- What's New
- Product Bulletin
- Function Overview
-
Service Overview
- 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
- Pricing Details
- Restrictions
- Service Quotas
- Technical Specifications
- Version Description
-
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
- Before You Start
- Creating and Managing Databases
- Planning a Storage Model
- Creating and Managing Tables
- Loading Sample Data
- Querying System Catalogs
- Creating and Managing Schemas
- Creating and Managing Partitioned Tables
- Creating and Managing Indexes
- Creating and Managing Views
- Creating and Managing Sequences
- Creating and Managing Scheduled Tasks
-
Management Guide
- Process for Using GaussDB(DWS)
- Preparations
- Creating or Deleting a Cluster
-
Cluster Connection
- Methods of Connecting to a Cluster
- Obtaining the Cluster Connection Address
- Using the Data Studio GUI Client to Connect to a Cluster
- Using the gsql CLI Client to Connect to a Cluster
- Using the JDBC and ODBC Drivers to Connect to a Cluster
- Using the Third-Party Function Library psycopg2 of Python to Connect to a Cluster
- Using the Python Library PyGreSQL to Connect to a Cluster
- Managing Database Connections
-
Monitoring and Alarms
- Dashboard
- Databases Monitoring (DMS)
- Monitoring Clusters Using Cloud Eye
-
Alarms
- Alarm Management
- Alarm Rules
- Alarm Subscriptions
-
Alarm Handling
- DWS_2000000001 Node CPU Usage Exceeds the Threshold
- DWS_2000000006 Node Data Disk Usage Exceeds the Threshold
- DWS_2000000009 Node Data Disk I/O Usage Exceeds the Threshold
- DWS_2000000012 Node Data Disk Latency Exceeds the Threshold
- DWS_2000000016 Data Spilled to Disks of the Query Statement Exceeds the Threshold
- DWS_2000000017 Number of Queuing Query Statements Exceeds the Threshold
- DWS_2000000018 Queue Congestion in the Default Cluster Resource Pool
- DWS_2000000020 Long SQL Probe Execution Duration in a Cluster
- DWS_2000000023 A Vacuum Full Operation That Holds a Lock for A Long Time Exists in the Cluster
- Event Notifications
- Specifications Change and Scaling
- Backup and Disaster Recovery
- Intelligent O&M
-
Cluster Management
- Modifying Database Parameters
- Checking the Cluster Status
- Viewing Cluster Details
- Changing a Cluster Name
- O&M Account
- Managing Access Domain Names
- Cluster Topology
- Managing Tags
- Managing Enterprise Projects
- Managing Clusters That Fail to Be Created
- Removing the Read-only Status
- Performing a Primary/Standby Switchback
- Starting and Stopping a Cluster
- Resetting a Password
- Cluster Upgrade
- Associating and Disassociating ELB
- Managing CNs
- Data Integration
- Cluster Log Management
- Database User Management
- Audit Logs
- Cluster Security Management
- Resource Management
- Data Source Management
-
Managing Logical Clusters
- Logical Cluster Overview
- Adding/Deleting a Logical Cluster
- Managing Logical Clusters
- Scheduling GaussDB(DWS) 3.0 Logical Cluster Creation and Deletion
- Tutorial: Converting a Physical Cluster That Contains Data into a Logical Cluster
- Tutorial: Dividing a New Physical Cluster into Logical Clusters
- Tutorial: Setting a Read-Only Logical Cluster and Binding It to a User
-
Best Practices
- Import and Export
-
Data Migration
- Migrating Data From Oracle to GaussDB(DWS)
- Synchronizing MySQL Table Data to GaussDB(DWS) in Real Time
- Using DLI Flink Jobs to Write Kafka Data to GaussDB(DWS) in Real Time
- Practice of Data Interconnection Between Two DWS Clusters Based on GDS
-
Table Optimization Practices
- Table Structure Design
- Table Optimization Overview
- Selecting a Table Model
- Step 1: Creating an Initial Table and Loading Sample Data
- Step 2: Testing System Performance of the Initial Table and Establishing a Baseline
- Step 3: Optimizing a Table
- Step 4: Creating Another Table and Loading Data
- Step 5: Testing System Performance in the New Table
- Step 6: Evaluating the Performance of the Optimized Table
- Appendix: Table Creation Syntax
- Advanced Features
- Database Management
- Sample Data Analysis
- Security Management
-
Data Migration and Synchronization
- Data Migration to GaussDB(DWS)
-
Importing Data
- Importing Data from OBS in Parallel
- Using GDS to Import Data from a Remote Server
- Importing Data from MRS to a Cluster
- Importing Data from One GaussDB(DWS) Cluster to Another
- GDS-based Cross-Cluster Interconnection
- Using a gsql Meta-Command to Import Data
- Running the COPY FROM STDIN Statement to Import Data
- Full Database Migration
- Metadata Migration
- Exporting Data
- Other Operations
-
Developer Guide
-
Standard Data Warehouse (9.1.0.x)
- Before You Start
-
GaussDB(DWS) Development Design Proposal
- Overview
- GaussDB(DWS) Connection Management Specifications
- GaussDB(DWS) Object Design Specifications
- GaussDB(DWS) SQL Statement Development Specifications
- GaussDB(DWS) Stored Procedure Development Specifications
- Detailed Design Rules for GaussDB(DWS) Objects
-
Creating and Managing GaussDB(DWS) Database Objects
- Creating and Managing GaussDB(DWS) Databases
- Creating and Managing GaussDB(DWS) Schemas
- Creating and Managing GaussDB(DWS) Tables
- Selecting a GaussDB(DWS) Table Storage Model
- Creating and Managing GaussDB(DWS) Partitioned Tables
- Creating and Managing GaussDB(DWS) Indexes
- Creating and Using GaussDB(DWS) Sequences
- Creating and Managing GaussDB(DWS) Views
- Creating and Managing GaussDB(DWS) Scheduled Tasks
- Viewing GaussDB(DWS) System Catalogs
- Syntax Compatibility Differences Among Oracle, Teradata, and MySQL
- GaussDB(DWS) Database Security Management
- GaussDB(DWS) Data Query
- GaussDB(DWS) Sorting Rules
- GaussDB(DWS) User-Defined Functions
-
GaussDB(DWS) Stored Procedure
- Overview
- Converting Data Types in GaussDB(DWS) Stored Procedures
- GaussDB(DWS) Stored Procedure Array and Record
- GaussDB(DWS) Stored Procedure Declaration Syntax
- Basic Statements of GaussDB(DWS) Stored Procedures
- Dynamic Statements of GaussDB(DWS) Stored Procedures
- GaussDB(DWS) Stored Procedure Control Statements
- Other Statements in a GaussDB(DWS) Stored Procedure
- GaussDB(DWS) Stored Procedure Cursor
- GaussDB(DWS) Stored Procedure Advanced Package
- GaussDB(DWS) Stored Procedure Debugging
- Using PostGIS Extension
- Using JDBC or ODBC for GaussDB(DWS) Secondary Development
- GaussDB(DWS) Resource Monitoring
-
GaussDB(DWS) Performance Tuning
- Overview
- Performance Diagnosis
- System Optimization
-
SQL Tuning
- SQL Query Execution Process
- SQL Execution Plan
- Execution Plan Operator
- SQL Tuning Process
- Updating Statistics
- Reviewing and Modifying a Table Definition
- Advanced SQL Tuning
- Configuring Optimizer Parameters
- Hint-based Tuning
- Routinely Maintaining Tables
- Routinely Recreating an Index
- Automatic Retry upon SQL Statement Execution Errors
- Query Band Load Identification
-
SQL Tuning Examples
- Case: Selecting an Appropriate Distribution Column
- Case: Creating an Appropriate Index
- Case: Adding NOT NULL for JOIN Columns
- Case: Pushing Down Sort Operations to DNs
- Case: Configuring cost_param for Better Query Performance
- Case: Adjusting the Partial Clustering Key
- Case: Adjusting the Table Storage Mode in a Medium Table
- Case: Reconstructing Partition Tables
- Case: Adjusting the GUC Parameter best_agg_plan
- Case: Rewriting SQL Statements and Eliminating Prune Interference
- Case: Rewriting SQL Statements and Deleting in-clause
- Case: Setting Partial Cluster Keys
- Case: Converting from NOT IN to NOT EXISTS
-
GaussDB(DWS) System Catalogs and Views
- Overview of System Catalogs and System Views
-
System Catalogs
- GS_BLOCKLIST_QUERY
- GS_BLOCKLIST_SQL
- GS_OBSSCANINFO
- GS_RESPOOL_RESOURCE_HISTORY
- GS_WLM_INSTANCE_HISTORY
- GS_WLM_OPERATOR_INFO
- GS_WLM_SESSION_INFO
- GS_WLM_USER_RESOURCE_HISTORY
- PG_AGGREGATE
- PG_AM
- PG_AMOP
- PG_AMPROC
- PG_ATTRDEF
- PG_ATTRIBUTE
- PG_AUTHID
- PG_AUTH_HISTORY
- PG_AUTH_MEMBERS
- PG_BLOCKLISTS
- PG_CAST
- PG_CLASS
- PG_COLLATION
- PG_CONSTRAINT
- PG_CONVERSION
- PG_DATABASE
- PG_DB_ROLE_SETTING
- PG_DEFAULT_ACL
- PG_DEPEND
- PG_DESCRIPTION
- PG_ENUM
- PG_EXCEPT_RULE
- PG_EXTENSION
- PG_EXTENSION_DATA_SOURCE
- PG_FINE_DR_INFO
- PG_FOREIGN_DATA_WRAPPER
- PG_FOREIGN_SERVER
- PG_FOREIGN_TABLE
- PG_INDEX
- PG_INHERITS
- PG_JOB_INFO
- PG_JOBS
- PG_LANGUAGE
- PG_LARGEOBJECT
- PG_LARGEOBJECT_METADATA
- PG_MATVIEW
- PG_NAMESPACE
- PG_OBJECT
- PG_OBSSCANINFO
- PG_OPCLASS
- PG_OPERATOR
- PG_OPFAMILY
- PG_PARTITION
- PG_PLTEMPLATE
- PG_PROC
- PG_PUBLICATION
- PG_PUBLICATION_NAMESPACE
- PG_PUBLICATION_REL
- PG_RANGE
- PG_REDACTION_COLUMN
- PG_REDACTION_POLICY
- PG_RELFILENODE_SIZE
- PG_RLSPOLICY
- PG_RESOURCE_POOL
- PG_REWRITE
- PG_SECLABEL
- PG_SHDEPEND
- PG_SHDESCRIPTION
- PG_SHSECLABEL
- PG_STATISTIC
- PG_STATISTIC_EXT
- PG_STAT_OBJECT
- PG_SUBSCRIPTION
- PG_SYNONYM
- PG_TABLESPACE
- PG_TRIGGER
- PG_TS_CONFIG
- PG_TS_CONFIG_MAP
- PG_TS_DICT
- PG_TS_PARSER
- PG_TS_TEMPLATE
- PG_TYPE
- PG_USER_MAPPING
- PG_USER_STATUS
- PG_WORKLOAD_ACTION
- PGXC_CLASS
- PGXC_GROUP
- PGXC_NODE
- PLAN_TABLE_DATA
- SNAPSHOT
- TABLES_SNAP_TIMESTAMP
- System Catalogs for Performance View Snapshot
-
System Views
- ALL_ALL_TABLES
- ALL_CONSTRAINTS
- ALL_CONS_COLUMNS
- ALL_COL_COMMENTS
- ALL_DEPENDENCIES
- ALL_IND_COLUMNS
- ALL_IND_EXPRESSIONS
- ALL_INDEXES
- ALL_OBJECTS
- ALL_PROCEDURES
- ALL_SEQUENCES
- ALL_SOURCE
- ALL_SYNONYMS
- ALL_TAB_COLUMNS
- ALL_TAB_COMMENTS
- ALL_TABLES
- ALL_USERS
- ALL_VIEWS
- DBA_DATA_FILES
- DBA_USERS
- DBA_COL_COMMENTS
- DBA_CONSTRAINTS
- DBA_CONS_COLUMNS
- DBA_IND_COLUMNS
- DBA_IND_EXPRESSIONS
- DBA_IND_PARTITIONS
- DBA_INDEXES
- DBA_OBJECTS
- DBA_PART_INDEXES
- DBA_PART_TABLES
- DBA_PROCEDURES
- DBA_SEQUENCES
- DBA_SOURCE
- DBA_SYNONYMS
- DBA_TAB_COLUMNS
- DBA_TAB_COMMENTS
- DBA_TAB_PARTITIONS
- DBA_TABLES
- DBA_TABLESPACES
- DBA_TRIGGERS
- DBA_VIEWS
- DUAL
- GET_ALL_TSC_INFO
- GET_TSC_INFO
- GLOBAL_COLUMN_TABLE_IO_STAT
- GLOBAL_REDO_STAT
- GLOBAL_REL_IOSTAT
- GLOBAL_ROW_TABLE_IO_STAT
- GLOBAL_STAT_DATABASE
- GLOBAL_TABLE_CHANGE_STAT
- GLOBAL_TABLE_STAT
- GLOBAL_WORKLOAD_SQL_COUNT
- GLOBAL_WORKLOAD_SQL_ELAPSE_TIME
- GLOBAL_WORKLOAD_TRANSACTION
- GS_ALL_CONTROL_GROUP_INFO
- GS_BLOCKLIST_QUERY
- GS_BLOCKLIST_SQL
- GS_CLUSTER_RESOURCE_INFO
- GS_COLUMN_TABLE_IO_STAT
- GS_OBS_READ_TRAFFIC
- GS_OBS_WRITE_TRAFFIC
- GS_INSTR_UNIQUE_SQL
- GS_NODE_STAT_RESET_TIME
- GS_OBS_LATENCY
- GS_QUERY_MONITOR
- GS_QUERY_RESOURCE_INFO
- GS_REL_IOSTAT
- GS_RESPOOL_RUNTIME_INFO
- GS_RESPOOL_RESOURCE_INFO
- GS_RESPOOL_MONITOR
- GS_ROW_TABLE_IO_STAT
- GS_SESSION_CPU_STATISTICS
- GS_SESSION_MEMORY_STATISTICS
- GS_SQL_COUNT
- GS_STAT_DB_CU
- GS_STAT_SESSION_CU
- GS_TABLE_CHANGE_STAT
- GS_TABLE_STAT
- GS_TOTAL_NODEGROUP_MEMORY_DETAIL
- GS_USER_MONITOR
- GS_USER_TRANSACTION
- GS_VIEW_DEPENDENCY
- GS_VIEW_DEPENDENCY_PATH
- GS_VIEW_INVALID
- GS_WAIT_EVENTS
- GS_WLM_OPERAROR_INFO
- GS_WLM_OPERATOR_HISTORY
- GS_WLM_OPERATOR_STATISTICS
- GS_WLM_SESSION_INFO
- GS_WLM_SESSION_HISTORY
- GS_WLM_SESSION_STATISTICS
- GS_WLM_SQL_ALLOW
- GS_WORKLOAD_SQL_COUNT
- GS_WORKLOAD_SQL_ELAPSE_TIME
- GS_WORKLOAD_TRANSACTION
- MPP_TABLES
- PG_AVAILABLE_EXTENSION_VERSIONS
- PG_AVAILABLE_EXTENSIONS
- PG_BULKLOAD_STATISTICS
- PG_COMM_CLIENT_INFO
- PG_COMM_DELAY
- PG_COMM_STATUS
- PG_COMM_RECV_STREAM
- PG_COMM_SEND_STREAM
- PG_COMM_QUERY_SPEED
- PG_CONTROL_GROUP_CONFIG
- PG_CURSORS
- PG_EXT_STATS
- PG_GET_INVALID_BACKENDS
- PG_GET_SENDERS_CATCHUP_TIME
- PG_GROUP
- PG_INDEXES
- PG_JOB
- PG_JOB_PROC
- PG_JOB_SINGLE
- PG_LIFECYCLE_DATA_DISTRIBUTE
- PG_LOCKS
- PG_LWLOCKS
- PG_NODE_ENV
- PG_OS_THREADS
- PG_POOLER_STATUS
- PG_PREPARED_STATEMENTS
- PG_PREPARED_XACTS
- PG_PUBLICATION_TABLES
- PG_QUERYBAND_ACTION
- PG_REPLICATION_SLOTS
- PG_ROLES
- PG_RULES
- PG_RUNNING_XACTS
- PG_SECLABELS
- PG_SEQUENCES
- PG_SESSION_WLMSTAT
- PG_SESSION_IOSTAT
- PG_SETTINGS
- PG_SHADOW
- PG_SHARED_MEMORY_DETAIL
- PG_STATS
- PG_STAT_ACTIVITY
- PG_STAT_ALL_INDEXES
- PG_STAT_ALL_TABLES
- PG_STAT_BAD_BLOCK
- PG_STAT_BGWRITER
- PG_STAT_DATABASE
- PG_STAT_DATABASE_CONFLICTS
- PG_STAT_GET_MEM_MBYTES_RESERVED
- PG_STAT_USER_FUNCTIONS
- PG_STAT_USER_INDEXES
- PG_STAT_USER_TABLES
- PG_STAT_REPLICATION
- PG_STAT_SYS_INDEXES
- PG_STAT_SYS_TABLES
- PG_STAT_XACT_ALL_TABLES
- PG_STAT_XACT_SYS_TABLES
- PG_STAT_XACT_USER_FUNCTIONS
- PG_STAT_XACT_USER_TABLES
- PG_STATIO_ALL_INDEXES
- PG_STATIO_ALL_SEQUENCES
- PG_STATIO_ALL_TABLES
- PG_STATIO_SYS_INDEXES
- PG_STATIO_SYS_SEQUENCES
- PG_STATIO_SYS_TABLES
- PG_STATIO_USER_INDEXES
- PG_STATIO_USER_SEQUENCES
- PG_STATIO_USER_TABLES
- PG_THREAD_WAIT_STATUS
- PG_TABLES
- PG_TDE_INFO
- PG_TIMEZONE_ABBREVS
- PG_TIMEZONE_NAMES
- PG_TOTAL_MEMORY_DETAIL
- PG_TOTAL_SCHEMA_INFO
- PG_TOTAL_USER_RESOURCE_INFO
- PG_USER
- PG_USER_MAPPINGS
- PG_VIEWS
- PG_WLM_STATISTICS
- PGXC_AIO_RESOURCE_POOL_STATS
- PGXC_BULKLOAD_PROGRESS
- PGXC_BULKLOAD_INFO
- PGXC_BULKLOAD_STATISTICS
- PGXC_COLUMN_TABLE_IO_STAT
- PGXC_COMM_CLIENT_INFO
- PGXC_COMM_DELAY
- PGXC_COMM_RECV_STREAM
- PGXC_COMM_SEND_STREAM
- PGXC_COMM_STATUS
- PGXC_COMM_QUERY_SPEED
- PGXC_DEADLOCK
- PGXC_DISK_CACHE_STATS
- PGXC_DISK_CACHE_ALL_STATS
- PGXC_DISK_CACHE_PATH_INFO
- PGXC_GET_STAT_ALL_TABLES
- PGXC_GET_STAT_ALL_PARTITIONS
- PGXC_GET_TABLE_SKEWNESS
- PGXC_GTM_SNAPSHOT_STATUS
- PGXC_INSTANCE_TIME
- PGXC_LOCKWAIT_DETAIL
- PGXC_INSTR_UNIQUE_SQL
- PGXC_LOCK_CONFLICTS
- PGXC_LWLOCKS
- PGXC_MEMORY_DEBUG_INFO
- PGXC_NODE_ENV
- PGXC_NODE_STAT_RESET_TIME
- PGXC_OBS_IO_SCHEDULER_STATS
- PGXC_OBS_IO_SCHEDULER_PERIODIC_STATS
- PGXC_OS_RUN_INFO
- PGXC_OS_THREADS
- PGXC_POOLER_STATUS
- PGXC_PREPARED_XACTS
- PGXC_REDO_STAT
- PGXC_REL_IOSTAT
- PGXC_REPLICATION_SLOTS
- PGXC_RESPOOL_RUNTIME_INFO
- PGXC_RESPOOL_RESOURCE_INFO
- PGXC_RESPOOL_RESOURCE_HISTORY
- PGXC_ROW_TABLE_IO_STAT
- PGXC_RUNNING_XACTS
- PGXC_SETTINGS
- PGXC_SESSION_WLMSTAT
- PGXC_STAT_ACTIVITY
- PGXC_STAT_BAD_BLOCK
- PGXC_STAT_BGWRITER
- PGXC_STAT_DATABASE
- PGXC_STAT_OBJECT
- PGXC_STAT_REPLICATION
- PGXC_STAT_TABLE_DIRTY
- PGXC_STAT_WAL
- PGXC_SQL_COUNT
- PGXC_TABLE_CHANGE_STAT
- PGXC_TABLE_STAT
- PGXC_THREAD_WAIT_STATUS
- PGXC_TOTAL_MEMORY_DETAIL
- PGXC_TOTAL_SCHEMA_INFO
- PGXC_TOTAL_SCHEMA_INFO_ANALYZE
- PGXC_TOTAL_USER_RESOURCE_INFO
- PGXC_USER_TRANSACTION
- PGXC_VARIABLE_INFO
- PGXC_WAIT_DETAIL
- PGXC_WAIT_EVENTS
- PGXC_WLM_OPERATOR_HISTORY
- PGXC_WLM_OPERATOR_INFO
- PGXC_WLM_OPERATOR_STATISTICS
- PGXC_WLM_SESSION_INFO
- PGXC_WLM_SESSION_HISTORY
- PGXC_WLM_SESSION_STATISTICS
- PGXC_WLM_TABLE_DISTRIBUTION_SKEWNESS
- PGXC_WLM_USER_RESOURCE_HISTORY
- PGXC_WLM_WORKLOAD_RECORDS
- PGXC_WORKLOAD_SQL_COUNT
- PGXC_WORKLOAD_SQL_ELAPSE_TIME
- PGXC_WORKLOAD_TRANSACTION
- PLAN_TABLE
- PV_FILE_STAT
- PV_INSTANCE_TIME
- PV_MATVIEW_DETAIL
- PV_OS_RUN_INFO
- PV_SESSION_MEMORY
- PV_SESSION_MEMORY_DETAIL
- PV_SESSION_STAT
- PV_SESSION_TIME
- PV_TOTAL_MEMORY_DETAIL
- PV_REDO_STAT
- PV_RUNTIME_ATTSTATS
- PV_RUNTIME_RELSTATS
- REDACTION_COLUMNS
- REDACTION_POLICIES
- REMOTE_TABLE_STAT
- SHOW_TSC_INFO
- SHOW_ALL_TSC_INFO
- USER_COL_COMMENTS
- USER_CONSTRAINTS
- USER_CONS_COLUMNS
- USER_INDEXES
- USER_IND_COLUMNS
- USER_IND_EXPRESSIONS
- USER_IND_PARTITIONS
- USER_JOBS
- USER_OBJECTS
- USER_PART_INDEXES
- USER_PART_TABLES
- USER_PROCEDURES
- USER_SEQUENCES
- USER_SOURCE
- USER_SYNONYMS
- USER_TAB_COLUMNS
- USER_TAB_COMMENTS
- USER_TAB_PARTITIONS
- USER_TABLES
- USER_TRIGGERS
- USER_VIEWS
- V$SESSION
- V$SESSION_LONGOPS
-
GUC Parameters of the GaussDB(DWS) Database
- Viewing GUC Parameters
- Configuring GUC Parameters
- GUC Parameter Usage
- Connection and Authentication
- Resource Consumption
- Parallel Data Import
- Write Ahead Logs
- HA Replication
- Query Planning
- Error Reporting and Logging
- Alarm Detection
- Statistics During the Database Running
- Resource Management
- Automatic Cleanup
- Default Settings of Client Connection
- Lock Management
- Version and Platform Compatibility
- Fault Tolerance
- Connection Pool Parameters
- Cluster Transaction Parameters
- Developer Operations
- Auditing
- Transaction Monitoring
- GTM Parameters
- Miscellaneous Parameters
- GaussDB(DWS) Developer Terms
-
Standard Data Warehouse (8.1.3.x)
- Before You Start
-
GaussDB(DWS) Development Design Specifications
- Overview
- GaussDB(DWS) Connection Management Specifications
- GaussDB(DWS) Object Design Specifications
- GaussDB(DWS) SQL Statement Development Specifications
- GaussDB(DWS) Stored Procedure Development Specifications
- Detailed Design Rules for GaussDB(DWS) Objects
-
Creating and Managing GaussDB(DWS) Database Objects
- Creating and Managing GaussDB(DWS) Databases
- Creating and Managing GaussDB(DWS) Schemas
- Selecting a GaussDB(DWS) Table Storage Model
- Creating and Managing GaussDB(DWS) Tables
- Creating and Managing GaussDB(DWS) Partitioned Tables
- Creating and Managing GaussDB(DWS) Indexes
- Creating and Using GaussDB(DWS) Sequences
- Creating and Managing GaussDB(DWS) Views
- Creating and Managing GaussDB(DWS) Scheduled Tasks
- Viewing GaussDB(DWS) System Catalogs
- Syntax Compatibility Differences Among Oracle, Teradata, and MySQL
- GaussDB(DWS) Database Security Management
- GaussDB(DWS) Data Query
- GaussDB(DWS) Sorting Rules
- GaussDB(DWS) User-Defined Functions
-
GaussDB(DWS) Stored Procedure
- Overview
- Converting Data Types in GaussDB(DWS) Stored Procedures
- GaussDB(DWS) Stored Procedure Array and Record
- GaussDB(DWS) Stored Procedure Declaration Syntax
- Basic Statements of GaussDB(DWS) Stored Procedures
- Dynamic Statements of GaussDB(DWS) Stored Procedures
- GaussDB(DWS) Stored Procedure Control Statements
- Other Statements in a GaussDB(DWS) Stored Procedure
- GaussDB(DWS) Stored Procedure Cursor
- GaussDB(DWS) Stored Procedure Advanced Package
- GaussDB(DWS) Stored Procedure Debugging
- Using PostGIS Extension
- Using JDBC or ODBC for GaussDB(DWS) Secondary Development
- GaussDB(DWS) Resource Monitoring
-
GaussDB(DWS) Performance Tuning
- Overview
- Performance Diagnosis
- System Optimization
-
SQL Tuning
- SQL Query Execution Process
- SQL Execution Plan
- Execution Plan Operator
- SQL Tuning Process
- Updating Statistics
- Reviewing and Modifying a Table Definition
- Advanced SQL Tuning
- Hint-based Tuning
- Routinely Maintaining Tables
- Routinely Recreating an Index
- Automatic Retry upon SQL Statement Execution Errors
- query_band Load Identification
-
SQL Tuning Examples
- Case: Selecting an Appropriate Distribution Column
- Case: Creating an Appropriate Index
- Case: Adding NOT NULL for JOIN Columns
- Case: Pushing Down Sort Operations to DNs
- Case: Configuring cost_param for Better Query Performance
- Case: Adjusting the Partial Clustering Key
- Case: Adjusting the Table Storage Mode in a Medium Table
- Case: Reconstructing Partition Tables
- Case: Adjusting the GUC Parameter best_agg_plan
- Case: Rewriting SQL Statements and Eliminating Prune Interference
- Case: Rewriting SQL Statements and Deleting in-clause
- Case: Setting Partial Cluster Keys
- Case: Converting from NOT IN to NOT EXISTS
-
GaussDB(DWS) System Catalogs and Views
- Overview of System Catalogs and System Views
-
System Catalogs
- GS_OBSSCANINFO
- GS_RESPOOL_RESOURCE_HISTORY
- GS_WLM_INSTANCE_HISTORY
- GS_WLM_OPERATOR_INFO
- GS_WLM_SESSION_INFO
- GS_WLM_USER_RESOURCE_HISTORY
- PG_AGGREGATE
- PG_AM
- PG_AMOP
- PG_AMPROC
- PG_ATTRDEF
- PG_ATTRIBUTE
- PG_AUTHID
- PG_AUTH_HISTORY
- PG_AUTH_MEMBERS
- PG_CAST
- PG_CLASS
- PG_COLLATION
- PG_CONSTRAINT
- PG_CONVERSION
- PG_DATABASE
- PG_DB_ROLE_SETTING
- PG_DEFAULT_ACL
- PG_DEPEND
- PG_DESCRIPTION
- PG_ENUM
- PG_EXTENSION
- PG_EXTENSION_DATA_SOURCE
- PG_FOREIGN_DATA_WRAPPER
- PG_FOREIGN_SERVER
- PG_FOREIGN_TABLE
- PG_INDEX
- PG_INHERITS
- PG_JOBS
- PG_LANGUAGE
- PG_LARGEOBJECT
- PG_LARGEOBJECT_METADATA
- PG_NAMESPACE
- PG_OBJECT
- PG_OBSSCANINFO
- PG_OPCLASS
- PG_OPERATOR
- PG_OPFAMILY
- PG_PARTITION
- PG_PLTEMPLATE
- PG_PROC
- PG_RANGE
- PG_REDACTION_COLUMN
- PG_REDACTION_POLICY
- PG_RELFILENODE_SIZE
- PG_RLSPOLICY
- PG_RESOURCE_POOL
- PG_REWRITE
- PG_SECLABEL
- PG_SHDEPEND
- PG_SHDESCRIPTION
- PG_SHSECLABEL
- PG_STATISTIC
- PG_STATISTIC_EXT
- PG_SYNONYM
- PG_TABLESPACE
- PG_TRIGGER
- PG_TS_CONFIG
- PG_TS_CONFIG_MAP
- PG_TS_DICT
- PG_TS_PARSER
- PG_TS_TEMPLATE
- PG_TYPE
- PG_USER_MAPPING
- PG_USER_STATUS
- PG_WORKLOAD_ACTION
- PGXC_CLASS
- PGXC_GROUP
- PGXC_NODE
- PLAN_TABLE_DATA
- SNAPSHOT
- TABLES_SNAP_TIMESTAMP
- System Catalogs for Performance View Snapshot
-
System Views
- ALL_ALL_TABLES
- ALL_CONSTRAINTS
- ALL_CONS_COLUMNS
- ALL_COL_COMMENTS
- ALL_DEPENDENCIES
- ALL_IND_COLUMNS
- ALL_IND_EXPRESSIONS
- ALL_INDEXES
- ALL_OBJECTS
- ALL_PROCEDURES
- ALL_SEQUENCES
- ALL_SOURCE
- ALL_SYNONYMS
- ALL_TAB_COLUMNS
- ALL_TAB_COMMENTS
- ALL_TABLES
- ALL_USERS
- ALL_VIEWS
- DBA_DATA_FILES
- DBA_USERS
- DBA_COL_COMMENTS
- DBA_CONSTRAINTS
- DBA_CONS_COLUMNS
- DBA_IND_COLUMNS
- DBA_IND_EXPRESSIONS
- DBA_IND_PARTITIONS
- DBA_INDEXES
- DBA_OBJECTS
- DBA_PART_INDEXES
- DBA_PART_TABLES
- DBA_PROCEDURES
- DBA_SEQUENCES
- DBA_SOURCE
- DBA_SYNONYMS
- DBA_TAB_COLUMNS
- DBA_TAB_COMMENTS
- DBA_TAB_PARTITIONS
- DBA_TABLES
- DBA_TABLESPACES
- DBA_TRIGGERS
- DBA_VIEWS
- DUAL
- GLOBAL_COLUMN_TABLE_IO_STAT
- GLOBAL_REDO_STAT
- GLOBAL_REL_IOSTAT
- GLOBAL_ROW_TABLE_IO_STAT
- GLOBAL_STAT_DATABASE
- GLOBAL_TABLE_CHANGE_STAT
- GLOBAL_TABLE_STAT
- GLOBAL_WORKLOAD_SQL_COUNT
- GLOBAL_WORKLOAD_SQL_ELAPSE_TIME
- GLOBAL_WORKLOAD_TRANSACTION
- GS_ALL_CONTROL_GROUP_INFO
- GS_CLUSTER_RESOURCE_INFO
- GS_COLUMN_TABLE_IO_STAT
- GS_INSTR_UNIQUE_SQL
- GS_NODE_STAT_RESET_TIME
- GS_REL_IOSTAT
- GS_RESPOOL_RUNTIME_INFO
- GS_RESPOOL_RESOURCE_INFO
- GS_ROW_TABLE_IO_STAT
- GS_SESSION_CPU_STATISTICS
- GS_SESSION_MEMORY_STATISTICS
- GS_SQL_COUNT
- GS_STAT_DB_CU
- GS_STAT_SESSION_CU
- GS_TABLE_CHANGE_STAT
- GS_TABLE_STAT
- GS_TOTAL_NODEGROUP_MEMORY_DETAIL
- GS_USER_TRANSACTION
- GS_VIEW_DEPENDENCY
- GS_VIEW_DEPENDENCY_PATH
- GS_VIEW_INVALID
- GS_WAIT_EVENTS
- GS_WLM_OPERAROR_INFO
- GS_WLM_OPERATOR_HISTORY
- GS_WLM_OPERATOR_STATISTICS
- GS_WLM_SESSION_INFO
- GS_WLM_SESSION_HISTORY
- GS_WLM_SESSION_STATISTICS
- GS_WLM_SQL_ALLOW
- GS_WORKLOAD_SQL_COUNT
- GS_WORKLOAD_SQL_ELAPSE_TIME
- GS_WORKLOAD_TRANSACTION
- MPP_TABLES
- PG_AVAILABLE_EXTENSION_VERSIONS
- PG_AVAILABLE_EXTENSIONS
- PG_BULKLOAD_STATISTICS
- PG_COMM_CLIENT_INFO
- PG_COMM_DELAY
- PG_COMM_STATUS
- PG_COMM_RECV_STREAM
- PG_COMM_SEND_STREAM
- PG_COMM_QUERY_SPEED
- PG_CONTROL_GROUP_CONFIG
- PG_CURSORS
- PG_EXT_STATS
- PG_GET_INVALID_BACKENDS
- PG_GET_SENDERS_CATCHUP_TIME
- PG_GROUP
- PG_INDEXES
- PG_JOB
- PG_JOB_PROC
- PG_JOB_SINGLE
- PG_LIFECYCLE_DATA_DISTRIBUTE
- PG_LOCKS
- PG_NODE_ENV
- PG_OS_THREADS
- PG_POOLER_STATUS
- PG_PREPARED_STATEMENTS
- PG_PREPARED_XACTS
- PG_QUERYBAND_ACTION
- PG_REPLICATION_SLOTS
- PG_ROLES
- PG_RULES
- PG_RUNNING_XACTS
- PG_SECLABELS
- PG_SESSION_WLMSTAT
- PG_SESSION_IOSTAT
- PG_SETTINGS
- PG_SHADOW
- PG_SHARED_MEMORY_DETAIL
- PG_STATS
- PG_STAT_ACTIVITY
- PG_STAT_ALL_INDEXES
- PG_STAT_ALL_TABLES
- PG_STAT_BAD_BLOCK
- PG_STAT_BGWRITER
- PG_STAT_DATABASE
- PG_STAT_DATABASE_CONFLICTS
- PG_STAT_GET_MEM_MBYTES_RESERVED
- PG_STAT_USER_FUNCTIONS
- PG_STAT_USER_INDEXES
- PG_STAT_USER_TABLES
- PG_STAT_REPLICATION
- PG_STAT_SYS_INDEXES
- PG_STAT_SYS_TABLES
- PG_STAT_XACT_ALL_TABLES
- PG_STAT_XACT_SYS_TABLES
- PG_STAT_XACT_USER_FUNCTIONS
- PG_STAT_XACT_USER_TABLES
- PG_STATIO_ALL_INDEXES
- PG_STATIO_ALL_SEQUENCES
- PG_STATIO_ALL_TABLES
- PG_STATIO_SYS_INDEXES
- PG_STATIO_SYS_SEQUENCES
- PG_STATIO_SYS_TABLES
- PG_STATIO_USER_INDEXES
- PG_STATIO_USER_SEQUENCES
- PG_STATIO_USER_TABLES
- PG_THREAD_WAIT_STATUS
- PG_TABLES
- PG_TDE_INFO
- PG_TIMEZONE_ABBREVS
- PG_TIMEZONE_NAMES
- PG_TOTAL_MEMORY_DETAIL
- PG_TOTAL_SCHEMA_INFO
- PG_TOTAL_USER_RESOURCE_INFO
- PG_USER
- PG_USER_MAPPINGS
- PG_VIEWS
- PG_WLM_STATISTICS
- PGXC_BULKLOAD_PROGRESS
- PGXC_BULKLOAD_STATISTICS
- PGXC_COLUMN_TABLE_IO_STAT
- PGXC_COMM_CLIENT_INFO
- PGXC_COMM_DELAY
- PGXC_COMM_RECV_STREAM
- PGXC_COMM_SEND_STREAM
- PGXC_COMM_STATUS
- PGXC_COMM_QUERY_SPEED
- PGXC_DEADLOCK
- PGXC_GET_STAT_ALL_TABLES
- PGXC_GET_STAT_ALL_PARTITIONS
- PGXC_GET_TABLE_SKEWNESS
- PGXC_GTM_SNAPSHOT_STATUS
- PGXC_INSTANCE_TIME
- PGXC_LOCKWAIT_DETAIL
- PGXC_INSTR_UNIQUE_SQL
- PGXC_LOCK_CONFLICTS
- PGXC_NODE_ENV
- PGXC_NODE_STAT_RESET_TIME
- PGXC_OS_RUN_INFO
- PGXC_OS_THREADS
- PGXC_PREPARED_XACTS
- PGXC_REDO_STAT
- PGXC_REL_IOSTAT
- PGXC_REPLICATION_SLOTS
- PGXC_RESPOOL_RUNTIME_INFO
- PGXC_RESPOOL_RESOURCE_INFO
- PGXC_RESPOOL_RESOURCE_HISTORY
- PGXC_ROW_TABLE_IO_STAT
- PGXC_RUNNING_XACTS
- PGXC_SETTINGS
- PGXC_SESSION_WLMSTAT
- PGXC_STAT_ACTIVITY
- PGXC_STAT_BAD_BLOCK
- PGXC_STAT_BGWRITER
- PGXC_STAT_DATABASE
- PGXC_STAT_REPLICATION
- PGXC_STAT_TABLE_DIRTY
- PGXC_SQL_COUNT
- PGXC_TABLE_CHANGE_STAT
- PGXC_TABLE_STAT
- PGXC_THREAD_WAIT_STATUS
- PGXC_TOTAL_MEMORY_DETAIL
- PGXC_TOTAL_SCHEMA_INFO
- PGXC_TOTAL_SCHEMA_INFO_ANALYZE
- PGXC_USER_TRANSACTION
- PGXC_VARIABLE_INFO
- PGXC_WAIT_DETAIL
- PGXC_WAIT_EVENTS
- PGXC_WLM_OPERATOR_HISTORY
- PGXC_WLM_OPERATOR_INFO
- PGXC_WLM_OPERATOR_STATISTICS
- PGXC_WLM_SESSION_INFO
- PGXC_WLM_SESSION_HISTORY
- PGXC_WLM_SESSION_STATISTICS
- PGXC_WLM_WORKLOAD_RECORDS
- PGXC_WORKLOAD_SQL_COUNT
- PGXC_WORKLOAD_SQL_ELAPSE_TIME
- PGXC_WORKLOAD_TRANSACTION
- PLAN_TABLE
- PV_FILE_STAT
- PV_INSTANCE_TIME
- PV_OS_RUN_INFO
- PV_SESSION_MEMORY
- PV_SESSION_MEMORY_DETAIL
- PV_SESSION_STAT
- PV_SESSION_TIME
- PV_TOTAL_MEMORY_DETAIL
- PV_REDO_STAT
- REDACTION_COLUMNS
- REDACTION_POLICIES
- REMOTE_TABLE_STAT
- USER_COL_COMMENTS
- USER_CONSTRAINTS
- USER_CONS_COLUMNS
- USER_INDEXES
- USER_IND_COLUMNS
- USER_IND_EXPRESSIONS
- USER_IND_PARTITIONS
- USER_JOBS
- USER_OBJECTS
- USER_PART_INDEXES
- USER_PART_TABLES
- USER_PROCEDURES
- USER_SEQUENCES
- USER_SOURCE
- USER_SYNONYMS
- USER_TAB_COLUMNS
- USER_TAB_COMMENTS
- USER_TAB_PARTITIONS
- USER_TABLES
- USER_TRIGGERS
- USER_VIEWS
- V$SESSION
- V$SESSION_LONGOPS
-
GUC Parameters of the GaussDB(DWS) Database
- Viewing GUC Parameters
- Configuring GUC Parameters
- GUC Parameter Usage
- Connection and Authentication
- Resource Consumption
- Parallel Data Import
- Write Ahead Logs
- HA Replication
- Query Planning
- Error Reporting and Logging
- Alarm Detection
- Statistics During the Database Running
- Resource Management
- Automatic Cleanup
- Default Settings of Client Connection
- Lock Management
- Version and Platform Compatibility
- Fault Tolerance
- Connection Pool Parameters
- Cluster Transaction Parameters
- Developer Operations
- Auditing
- Transaction Monitoring
- GTM Parameters
- Miscellaneous Parameters
- GaussDB(DWS) Developer Terms
-
Standard Data Warehouse (9.1.0.x)
-
SQL Syntax Reference
-
SQL Syntax Reference (9.1.0.x)
- GaussDB(DWS) SQL Overview
- Differences Between GaussDB(DWS) and PostgreSQL
- Keyword
-
Data Types
- Numeric Types
- Monetary Types
- Boolean Type
- Character Types
- Binary Data Types
- Date/Time Types
- Geometric Types
- Array
- Enumeration Type
- Network Address Types
- Bit String Types
- Text Search Types
- UUID Type
- JSON Types
- RoaringBitmap
- HLL Data Types
- Object Identifier Types
- Pseudo-Types
- Range Types
- Composite Types
- Data Types Supported by Column-Store Tables
- XML
- Constant and Macro
-
Functions and Operators
- Character Processing Functions and Operators
- Binary String Functions and Operators
- Bit String Functions and Operators
- Numeric Functions and Operators
- Date and Time Processing Functions and Operators
- SEQUENCE Functions
- Array Functions and Operators
- Logical Operators
- Comparison Operators
- Pattern Matching Operators
- Aggregate Functions
- Window Functions
- Type Conversion Functions
- JSON/JSONB Functions and Operators
- Security Functions
- Conditional Expression Functions
- Range Functions and Operators
- Data Redaction Functions
- Bitmap Functions and Operators
- UUID Functions
- Text Search Functions and Operators
- HLL Functions and Operators
- Set Returning Functions
- Geometric Functions and Operators
- Network Address Functions and Operators
- System Information Functions
- System Administration Functions
- Backup and Restoration Control Functions
- Database Object Functions
- Residual File Management Functions
- Statistics Information Functions
- Trigger Functions
- XML Functions
- Call Stack Recording Functions
- Hudi System Functions
- Funnel and Retention Functions
- EXTERNAL SCHEMA System Functions
- Storage-Compute Decoupling Functions
- Expressions
- Type Conversion
- Full Text Search
- System Operation
- Transaction Management
-
DDL Syntax
- DDL Syntax Overview
- ALTER BLOCK RULE
- ALTER DATABASE
- ALTER EXCEPT RULE
- ALTER FOREIGN TABLE (GDS Import and Export)
- ALTER FOREIGN TABLE (for HDFS or OBS)
- ALTER FOREIGN TABLE (SQL on other GaussDB(DWS))
- ALTER FUNCTION
- ALTER GROUP
- ALTER INDEX
- ALTER LARGE OBJECT
- ALTER MATERIALIZED VIEW
- ALTER PUBLICATION
- ALTER REDACTION POLICY
- ALTER RESOURCE POOL
- ALTER ROLE
- ALTER SUBSCRIPTION
- ALTER ROW LEVEL SECURITY POLICY
- ALTER SCHEMA
- ALTER SEQUENCE
- ALTER SERVER
- ALTER SESSION
- ALTER SYNONYM
- ALTER SYSTEM KILL SESSION
- ALTER TABLE
- ALTER TABLE PARTITION
- ALTER TEXT SEARCH CONFIGURATION
- ALTER TEXT SEARCH DICTIONARY
- ALTER TRIGGER
- ALTER TYPE
- ALTER USER
- ALTER VIEW
- CLEAN CONNECTION
- CLOSE
- CLUSTER
- COMMENT
- CREATE BARRIER
- CREATE BLOCK RULE
- CREATE DATABASE
- CREATE EXCEPT RULE
- CREATE FOREIGN TABLE (for GDS Import and Export)
- CREATE FOREIGN TABLE (SQL on OBS or Hadoop)
- CREATE FOREIGN TABLE (for OBS Import and Export)
- CREATE FOREIGN TABLE (SQL on other GaussDB(DWS))
- CREATE FUNCTION
- CREATE GROUP
- CREATE INDEX
- CREATE MATERIALIZED VIEW
- CREATE PROCEDURE
- CREATE PUBLICATION
- CREATE REDACTION POLICY
- CREATE ROW LEVEL SECURITY POLICY
- CREATE RESOURCE POOL
- CREATE ROLE
- CREATE SCHEMA
- CREATE SEQUENCE
- CREATE SERVER
- CREATE SUBSCRIPTION
- CREATE SYNONYM
- CREATE TABLE
- CREATE TABLE AS
- CREATE TABLE PARTITION
- CREATE TEXT SEARCH CONFIGURATION
- CREATE TEXT SEARCH DICTIONARY
- CREATE TRIGGER
- CREATE TYPE
- CREATE USER
- CREATE VIEW
- CURSOR
- DISCARD
- DROP BLOCK RULE
- DROP DATABASE
- DROP EXCEPT RULE
- DROP FOREIGN TABLE
- DROP FUNCTION
- DROP GROUP
- DROP INDEX
- DROP MATERIALIZED VIEW
- DROP OWNED
- DROP PUBLICATION
- DROP REDACTION POLICY
- DROP ROW LEVEL SECURITY POLICY
- DROP PROCEDURE
- DROP RESOURCE POOL
- DROP ROLE
- DROP SCHEMA
- DROP SEQUENCE
- DROP SERVER
- DROP SUBSCRIPTION
- DROP SYNONYM
- DROP TABLE
- DROP TEXT SEARCH CONFIGURATION
- DROP TEXT SEARCH DICTIONARY
- DROP TRIGGER
- DROP TYPE
- DROP USER
- DROP VIEW
- FETCH
- MOVE
- REFRESH MATERIALIZED VIEW
- REINDEX
- RENAME TABLE
- RESET
- SET
- SET CONSTRAINTS
- SET ROLE
- SET SESSION AUTHORIZATION
- SHOW
- TRUNCATE
- VACUUM
- DML Syntax
- DCL Syntax
- DQL Syntax
- TCL Syntax
-
SQL Syntax Reference (8.1.3.x)
- GaussDB(DWS) SQL Overview
- Differences Between GaussDB(DWS) and PostgreSQL
- Keyword
-
Data Types
- Numeric Types
- Monetary Types
- Boolean Type
- Character Types
- Binary Data Types
- Date/Time Types
- Geometric Types
- Array
- Enumeration Type
- Network Address Types
- Bit String Types
- Text Search Types
- UUID Type
- JSON Types
- RoaringBitmap
- HLL Data Types
- Object Identifier Types
- Pseudo-Types
- Range Types
- Composite Types
- Data Types Supported by Column-Store Tables
- XML
- Constant and Macro
-
Functions and Operators
- Character Processing Functions and Operators
- Binary String Functions and Operators
- Bit String Functions and Operators
- Mathematical Functions and Operators
- Date and Time Processing Functions and Operators
- SEQUENCE Functions
- Array Functions and Operators
- Logical Operators
- Comparison Operators
- Pattern Matching Operators
- Aggregate Functions
- Window Functions
- Type Conversion Functions
- JSON/JSONB Functions and Operators
- Security Functions
- Conditional Expression Functions
- Range Functions and Operators
- Data Masking Functions
- Roaring Bitmap Functions and Operators
- UUID Functions
- Text Search Functions and Operators
- HLL Functions and Operators
- Set Returning Functions
- Geometric Functions and Operators
- Network Address Functions and Operators
- System Information Functions
- System Administration Functions
- Database Object Functions
- Residual File Management Functions
- Statistics Information Functions
- Trigger Functions
- XML Functions
- Call Stack Recording Functions
- Expressions
- Type Conversion
- Full Text Search
- System Operation
- Transaction Management
-
DDL Syntax
- DDL Syntax Overview
- ALTER DATABASE
- ALTER FOREIGN TABLE (GDS Import and Export)
- ALTER FOREIGN TABLE (for HDFS or OBS)
- ALTER FOREIGN TABLE (SQL on other GaussDB(DWS))
- ALTER FUNCTION
- ALTER GROUP
- ALTER INDEX
- ALTER LARGE OBJECT
- ALTER REDACTION POLICY
- ALTER RESOURCE POOL
- ALTER ROLE
- ALTER ROW LEVEL SECURITY POLICY
- ALTER SCHEMA
- ALTER SEQUENCE
- ALTER SERVER
- ALTER SESSION
- ALTER SYNONYM
- ALTER SYSTEM KILL SESSION
- ALTER TABLE
- ALTER TABLE PARTITION
- ALTER TEXT SEARCH CONFIGURATION
- ALTER TEXT SEARCH DICTIONARY
- ALTER TRIGGER
- ALTER TYPE
- ALTER USER
- ALTER VIEW
- CLEAN CONNECTION
- CLOSE
- CLUSTER
- COMMENT
- CREATE BARRIER
- CREATE DATABASE
- CREATE FOREIGN TABLE (for GDS Import and Export)
- CREATE FOREIGN TABLE (SQL on OBS or Hadoop)
- CREATE FOREIGN TABLE (for OBS Import and Export)
- CREATE FOREIGN TABLE (SQL on other GaussDB(DWS))
- CREATE FUNCTION
- CREATE GROUP
- CREATE INDEX
- CREATE REDACTION POLICY
- CREATE ROW LEVEL SECURITY POLICY
- CREATE PROCEDURE
- CREATE RESOURCE POOL
- CREATE ROLE
- CREATE SCHEMA
- CREATE SEQUENCE
- CREATE SERVER
- CREATE SYNONYM
- CREATE TABLE
- CREATE TABLE AS
- CREATE TABLE PARTITION
- CREATE TEXT SEARCH CONFIGURATION
- CREATE TEXT SEARCH DICTIONARY
- CREATE TRIGGER
- CREATE TYPE
- CREATE USER
- CREATE VIEW
- CURSOR
- DROP DATABASE
- DROP FOREIGN TABLE
- DROP FUNCTION
- DROP GROUP
- DROP INDEX
- DROP OWNED
- DROP REDACTION POLICY
- DROP ROW LEVEL SECURITY POLICY
- DROP PROCEDURE
- DROP RESOURCE POOL
- DROP ROLE
- DROP SCHEMA
- DROP SEQUENCE
- DROP SERVER
- DROP SYNONYM
- DROP TABLE
- DROP TEXT SEARCH CONFIGURATION
- DROP TEXT SEARCH DICTIONARY
- DROP TRIGGER
- DROP TYPE
- DROP USER
- DROP VIEW
- FETCH
- MOVE
- REINDEX
- RENAME TABLE
- RESET
- SET
- SET CONSTRAINTS
- SET ROLE
- SET SESSION AUTHORIZATION
- SHOW
- TRUNCATE
- VACUUM
- DML Syntax
- DCL Syntax
- DQL Syntax
- TCL Syntax
-
SQL Syntax Reference (9.1.0.x)
-
Performance Tuning
- Overview of Query Performance Optimization
- Query Analysis
- Query Improvement
-
Optimization Cases
- Case: Selecting an Appropriate Distribution Column
- Case: Creating an Appropriate Index
- Case: Adding NOT NULL for JOIN Columns
- Case: Pushing Down Sort Operations to DNs
- Case: Configuring cost_param for Better Query Performance
- Case: Adjusting the Distribution Key
- Case: Adjusting the Partial Clustering Key
- Case: Adjusting the Table Storage Mode in a Medium Table
- Case: Adjusting the Local Clustering Column
- Case: Reconstructing Partition Tables
- Case: Adjusting the GUC Parameter best_agg_plan
- Case: Rewriting SQL and Deleting Subqueries (Case 1)
- Case: Rewriting SQL and Deleting Subqueries (Case 2)
- Case: Rewriting SQL Statements and Eliminating Prune Interference
- Case: Rewriting SQL Statements and Deleting in-clause
- Case: Setting Partial Cluster Keys
- SQL Execution Troubleshooting
- query_band Load Identification
-
Tool Guide
- Overview
- Downloading Client Tools
- gsql - CLI Client
-
Data Studio - Integrated Database Development Tool
- About Data Studio
- Installing and Configuring Data Studio
- Quick Start
- Data Studio GUI
- Data Studio Menus
- Data Studio Toolbar
- Data Studio Right-Click Menus
- Connection Profiles
- Databases
- Schemas
- Creating a Function/Procedure
- Editing a Function/Procedure
- Granting/Revoking a Permission (Function/Procedure)
- Debugging a PL/SQL Function
- Working with Functions/Procedures
- GaussDB(DWS) Tables
- Sequences
- Views
- Users/Roles
-
SQL Terminal
- Opening Multiple SQL Terminal Tabs
- Managing the SQL Query Execution History
- Opening and Saving SQL Scripts
- Viewing Object Properties in the SQL Terminal
- Canceling the Execution of SQL Queries
- Formatting of SQL Queries
- Selecting a DB Object in the SQL Terminal
- Viewing the Query Execution Plan and Cost
- Viewing the Query Execution Plan and Cost Graphically
- Working with SQL Terminals
- Exporting Query Results
- Managing SQL Terminal Connections
- Batch Operation
- Personalizing Data Studio
- Performance Specifications
- Security Management
- Troubleshooting
- FAQs
- GDS: Parallel Data Loader
-
DSC: SQL Syntax Migration Tool
- Overview
- Supported Keywords and Features
- Constraints and Limitations
- System Requirements
- Installing DSC
- Configuring DSC
- Using DSC
- Teradata Syntax Migration
-
Oracle Syntax Migration
- Overview
- Schema Objects
- COMPRESS Phrase
- Bitmap Index
- Custom Tablespace
- Supplemental Log Data
- LONG RAW
- SYS_GUID
- DML
- Pseudo Columns
- OUTER JOIN
- OUTER QUERY (+)
- CONNECT BY
- System Functions
- PL/SQL
- PL/SQL Collections (Using User-Defined Types)
- PL/SQL Packages
- VARRAY
- Granting Execution Permissions
- Package Name List
- Data Type
- Chinese Character Support
- Netezza Syntax Migration
- MySQL Syntax Migration
- DB2 Syntax Migration
- Command Reference
- Log Reference
- Troubleshooting
- FAQs
- Security Management
- DWS-Connector
- Server Tool
- API Reference
-
FAQs
-
General Problems
- Why Are Data Warehouses Necessary?
- What Are the Differences Between a Data Warehouse and the Hadoop Big Data Platform?
- Why Should I Use Public Cloud GaussDB(DWS)?
- Should I Choose Public Cloud GaussDB(DWS) or RDS?
- When Should I Use GaussDB(DWS) and MRS?
- What Is the User Quota?
- What Are the Differences Between Users and Roles?
- How Do I Check the Creation Time of a Database User?
- Regions and AZs
- Is My Data Secure in GaussDB(DWS)?
- How Is GaussDB(DWS) Secured?
- Can I Modify the Security Group of a GaussDB(DWS) Cluster?
- How Are LibrA, GaussDB A, and GaussDB(DWS) Related?
- What Is a Database/Data Warehouse/Data Lake/Lakehouse?
-
Cluster Management
- What Do I Do If Creating a GaussDB(DWS) Cluster Failed?
- How Can I Clear and Reclaim the Storage Space?
- Can I Switch My Cluster Nodes to Another Region After Purchase?
- Why Did the Used Storage Shrink After Scale-out?
- How Do I View Node Metrics (CPU, Memory, and Disk Usage)?
- Does GaussDB(DWS) Support BMS?
- How Is the Disk Space or Capacity of GaussDB(DWS) Calculated?
- What Are the gaussdb and postgres Databases of GaussDB(DWS)?
- How Do I Set the Maximum Number of Sessions When Adding an Alarm Rule on Cloud Eye?
- What Should I Do If the Scale-out Check Fails?
- When Should I Add CNs or Scale out a cluster?
- What Are the Scenarios of Resizing a Cluster, Changing the Node Flavor, Scale-out, and Scale-in?
- How Should I Select from a Small-Flavor Many-Node Cluster and a Large-Flavor Three-Node Cluster with Same CPU Cores and Memory?
- What Are the Differences Between Cloud SSDs and Local SSDs?
- What Are the Differences Between Hot Data Storage and Cold Data Storage?
-
Database Connections
- How Applications Communicate with GaussDB(DWS)?
- Does GaussDB(DWS) Support Third-Party Clients and JDBC and ODBC Drivers?
- Can I Connect to GaussDB(DWS) Cluster Nodes Using SSH?
- What Should I Do If I Cannot Connect to a Data Warehouse Cluster?
- Why Was I Not Notified of Failure Unbinding the EIP When GaussDB(DWS) Is Connected Over the Internet?
- How Do I Configure a Whitelist to Protect Clusters Available Through a Public IP Address?
-
Data Import and Export
- What Are the Differences Between Data Formats Supported by OBS and GDS Foreign Tables?
- How Do I Import Incremental Data Using an OBS Foreign Table?
- How Can I Import Data to GaussDB(DWS)?
- How Much Service Data Can a Data Warehouse Store?
- How Do I Use \Copy to Import and Export Data?
- How Do I Implement Fault Tolerance Import Between Different Encoding Libraries
- Can I Import and Export Data to and from OBS Across Regions?
- How Do I Import GaussDB(DWS)/Oracle/MySQL/SQL Server Data to GaussDB(DWS) (Whole Database Migration)?
- Can I Import Data over the Public/External Network Using GDS?
- Which Are the Factors That Affect GaussDB(DWS) Import Performance?
-
Account, Password, and Permissions
- How Does GaussDB(DWS) Implement Workload Isolation?
- How Do I Change the Password of a Database Account When the Password Expires?
- How Do I Grant Table Permissions to a User?
- How Do I Grant Schema Permissions to a User?
- How Do I Create a Database Read-only User?
- How Do I Create Private Database Users and Tables?
- How Do I Revoke the CONNECT ON DATABASE Permission from a User?
- How Do I View the Table Permissions of a User?
- Who Is User Ruby?
-
Database Usage
- How Do I Change Distribution Columns?
- How Do I View and Set the Database Character Encoding?
- What Do I Do If Date Type Is Automatically Converted to the Timestamp Type During Table Creation?
- Do I Need to Run VACUUM FULL and ANALYZE on Common Tables Periodically?
- Do I Need to Set a Distribution Key After Setting a Primary Key?
- Is GaussDB(DWS) Compatible with PostgreSQL Stored Procedures?
- What Are Partitioned Tables, Partitions, and Partition Keys?
- How Can I Export the Table Structure?
- How Can I Delete Table Data Efficiently?
- How Do I View Foreign Table Information?
- If No Distribution Column Is Specified, How Will Data Be Stored?
- How Do I Replace the Null Result with 0?
- How Do I Check Whether a Table Is Row-Stored or Column-Stored?
- How Do I Query the Information About GaussDB(DWS) Column-Store Tables?
- Why Sometimes the GaussDB(DWS) Query Indexes Become Invalid?
- How Do I Use a User-Defined Function to Rewrite the CRC32() Function?
- What Are the Schemas Starting with pg_toast_temp* or pg_temp*?
- Solutions to Inconsistent GaussDB(DWS) Query Results
- Which System Catalogs That the VACUUM FULL Operation Cannot Be Performed on?
- In Which Scenarios Would a Statement Be "idle in transaction"?
- How Does GaussDB(DWS) Implement Row-to-Column and Column-to-Row Conversion?
- What Are the Differences Between Unique Constraints and Unique Indexes?
-
Database Performance
- Why Is SQL Execution Slow After Long GaussDB(DWS) Usage?
- Why Does GaussDB(DWS) Perform Worse Than a Single-Server Database in Extreme Scenarios?
- How Can I View SQL Execution Records in a Certain Period When Read and Write Requests Are Blocked?
- What Do I Do If My Cluster Is Unavailable Because of Insufficient Space?
- What is Operator Spilling in GaussDB(DWS)?
- GaussDB(DWS) CPU Resource Management
- Why the Tasks Executed by an Ordinary User Are Slower Than That Executed by the dbadmin User?
- What Are the Factors Related to the Single-Table Query Performance in GaussDB(DWS)?
- Snapshot Backup and Restoration
-
Billing
- How Do I Renew the Service?
- Is Refund Supported?
- How Am I Billed for Scheduled Synchronization of GaussDB(DWS) Data to a PostgreSQL Database?
- How Can I Try Out GaussDB(DWS) for Free?
- Why Was I Deducted Fees After My GaussDB(DWS) Free Trial Expired?
- Why Can't I See a Cluster After I Subscribe to a Free GaussDB(DWS) Trial?
- How Can I Stop GaussDB(DWS) Billing?
- Does Pay-per-Use Billing Stop When My Cluster Stops?
- Why Is the Purchase Button Unavailable When I Create a Cluster?
- How Do I Unfreeze a Cluster?
- Can I Freeze or Shut Down a GaussDB(DWS) Cluster to Stop Billing?
-
General Problems
-
Troubleshooting
-
Database Connections
- What Do I Do If gsql: command not found Is Displayed When I Run gsql to Connect to the Database?
- Database Cannot Be Connected Using the gsql Client
- An Error Indicating Too Many Client Connections Is Reported When a User Connects to a GaussDB(DWS) Database
- Cluster IP Address Cannot Be Pinged/Accessed
- Error "An I/O error occurred while sending to the backend" Is Reported During Service Execution
- JDBC/ODBC
-
Data Import and Export
- "ERROR: invalid byte sequence for encoding 'UTF8': 0x00" Is Reported When Data Is Imported to GaussDB(DWS) Using COPY FROM
- Data Import and Export Faults with GDS
- Failed to Create a GDS Foreign Table and An Error Is Reported Indicating that ROUNDROBIN Is Not Supported
- When CDM Is Used to Import MySQL Data to GaussDB(DWS), the Column Length Exceeds the Threshold and Data Synchronization Fails
- "Access Denied" Is Displayed When the SQL Statement for Creating an OBS Foreign Table Is Executed
- Disk Usage Increases After Data Fails to Be Imported Using GDS
- Error Message "out of memory" Is Displayed When GDS Is Used to Import Data
- Error Message "connection failure error" Is Displayed During GDS Data Transmission
- Data to Be Imported Contains Chinese When the DataArts Studio Service Is Used to Create a GaussDB(DWS) Foreign Table
- Database Parameter Modification
-
Account/Permission/Password
- How Do I Unlock an Account?
- Account Still Locked After Password Resetting
- After the Permission for Querying Tables in a Schema Is Granted to a User, the User Still Cannot Query the Tables
- How Do I Revoke the Permission of a User If grant select on table t1 to public Has Been Executed on a Table
- An Error Message Is Displayed When a Common User Executes the Statement for Creating or Deleting a GDS or OBS Foreign Table, Indicating that the User Does Not Have the Permission or the Permission Is Insufficient
- After the all Permission Is Granted to the Schema of a User, the Error Message "ERROR: current user does not have privilege to role tom" Persists During Table Creation
- An Error Message Is Reported During Statement Execution, Indicating that the User Does Not Have the Required Permission
- Failed to Run the create extension Command and An Error Indicating No Permission Is Reported
- A User Cannot Be Deleted Due to Its Dependencies
-
Cluster Performance
- Lock Wait Detection
- During SQL Execution, a Table Deadlock Occurs and An Error Stating LOCK_WAIT_TIMEOUT Is Reported
- Error "abort transaction due to concurrent update" Is Reported During SQL Execution
- Solution to High Disk Usage and Cluster Read-Only
- SQL Execution Is Slow with Low Performance and Sometimes Does Not End After a Long Period of Time
- Data Skew Causes Slow SQL Statement Execution and Operations Fail on Large Tables
- Table Size Does not Change After VACUUM FULL Is Executed on the Table
- VACUUM Is Executed After Table Data Deletion, But the Space Is Not Released
- Error LOCK_WAIT_TIMEOUT Is Reported When VACUUM FULL Is Executed
- VACUUM FULL Is Slow
- Table Bloating Causes Slow SQL Query and Failed Data Loading on the GUI
- Memory Overflow Occurs in a Cluster
- Statements with User-defined Functions Cannot Be Pushed Down
- Column-Store Tables Cannot Be Updated or Table Bloat Occurs
- Table Bloat Occurs After Data Is Inserted into a Column-Store Table for Multiple Times
- Writing Data to GaussDB(DWS) Is Slow and Client Data Is Stacked
- Low Query Efficiency
- Poor Query Performance Due to the Lack of Statistics
- Execution of SQL Statements with NOT IN and NOT EXISTS Is Slow Due to Nested Loops in Execution Plans
- SQL Query Is Slow Because Partitions Are Not Pruned
- Optimizer Uses Nested Loop Due to the Small Estimated Number of Rows and the Performance Deteriorates
- SQL Statements Contain the in Constant and No Result Is Returned After SQL Statement Execution
- Performance of Single-Table Point Query Is Poor
- CCN Queuing Under Dynamic Load Management
- Performance Deterioration Due to Data Bloat
- Slow Performance Caused by Too Many Small CUs in Column Storage
- Cluster Exceptions
-
Database Use
- An Error Is Reported When Data Is Inserted or Updated, Indicating that the Distribution Key Cannot Be Updated
- "Connection reset by peer" Is Displayed When a User Executes an SQL Statement
- "value too long for type character varying" Is Displayed When VARCHAR(n) Stores Chinese Characters
- Case Sensitivity in SQL Statements
- cannot drop table test because other objects depend on it Is Displayed When a Table Is Deleted
- Failed to Execute MERGE INTO UPDATE for Multiple Tables
- JDBC Error Occurs Due to session_timeout Settings
- DROP TABLE Fails to Be Executed
- Execution Results of the string_agg Function Are Inconsistent
- Error "could not open relation with OID xxxx" Is Reported During Table Size Query
- DROP TABLE IF EXISTS Syntax Errors
- Different Data Is Displayed for the Same Table Queried By Multiple Users
- When a User Specifies Only an Index Name to Modify the Index, A Message Indicating That the Index Does Not Exist Is Displayed
- An Error Is Reported During SQL Statement Execution, Indicating that the Schema Exists
- Failed to Delete a Database and an Error Is Reported Indicating that a Session Is Connected to the Database
- Byte Type Is Returned After a Table Column of the Character Type Is Read in Java
- "ERROR:start value of partition 'XX' NOT EQUAL up-boundary of last partition." Is Displayed When Operations Related to Table Partitions Are Performed
- Reindexing Fails
- A View Failed to Be Queried
- Global SQL Query
- How Do I Check Whether a Table Has Been Updated or Deleted?
- "Can't fit xid into page" Is Reported
- "unable to get a stable set of rows in the source table" Is Reported
- DWS Metadata Inconsistency - Abnormal Partition Index
- An Error Is Reported When the truncate Command Is Executed on the System Table pg_catalog.gs_wlm_session_info
- "inserted partition key does not map to any table partition" Is Reported When Data Is Inserted into a Partitioned Table
- Error upper boundary of adding partition MUST overtop last existing partition Is Reported When a New Partition Is Added to a Range Partitioned Table
- Error Reported During Table Query: "missing chunk number %d for toast value %u in pg_toast_XXXX"
- When Inserting Data Into a Table, An Error Is Reported: "duplicate key value violates unique constraint "%s""
- Error could not determine which collation to use for string hashing Reported During Service Execution
- When the ODBC Driver of GaussDB(DWS) Is Used, Content of Fields of the Character Type in the SQL Query Result Is Truncated
- Execution Plan Scan Hints Do Not Take Effect
- Error "invalid input syntax for xxx" Is Reported During Data Type Conversion
- Error UNION types %s and %s cannot be matched Is Reported
- "ERROR: Non-deterministic UPDATE" Is Reported During Update
- Error Reported During Data Insertion: null value in column ' %s' violates not-null constraint
- Error "unable to get a stable set of rows in the source table"
- Query Results Are Inconsistent in Oracle, Teradata, and MySQL Compatibility Modes
-
Database Connections
- Videos
-
Error Code Reference
- Management Console Error Code
-
Data Warehouse Service Error Codes
- Description of SQL Error Codes
- Third-Party Library Error Codes
- GAUSS-00001 -- GAUSS-00100
- GAUSS-00101 -- GAUSS-00200
- GAUSS-00201 -- GAUSS-00300
- GAUSS-00301 -- GAUSS-00400
- GAUSS-00401 -- GAUSS-00500
- GAUSS-00501 -- GAUSS-00600
- GAUSS-00601 -- GAUSS-00700
- GAUSS-00701 -- GAUSS-00800
- GAUSS-00801 -- GAUSS-00900
- GAUSS-00901 -- GAUSS-01000
- GAUSS-01001 -- GAUSS-01100
- GAUSS-01101 -- GAUSS-01200
- GAUSS-01201 -- GAUSS-01300
- GAUSS-01301 -- GAUSS-01400
- GAUSS-01401 -- GAUSS-01500
- GAUSS-01501 -- GAUSS-01600
- GAUSS-01601 -- GAUSS-01700
- GAUSS-01701 -- GAUSS-01800
- GAUSS-01801 -- GAUSS-01900
- GAUSS-01901 -- GAUSS-02000
- GAUSS-02001 -- GAUSS-02100
- GAUSS-02101 -- GAUSS-02200
- GAUSS-02201 -- GAUSS-02300
- GAUSS-02301 -- GAUSS-02400
- GAUSS-02401 -- GAUSS-02500
- GAUSS-02501 -- GAUSS-02600
- GAUSS-02601 -- GAUSS-02700
- GAUSS-02701 -- GAUSS-02800
- GAUSS-02801 -- GAUSS-02900
- GAUSS-02901 -- GAUSS-03000
- GAUSS-03001 -- GAUSS-03100
- GAUSS-03101 -- GAUSS-03200
- GAUSS-03201 -- GAUSS-03300
- GAUSS-03301 -- GAUSS-03400
- GAUSS-03401 -- GAUSS-03500
- GAUSS-03501 -- GAUSS-03600
- GAUSS-03601 -- GAUSS-03700
- GAUSS-03701 -- GAUSS-03800
- GAUSS-03801 -- GAUSS-03900
- GAUSS-03901 -- GAUSS-04000
- GAUSS-04001 -- GAUSS-04100
- GAUSS-04101 -- GAUSS-04200
- GAUSS-04201 -- GAUSS-04300
- GAUSS-04301 -- GAUSS-04400
- GAUSS-04401 -- GAUSS-04500
- GAUSS-04501 -- GAUSS-04600
- GAUSS-04601 -- GAUSS-04700
- GAUSS-04701 -- GAUSS-04800
- GAUSS-04901 -- GAUSS-04999
- GAUSS-05101 -- GAUSS-05200
- GAUSS-05201 -- GAUSS-05800
- GAUSS-05801 -- GAUSS-05900
- GAUSS-05901 -- GAUSS-05999
- GAUSS-06101 -- GAUSS-06200
- GAUSS-50000 -- GAUSS-50999
- GAUSS-51000 -- GAUSS-51999
- GAUSS-52000 -- GAUSS-52999
- GAUSS-53000 -- GAUSS-53999
- OE000
-
Technical White Paper
- GaussDB(DWS)
- Platforms and Technical Specifications Supported by GaussDB(DWS)
-
GaussDB(DWS) Core Technologies
- Shared-Nothing Architecture
- Data Distribution in a Distributed System
- Fully Parallel Query
- Vectorized Executor and Hybrid Row-Column Storage Engine
- Resource Monitoring and Management
- Distributed Transactions
- Online Scale-Out
- SQL on Anywhere
- Cluster Management and HA
- SQL Self-Diagnosis
- Transparent Data Encryption
- Data Masking
- Data Backup and Disaster Recovery
- GaussDB(DWS) Tools
- External APIs
CREATE FUNCTION
Function
CREATE FUNCTION defines a new function.
Precautions
- The precision values (if any) of the parameters or return values of a function are not checked.
- When creating a function, you are advised to explicitly specify the schemas of tables in the function definition. Otherwise, the function may fail to be executed.
- current_schema and search_path specified by SET during function creation are invalid. search_path and current_schema before and after function execution should be the same.
- If a function has output parameters, the SELECT statement uses the default values of the output parameters when calling the function. When the CALL statement calls the function, it requires that the output parameter values are adapted to Oracle. When the CALL statement calls an overloaded PACKAGE function, it can use the default values of the output parameters. For details, see examples in CALL.
- Only the functions compatible with PostgreSQL or those with the PACKAGE attribute can be overloaded. After REPLACE is specified, a new function is created instead of replacing a function if the number of parameters, parameter type, or return value is different.
- You can use the SELECT statement to specify different parameters using identical functions, but cannot use the CALL statement to call identical functions without the PACKAGE attribute because CALL aligns with Oracle syntax.
- When you create a function, you cannot insert other agg functions out of the avg function or other functions.
- In non-logical cluster mode, return values, parameters, and variables cannot be set to the tables of the Node Groups that are not installed in the system by default. The internal statements of SQL functions cannot be executed on such tables.
- In logical cluster mode, if return values and parameters of the function are user tables, all the tables must be in the same logical cluster. If the function body involves operations on multiple logical cluster tables, the function cannot be set to IMMUTABLE or SHIPPABLE, preventing the function from being pushed down to a DN.
- In logical cluster mode, the parameters and return values of the function cannot use the %type to reference a table column type. Otherwise, the function will fail to be created.
- By default, the permissions to execute new functions are granted to PUBLIC. For details, see GRANT. You can revoke the default execution permissions from PUBLIC and grant them to other users as needed. To avoid the time window during which new functions can be accessed by all users, create functions in transactions and set function execution permissions.
- In a cluster with multiple CNs, the input or output parameters of a function cannot be set to the temporary table type. This is because the correct temporary schema cannot be obtained based on the table name when the function is created on a non-current CN. As a result, the accurate table type cannot be obtained.
Syntax
- Syntax (compatible with PostgreSQL) for creating a user-defined function:
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CREATE [ OR REPLACE ] FUNCTION function_name ( [ { argname [ argmode ] argtype [ { DEFAULT | := | = } expression ]} [, ...] ] ) [ RETURNS rettype [ DETERMINISTIC ] | RETURNS TABLE ( { column_name column_type } [, ...] )] LANGUAGE lang_name [ {IMMUTABLE | STABLE | VOLATILE } | {SHIPPABLE | NOT SHIPPABLE} | WINDOW | [ NOT ] LEAKPROOF | {CALLED ON NULL INPUT | RETURNS NULL ON NULL INPUT | STRICT } | {[ EXTERNAL ] SECURITY INVOKER | [ EXTERNAL ] SECURITY DEFINER | AUTHID DEFINER | AUTHID CURRENT_USER} | {FENCED | NOT FENCED} | {PACKAGE} | COST execution_cost | ROWS result_rows | SET configuration_parameter { {TO | =} value | FROM CURRENT }} ][...] { AS 'definition' | AS 'obj_file', 'link_symbol' }
- Oracle syntax of creating a customized function:
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CREATE [ OR REPLACE ] FUNCTION function_name ( [ { argname [ argmode ] argtype [ { DEFAULT | := | = } expression ] } [, ...] ] ) RETURN rettype [ DETERMINISTIC ] [ {IMMUTABLE | STABLE | VOLATILE } | {SHIPPABLE | NOT SHIPPABLE} | {PACKAGE} | {FENCED | NOT FENCED} | [ NOT ] LEAKPROOF | {CALLED ON NULL INPUT | RETURNS NULL ON NULL INPUT | STRICT } | {[ EXTERNAL ] SECURITY INVOKER | [ EXTERNAL ] SECURITY DEFINER | AUTHID DEFINER | AUTHID CURRENT_USER } | COST execution_cost | ROWS result_rows | SET configuration_parameter { {TO | =} value | FROM CURRENT ][...] { IS | AS } plsql_body /
Parameter Description
- function_name
Indicates the name of the function to create (optionally schema-qualified).
Value range: a string. It must comply with the naming convention.
NOTE:
If the name of the function to be created is the same as that of a system function, you are advised to specify a schema. When invoking a user-defined function, you need to specify a schema. Otherwise, the system preferentially invokes the system function.
- argname
Indicates the name of a function parameter.
Value range: a string. It must comply with the naming convention.
- argmode
Indicates the mode of a parameter.
Value range: IN, OUT, IN OUT, INOUT, and VARIADIC. The default value is IN. Only the parameter of OUT mode can be followed by VARIADIC. The parameters of OUT and INOUT cannot be used in function definition of RETURNS TABLE.
NOTE:
VARIADIC specifies parameters of array types.
- argtype
Indicates the data types of the function's parameters.
- expression
Indicates the default expression of a parameter.
- rettype
Indicates the return data type.
When there is OUT or IN OUT parameter, the RETURNS clause can be omitted. If the clause exists, it must be the same as the result type indicated by the output parameter. If there are multiple output parameters, the value is RECORD. Otherwise, the value is the same as the type of a single output parameter.
The SETOF modifier indicates that the function will return a set of items, rather than a single item.
- DETERMINISTIC
Adapted to Oracle SQL syntax. You are not advised to use it.
- column_name
Specifies the column name.
- column_type
Specifies the column type.
- definition
Specifies a string constant defining the function; the meaning depends on the language. It can be an internal function name, a path pointing to a target file, a SQL query, or text in a procedural language.
- LANGUAGE lang_name
Indicates the name of the language that is used to implement the function. It can be SQL, internal, or the name of user-defined process language. To ensure downward compatibility, the name can use single quotation marks. Contents in single quotation marks must be capitalized.
- WINDOW
Indicates that the function is a window function. The WINDOW attribute cannot be changed when the function definition is replaced.
NOTICE:
For a user-defined window function, the value of LANGUAGE can only be internal, and the referenced internal function must be a window function.
- IMMUTABLE
Indicates that the function always returns the same result if the parameter values are the same.
If the input argument of the function is a constant, the function value is calculated at the optimizer stage. The advantage is that the expression value can be obtained as early as possible, so the cost estimation is more accurate and the execution plan generated is better.
A user-defined IMMUTABLE function is automatically pushed down to DNs for execution, which may cause potential risks. If a function is defined as IMMUTABLE but the function execution process is in fact not IMMUTABLE, serious problems such as result errors may occur. Therefore, exercise caution when defining the IMMUTABLE attribute for a function.
Examples:
- If a user-defined function references objects such as tables and views, the function cannot be defined as IMMUTABLE, because the function may return different results when the data in a referenced table changes.
- If a user-defined function references a STABLE or VOLATILE function, the function cannot be defined as IMMUTABLE.
- If a user-defined function contains factors that cannot be pushed down, the function cannot be defined as IMMUTABLE, because the IMMUTABLE attribute conflicts with factors that cannot be pushed down. Typical scenarios include functions and syntax that cannot be pushed down.
- If a user-defined function contains an aggregation operation that will generate STREAM plans to complete the operation (meaning that DNs and CNs are involved for results calculation, such as the LISTAGG function), the function cannot be defined as IMMUTABLE.
To prevent possible problems, you can set behavior_compat_options to check_function_conflicts in the database to check definition conflicts. This method can identify the 1 and 2 scenarios described above.
- STABLE
Indicates that the function cannot modify the database, and that within a single table scan it will consistently return the same result for the same parameter values, but that its result varies by SQL statements.
- VOLATILE
Indicates that the function value can change even within a single table scan, so no optimizations can be made.
- SHIPPABLE
NOT SHIPPABLE
Indicates whether the function can be pushed down to DNs for execution.
- Functions of the IMMUTABLE type can always be pushed down to the DNs.
- Functions of the STABLE or VOLATILE type can be pushed down to DNs only if their attribute is SHIPPABLE.
Exercise caution when defining the SHIPPABLE attribute for a function. SHIPPABLE means that the entire function will be pushed down to DNs for execution. If the attribute is incorrectly set, serious problems such as result errors may occur.
Similar to the IMMUTABLE attribute, the SHIPPABLE attribute has use restrictions. The function cannot contain factors that do not allow the function to be pushed down for execution. If a function is pushed down to a single DN for execution, the function's calculation logic will depend only on the data set of the DN.
Examples:
- If a function references a hash table, you cannot define the function as SHIPPABLE.
- If a function contains factors, functions, or syntax that cannot be pushed down, the function cannot be defined as SHIPPABLE. For details, see Optimizing Statement Pushdown.
- If a function's calculation process involves data across DNs, the function cannot be defined as SHIPPABLE. For example, some aggregation operations involve data across DNs.
- PACKAGE
Indicates whether the function can be overloaded. PostgreSQL-style functions can be overloaded, and this parameter is designed for Oracle-style functions.
- All PACKAGE and non-PACKAGE functions cannot be overloaded or replaced.
- PACKAGE functions do not support parameters of the VARIADIC type.
- The PACKAGE attribute of functions cannot be modified.
- LEAKPROOF
Indicates that the function has no side effects. LEAKPROOF can be set only by the system administrator.
- CALLED ON NULL INPUT
Declares that some parameters of the function can be invoked in normal mode if the parameter values are NULL. This parameter can be omitted.
- RETURNS NULL ON NULL INPUT
STRICT
Indicates that the function always returns NULL whenever any of its parameters are NULL. If this parameter is specified, the function is not executed when there are NULL parameters; instead a NULL result is returned automatically.
The usage of RETURNS NULL ON NULL INPUT is the same as that of STRICT.
- EXTERNAL
The keyword EXTERNAL is allowed for SQL conformance, but it is optional since, unlike in SQL, this feature applies to all functions not only external ones.
- SECURITY INVOKER
AUTHID CURRENT_USER
Indicates that the function is to be executed with the permissions of the user that calls it. This parameter can be omitted.
SECURITY INVOKER and AUTHID CURRENT_USER have the same functions.
- SECURITY DEFINER
AUTHID DEFINER
Specifies that the function is to be executed with the permissions of the user that created it.
The usage of AUTHID DEFINER is the same as that of SECURITY DEFINER.
- FENCED
NOT FENCED
(Effective only for C functions) Specifies whether functions are executed in fenced mode. In NOT FENCED mode, a function is executed in a CN or DN process. In FENCED mode, a function is executed in a new fork process, which does not affect CN or DN processes.
Application scenarios:
- Develop or debug a function in FENCED mode and execute it in NOT FENCED mode. This reduces the cost of the fork process and communication.
- Perform complex OS operations, such as open a file, process signals and threads, in FENCED mode so that GaussDB(DWS) running is not affected.
- The default value is FENCED.
- COST execution_cost
A positive number giving the estimated execution cost for the function.
The unit of execution_cost is cpu_operator_cost.
Value range: A positive number.
- ROWS result_rows
Estimates the number of rows returned by the function. This is only allowed when the function is declared to return a set.
Value range: A positive number. The default is 1000 rows.
- configuration_parameter
- value
Sets a specified database session parameter to a specified value. If the value is DEFAULT or RESET, the default setting is used in the new session. OFF closes the setting.
Value range: a string
- DEFAULT
- OFF
- RESET
Specifies the default value.
- from current
Uses the value of configuration_parameter of the current session.
- value
- plsql_body
Indicates the PL/SQL stored procedure body.
NOTICE:
When the function is creating users, the log will record unencrypted passwords. You are not advised to do it.
Examples
Define the function as SQL query.
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CREATE FUNCTION func_add_sql(integer, integer) RETURNS integer AS 'select $1 + $2;' LANGUAGE SQL IMMUTABLE RETURNS NULL ON NULL INPUT; |
Add an integer by parameter name using PL/pgSQL.
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CREATE OR REPLACE FUNCTION func_increment_plsql(i integer) RETURNS integer AS $$ BEGIN RETURN i + 1; END; $$ LANGUAGE plpgsql; |
Return the RECORD type.
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CREATE OR REPLACE FUNCTION compute(i int, out result_1 bigint, out result_2 bigint) returns SETOF RECORD as $$ begin result_1 = i + 1; result_2 = i * 10; return next; end; $$language plpgsql; |
Get a record containing multiple output parameters.
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CREATE FUNCTION func_dup_sql(in int, out f1 int, out f2 text) AS $$ SELECT $1, CAST($1 AS text) || ' is text' $$ LANGUAGE SQL; SELECT * FROM func_dup_sql(42); |
Calculate the sum of two integers and get the result. If the input is null, null will be returned.
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CREATE FUNCTION func_add_sql2(num1 integer, num2 integer) RETURN integer AS BEGIN RETURN num1 + num2; END; / |
Create an overloaded function with the PACKAGE attribute.
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CREATE OR REPLACE FUNCTION package_func_overload(col int, col2 int) return integer package as declare col_type text; begin col := 122; dbms_output.put_line('two int parameters ' || col2); return 0; end; / CREATE OR REPLACE FUNCTION package_func_overload(col int, col2 smallint) return integer package as declare col_type text; begin col := 122; dbms_output.put_line('two smallint parameters ' || col2); return 0; end; / |
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