- 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?
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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
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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?
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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
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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
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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
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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
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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
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Database Connections
- Videos
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Error Code Reference
- Management Console Error Code
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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
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Technical White Paper
- GaussDB(DWS)
- Platforms and Technical Specifications Supported by GaussDB(DWS)
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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
Table Structure Design
Before you optimize a table, you need to understand the structure of the table. During database design, some key factors about table design will greatly affect the subsequent query performance of the database. Table design affects data storage as well. Scientific table design reduces I/O operations and minimizes memory usage, improving the query performance.
This section describes how to optimize table performance in GaussDB(DWS) by properly designing the table structure (for example, by configuring the table storage mode, compression level, distribution mode, distribution column, partitioned tables, and local clustering).
Selecting a Storage Mode
Selecting a model for table storage is the first step of table definition. Select a proper storage model for your service based on the table below.
Generally, if a table contains many columns (called a wide table) and its query involves only a few columns, column storage is recommended. If a table contains only a few columns and a query involves most of the columns, row storage is recommended.
Storage Model |
Application Scenario |
---|---|
Row storage |
Point query (simple index–based query that returns only a few records). Query involving many INSERT, UPDATE, and DELETE operations. |
Column storage |
Statistics analysis query, in which operations, such as group and join, are performed many times. |
The row/column storage of a table is specified by the orientation attribute in the table definition. The value row indicates a row-store table and column indicates a column-store table. The default value is row.
Table Compression
Table compression can be enabled when a table is created. Table compression enables data in the table to be stored in compressed format to reduce memory usage.
In scenarios where I/O is large (much data is read and written) and CPU is sufficient (little data is computed), select a high compression ratio. In scenarios where I/O is small and CPU is insufficient, select a low compression ratio. Based on this principle, you are advised to select different compression ratios and test and compare the results to select the optimal compression ratio as required. Specify a compressions ratio using the COMPRESSION parameter. The supported values are as follows:
- The valid value of column-store tables is YES, NO, LOW, MIDDLE, or HIGH, and the default value is LOW.
- The valid values of row-store tables are YES and NO, and the default is NO. (The row-store table compression function is not put into commercial use. To use this function, contact technical support.)
The service scenarios applicable to each compression level are described in the following table.
Compression Level |
Application Scenario |
---|---|
LOW |
The system CPU usage is high and the disk storage space is sufficient. |
MIDDLE |
The system CPU usage is moderate and the disk storage space is insufficient. |
HIGH |
The system CPU usage is low and the disk storage space is insufficient. |
Selecting a Distribution Mode
GaussDB(DWS) supports the following distribution modes: replication, hash, and Round-robin.
Round-robin is supported in cluster 8.1.2 and later.
Policy |
Description |
Application Scenario |
Advantages/disadvantages |
---|---|---|---|
Replication |
Full data in a table is stored on each DN in the cluster. |
Small tables and dimension tables |
|
Hash |
Table data is distributed on all DNs in the cluster. |
Fact tables containing a large amount of data |
|
Polling (Round-robin) |
Each row in the table is sent to each DN in turn. Data can be evenly distributed on each DN. |
Fact tables that contain a large amount of data and cannot find a proper distribution key in hash mode |
|
Selecting a Distribution Key
If the hash distribution mode is used, a distribution key must be specified for the user table. If a record is inserted, the system performs hash computing based on values in the distribute column and then stores data on the related DN.
Select a hash distribution key based on the following principles:
- The values of the distribution key should be discrete so that data can be evenly distributed on each DN. You can select the primary key of the table as the distribution key. For example, for a person information table, choose the ID number column as the distribution key.
- Do not select the column where a constant filter exists. For example, if a constant constraint (for example, zqdh= '000001') exists on the zqdh column in some queries on the dwcjk table, you are not advised to use zqdh as the distribution key.
- With the above principles met, you can select join conditions as distribution keys, so that join tasks can be pushed down to DNs for execution, reducing the amount of data transferred between the DNs.
For a hash table, an improper distribution key may cause data skew or poor I/O performance on certain DNs. Therefore, you need to check the table to ensure that data is evenly distributed on each DN. You can run the following SQL statements to check for data skew:
1 2 3 4 5
SELECT xc_node_id, count(1) FROM tablename GROUP BY xc_node_id ORDER BY xc_node_id desc;
xc_node_id corresponds to a DN. Generally, over 5% difference between the amount of data on different DNs is regarded as data skew. If the difference is over 10%, choose another distribution key.
- You are not advised to add a column as a distribution key, especially add a new column and use the SEQUENCE value to fill the column. (Sequences may cause performance bottlenecks and unnecessary maintenance costs.)
Using Partitioned Tables
Partitioning refers to splitting what is logically one large table into smaller physical pieces based on specific schemes. The table based on the logic is called a partitioned table, and a physical piece is called a partition. Data is stored on these smaller physical pieces, namely, partitions, instead of the larger logical partitioned table. A partitioned table has the following advantages over an ordinary table:
- High query performance: The system queries only the concerned partitions rather than the whole table, improving the query efficiency.
- High availability: If a partition is faulty, data in the other partitions is still available.
- Easy maintenance: You only need to fix the faulty partition.
The partitioned tables supported by GaussDB(DWS) include range partitioned tables and list partitioned tables. (List partitioned tables are supported only in cluster 8.1.3).
Using Partial Clustering
Partial Cluster Key is the column-based technology. It can minimize or maximize sparse indexes to quickly filter base tables. Partial cluster key can specify multiple columns, but you are advised to specify no more than two columns. Use the following principles to specify columns:
- The selected columns must be restricted by simple expressions in base tables. Such constraints are usually represented by Col, Op, and Const. Col specifies the column name, Op specifies operators, (including =, >, >=, <=, and <) Const specifies constants.
- Select columns that are frequently selected (to filter much more undesired data) in simple expressions.
- List the less frequently selected columns on the top.
- List the columns of the enumerated type at the top.
Selecting a Data type
You can use data types with the following features to improve efficiency:
- Data types that boost execution efficiency
Generally, the calculation of integers (including common comparison calculations, such as =, >, <, ≥, ≤, and ≠ and GROUP BY) is more efficient than that of strings and floating point numbers. For example, if you need to perform a point query on a column-store table whose NUMERIC column is used as a filter criterion, the query will take over 10 seconds. If you change the data type from NUMERIC to INT, the query takes only about 1.8 seconds.
- Selecting data types with a short length
Data types with short length reduce both the data file size and the memory used for computing, improving the I/O and computing performance. For example, use SMALLINT instead of INT, and INT instead of BIGINT.
- Same data type for a join
You are advised to use the same data type for a join. To join columns with different data types, the database needs to convert them to the same type, which leads to additional performance overheads.
Index Use
- The purpose of creating indexes is to accelerate queries. Therefore, ensure that indexes can be used in some queries. If an index is not used by any query statement, the index is meaningless. Delete the index.
- Do not create unnecessary secondary indexes. Useful secondary indexes can accelerate query. However, the space occupied by indexes increases with the number of indexes. Each time an index is added, an additional key-value pair needs to be added when a piece of data is inserted. Therefore, the more indexes, the slower the write speed, and the larger the space usage. In addition, too many indexes affect the optimizer running time, and inappropriate indexes mislead the optimizer. Therefore, the more indexes, the better.
- Create proper indexes based on service characteristics. In principle, indexes need to be created for columns required in a query to improve performance. Indexes can be created in the following scenarios:
- For columns with high differentiation, indexes can significantly reduce the number of rows after filtering. For example, you are advised to create an index in the ID card number column, but not in the gender column.
- If there are multiple query conditions, you can select a combination index. Note that the column of the equivalent condition must be placed before the combination index. For example, if the common query is SELECT * FROM t where c1 = 10 and c2 = 100 and c3 > 10, you can create the combination index Index cidx (c1, c2, c3). In this way, you can use the query conditions to construct an index prefix for scanning.
- When an index column is used as a query condition, do not perform calculation, function, or type conversion on the index column. Otherwise, the optimizer cannot use the index.
- Ensure that the index column contains the query column. Do not always run the SELECT * statement to query all columns.
- The query condition is used. =. When NOT IN is used, indexes cannot be used.
- When LIKE is used, if the condition starts with the wildcard %, the index cannot be used.
- If multiple indexes are available for a query condition but you know which index is the optimal one, you are advised to use the optimizer hint to force the optimizer to use the index. This prevents the optimizer from selecting an incorrect index due to inaccurate statistics or other problems.
- When the IN expression is used as the query condition, the number of matched conditions should not be too large. Otherwise, the execution efficiency is low.
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