SQL statement. You can click Bind Plan to bind the plan to the SQL statement again.

   

7. Set throttling.

   • You can click Enable Throttling to enable throttling for the SQL statement. For more information, see the Set throttling for the SQL statement section in View the details of an SQL statement.

   • You can also select multiple SQL statements and click Batch Set Throttling. In the dialog box that appears, specify the maximum number of SQL statements that can be executed concurrently.