What's New
Function Overview
Product Bulletin
- Product Notice
- Version Support Notes
Service Overview
- GaussDB(DWS) Infographics
- What Is GaussDB(DWS)?
- Data Warehouse Types
- Data Warehouse Flavors
- Advantages
- Application Scenarios
- Functions
- Concepts
- Related Services
- Security
- GaussDB(DWS) Permissions Management
- GaussDB(DWS) Access
- Restrictions
- Technical Support
- Service Quotas
- GaussDB(DWS) Technical Specifications
Billing
- GaussDB(DWS) Billing Overview
- Billing Modes
- Item
- Billing Examples
- Billing Mode Change
- Renewal
  - Overview
  - Manual Renewal
- Bills
- Arrears
- Stopping Billing
- Cost Management
- Billing FAQs
Getting Started
- Checkpoint Vehicle Analysis
- Supply Chain Requirement Analysis of a Company
- Operations Status Analysis of a Retail Department Store
- Creating a Time Series Table
- Best Practices of Hot and Cold Data Management
- Best Practices for Automatic Partition Management
- Creating a Cluster and Connecting to It
- Using CDM to Migrate MySQL Data to the GaussDB(DWS) Cluster
- Using DLI Flink Jobs to Write Kafka Data to GaussDB(DWS) in Real Time
- Basic SQL Operations
- Database Quick Start
- Getting Started with Common Practices
User Guide
- Using GaussDB(DWS)
- Preparations
- Creating a GaussDB(DWS) Cluster
- Connecting to a GaussDB(DWS) Cluster
- Creating a GaussDB(DWS) Database and User
- Migrating Service Data to a GaussDB(DWS) Cluster
  - Migrating Data to a GaussDB(DWS) Cluster Using GDS-Kafka
  - Data Source Management
- GaussDB(DWS) Cluster Data Security and Encryption
- GaussDB(DWS) Cluster Management
- GaussDB(DWS) Cluster O&M
Best Practices
- Import and Export
- Data Migration
- Data Analytics
- Decoupled Storage and Compute
  - DWS 3.0 Decoupled Storage and Compute Usage Suggestions and Performance Optimization
- Data Development
- Database Management
- Performance Tuning
  - Optimizing Table Structure Design to Enhance GaussDB(DWS) Query Performance
  - Analyzing SQL Statements That Are Being Executed to Handle GaussDB(DWS) Performance Issues
- Cluster Management
  - Binding Different Resource Pools to Two Types of Jobs to Balance Load for GaussDB(DWS)
  - Scaling Options for GaussDB(DWS) with a Coupled Storage-Compute Architecture
Data Migration and Synchronization
- Data Migration to GaussDB(DWS)
- Importing Data
- Full Database Migration
  - Using CDM to Migrate Data to GaussDB(DWS)
  - Using DSC to Migrate SQL Scripts
- Real-time Import
  - Using DRS to Import Data to GaussDB(DWS)
  - Real-time Data Import From Kafka GaussDB(DWS)
- Metadata Migration
  - Using gs_dump and gs_dumpall to Export Metadata
  - Using gs_restore to Import Data
- Exporting Data
- Other Operations
Developer Guide
- Standard data warehouse (9.1.0.x)
- Standard data warehouse (8.1.3.x)
- Hybrid Data Warehouse (9.1.0.x）
- Hybrid Data Warehouse (8.1.3.x）
- Historical Versions
SQL Syntax Reference
- SQL Syntax Reference (9.1.0.x)
- SQL Syntax Reference (8.1.3.x)
- Historical Versions
Performance Tuning
- Overview of Query Performance Optimization
- Query Execution Process
- SQL Execution Plan
- SQL Optimization Guide
- Optimization Cases
- SQL Execution Troubleshooting
- query_band Load Identification
- Common Performance Parameter Optimization Design
Tool Guide
- Overview
- Downloading Related Tools
- gsql
- Data Studio
- GDS
- DSC
- DataCheck
- DWS-Connector
- Server Tool
API Reference
- Before You Start
- API Overview
- Calling APIs
- Getting Started
- API Description
- Application Cases
  - Using Postman to Call the API for Creating a Cluster
  - Using Postman to Call the API for Creating a Snapshot
- Introduction
- Appendix
SDK Reference
- SDK Overview
FAQs
- Top FAQs
- Product Consulting
- Database Connections
- Data Migration
- Database Usage
- Cluster Management
- Account Permissions
- Database Performance
- Backup and Restoration
  1. Why Does It Take a Long Time to Create an Automated Snapshot in GaussDB(DWS)?
  2. Does a GaussDB(DWS) Snapshot Have the Same Function as an EVS Snapshot?
Troubleshooting
- Database Connections
- JDBC/ODBC
- Data Import and Export
- Database Parameter Modification
- Account/Permission/Password
- Cluster Performance
- Cluster Exceptions
  - The Disk Usage Alarm Is Frequently Generated
- Database Use
Videos
Performance White Paper
- Overview
- Test Result
  - TPC-H Single Query Test
  - TPC-DS Single Query Test
- Test Methods
- Appendixes
  - TPC-H Test Sets
  - TPC-DS Test Sets
Technical White Paper
- GaussDB(DWS)
- Platforms and Technical Specifications Supported by GaussDB(DWS)
  - Technical Specifications
- GaussDB(DWS) Core Technologies
- GaussDB(DWS) Tools
  - Client Tools
  - Database Monitoring Tool
- External APIs
Error Code Reference
- 8.2.0 and earlier versions
  - Management Console Error Code
  - Data Warehouse Service Error Codes
- 8.2.1 or later versions
Glossary
More Documents
- User Guide
- API Reference (ME-Abu Dhabi Region)
- Developer Guide (ME-Abu Dhabi Region)
- SQL Syntax Reference (ME-Abu Dhabi Region)
- Tool Guide (ME-Abu Dhabi Region)
- Error Code Reference (ME-Abu Dhabi Region)
  - Management Console Error Code
- User Guide (Paris Region)
- API Reference (Paris Region)
- Developer Guide (Paris Region)
- SQL Syntax Reference (Paris Region)
- Tool Guide (Paris Region)
- Error Code Reference (Paris Region)
  - Management Console Error Code
- User Guide (Kuala Lumpur Region)
- API Reference (Kuala Lumpur Region)
- Developer Guide (Kuala Lumpur Region)
- SQL Syntax Reference (Kuala Lumpur Region)
- Tool Guide (Kuala Lumpur Region)
- Error Code Reference (Kuala Lumpur Region)
  - Management Console Error Code
General Reference
- Glossary
- Service Level Agreement
- White Papers
- Endpoints
- Permissions

On this page

pg_cancel_backend(pid int)
pg_reload_conf()
pg_rotate_logfile()
pg_terminate_backend(pid int)
pg_wlm_jump_queue(pid int)
gs_wlm_switch_cgroup(pid int, cgroup text)
pg_cancel_query(queryId int)
pgxc_cancel_query(queryId int)
pg_terminate_query(queryId int)
pgxc_terminate_query(queryId int)

Show all

Help Center/ GaussDB(DWS)/ SQL Syntax Reference/ SQL Syntax Reference (9.1.0.x)/ Functions and Operators/ System Administration Functions/ Server Signaling Functions

Server Signaling Functions

Updated on 2024-09-02 GMT+08:00

View PDF

Server signaling functions send control signals to other server processes. Only system administrators can use these functions.

pg_cancel_backend(pid int)

Description: Cancels a current query of the backend.

Return type: boolean

Note: pg_cancel_backend sends a query cancellation signal (SIGINT) to the backend process identified by pid. The PID of an active backend process can be found in the pid column of the pg_stat_activity view, or can be found by listing the database process using ps on the server.

Example:

    
       SELECT pid FROM pg_stat_activity WHERE stmt_type ='RESET';
       pid
-----------------
 281471222065200
(1 row)

SELECT pg_cancel_backend(281471222065200);
 pg_cancel_backend
-------------------
 t
(1 row)

pg_reload_conf()

Description: Notifies the server process to reload the configuration file.

Return type: boolean

Note: pg_reload_conf sends a SIGHUP signal to the server. As a result, all server processes reload their configuration files.

Example:

    
       SELECT pg_reload_conf();
 pg_reload_conf
----------------
 t
(1 row)

pg_rotate_logfile()

Description: Rotates the log files of the server.

Return type: boolean

Note: pg_rotate_logfile instructs the log file manager to immediately switch to a new output file. This function is valid only if the built-in log collector is running.

Example:

    
       SELECT pg_rotate_logfile();
 pg_rotate_logfile
-------------------
 t
(1 row)

pg_terminate_backend(pid int)

Description: Terminates a backend thread.

Return type: boolean

Note: Each of these functions returns true if they are successful and false otherwise.

Example:

    
     
       
       SELECT pid FROM pg_stat_activity;
       pid       
-----------------
 140657876268816
 140433774061312
 140433587902208
 140433656592128
 140433723717376
 140433637189376
 140433552770816
 140433481983744
 140433349310208
(9 rows)

SELECT pg_terminate_backend(140657876268816);
 pg_terminate_backend 
----------------------
 t
(1 row)

      

    
   

pg_wlm_jump_queue(pid int)

Description: Moves a task to the top of the CN queue.

Return type: Boolean

Note: Each of these functions returns true if they are successful and false otherwise.

Example:

    
       SELECT pid FROM pg_stat_activity WHERE stmt_type ='RESET';
       pid
-----------------
 281471222065200
(1 row)

SELECT pg_wlm_jump_queue(281471222065200);
 pg_wlm_jump_queue
-------------------
 t
(1 row)

gs_wlm_switch_cgroup(pid int, cgroup text)

Description: Moves a job to other Cgroup to improve the job priority.

Return type: Boolean

Note: Each of these functions returns true if they are successful and false otherwise.

pg_cancel_query(queryId int)

Description: Cancels a current query of the backend. This function is supported in 8.1.2 or later.

Return type: boolean

Note: pg_cancel_query sends a query cancellation signal (SIGINT) to the backend process identified by query_id. The query_id of an active backend process can be found in the query_id column of the pg_stat_activity view.

Example:

    
       SELECT query_id FROM pgxc_stat_activity WHERE stmt_type ='RESET';
 query_id
----------
        0
        0
(2 rows)

SELECT pg_cancel_query(0);
 pg_cancel_query
-----------------
 f
(1 row)

pgxc_cancel_query(queryId int)

Description: Cancels the query that is being executed in the current cluster. This function is supported in 8.1.2 or later.

Return type: boolean

Note: If the queries of all nodes have been canceled, true is returned. Otherwise, false is returned.

Example:

    
       SELECT query_id FROM pgxc_stat_activity WHERE stmt_type ='RESET';
 query_id
----------
        0
        0
(2 rows)

SELECT pgxc_cancel_query(0);
 pgxc_cancel_query
-------------------
 f
(1 row)

pg_terminate_query(queryId int)

Description: Terminates a current query of the backend. This function is supported in 8.1.2 or later.

Return type: boolean

Example:

    
       SELECT query_id FROM pgxc_stat_activity WHERE stmt_type ='RESET';
 query_id
----------
        0
        0
(2 rows)

SELECT pg_terminate_query(0);
 pg_terminate_query
--------------------
 f
(1 row)

pgxc_terminate_query(queryId int)

Description: Terminates the query that is being executed in the current cluster. This function is supported in 8.1.2 or later.

Return type: boolean

Example:

    
       SELECT query_id FROM pgxc_stat_activity;
    query_id       
-----------------
 72339069014638631
(1 rows)

SELECT pgxc_terminate_query(72339069014638631);
 pgxc_terminate_query 
----------------------
 t
(1 row)