- Release Notes and Announcements
- Release Notes
- Announcements
- Announcement on the Rule-Based Audit Feature for Database Audit
- Announcement on Some APIs with CAM Authentication Integrated
- Announcement on Some APIs with CAM Authentication Integrated
- Notice on Elimination of Some Indicators in Event Alarms
- Commercial Billing for Database Proxy
- TencentDB for MySQL Audit Upgrade
- Added Authentication APIs
- API Authentication Upgrade
- TencentDB for MySQL API 2.0 Discontinuation
- Monitoring Module Upgrade in Shanghai Region
- Monitoring Metric Optimization
- Network Architecture Upgrade
- Change of APIs for Querying the Specifications of Purchasable Database Instances
- Replacement of Certain Old Database Proxy APIs
- Added Advanced Monitoring Metrics
- Change of Calculation Formula for Memory Utilization
- Monitoring Module Upgrade and Optimization in Guangzhou and Shanghai Regions
- Monitoring Module Upgrade
- Parameter Template and Instance Purchase Process Optimization
- Binlog Will Take up Disk Space
- User Tutorial
- Product Introduction
- Tencent Kernel TXSQL
- Overview
- Kernel Version Release Notes
- Functionality Features
- Performance Features
- Security Features
- Stability Features
- TXRocks Engine
- Purchase Guide
- Billing Overview
- Selection Guide
- Purchase Methods
- Renewal
- Payment Overdue
- Refund
- Pay-as-You-Go to Monthly Subscription
- Instance Adjustment Fee
- Backup Space Billing
- Database Audit Billing Overview
- Commercial Billing and Activity Description for Database Proxy
- Description of the Database Proxy Billing Cycle
- Viewing Bills
- Getting Started
- Database Audit
- MySQL Cluster Edition
- Operation Guide
- Use Limits
- Operation Overview
- Instance Management and Maintenance
- Instance Upgrade
- CPU Elastic Expansion
- Read-Only/Disaster Recovery Instances
- Database Proxy
- Account Management
- Database Management Center (DMC)
- Parameter Configuration
- Network and Security
- Backup and Rollback
- Data Migration
- Monitoring and Alarms
- Operation Logs
- Tag
- Practical Tutorial
- Usage Specifications of TencentDB for MySQL
- Configuring Automatic Application Reconnection
- Impact of Modifying MySQL Source Instance Parameters
- Limits on Automatic Conversion from MyISAM to InnoDB
- Creating VPCs for TencentDB for MySQL
- Enhancing Business Load Capacity with TencentDB for MySQL
- Setting up 2-Region-3-DC Disaster Recovery Architecture
- Improving TencentDB for MySQL Performance with Read/Write Separation
- Migrating Data from InnoDB to RocksDB with DTS
- Building LAMP Stack for Web Application
- Building Drupal Website
- Building All-Scenario High-Availability Architecture
- Calling MySQL APIs in Python
- White Paper
- Troubleshooting
- API Documentation
- History
- Introduction
- API Category
- Data Import APIs
- Rollback APIs
- Parameter APIs
- Making API Requests
- Instance APIs
- StopCpuExpand
- StartCpuExpand
- DescribeCpuExpandStrategy
- AddTimeWindow
- BalanceRoGroupLoad
- CloseWanService
- CreateRoInstanceIp
- DeleteTimeWindow
- DescribeCdbZoneConfig
- DescribeDBFeatures
- DescribeDBInstanceCharset
- DescribeDBInstanceConfig
- DescribeDBInstanceGTID
- DescribeDBInstanceInfo
- DescribeDBInstanceRebootTime
- DescribeDBSwitchRecords
- DescribeRoGroups
- DescribeRoMinScale
- DescribeTagsOfInstanceIds
- DescribeTimeWindow
- IsolateDBInstance
- ModifyAutoRenewFlag
- ModifyDBInstanceName
- ModifyDBInstanceProject
- ModifyDBInstanceVipVport
- ModifyInstanceTag
- ModifyNameOrDescByDpId
- ModifyRoGroupInfo
- ModifyTimeWindow
- OfflineIsolatedInstances
- OpenDBInstanceEncryption
- OpenDBInstanceGTID
- OpenWanService
- ReleaseIsolatedDBInstances
- RenewDBInstance
- RestartDBInstances
- StartReplication
- StopReplication
- SwitchDBInstanceMasterSlave
- SwitchDrInstanceToMaster
- SwitchForUpgrade
- UpgradeDBInstanceEngineVersion
- CreateDBInstance
- CreateDBInstanceHour
- DescribeDBInstances
- UpgradeDBInstance
- DescribeDBZoneConfig
- CreateDeployGroup
- DeleteDeployGroups
- DescribeDeployGroupList
- Database Proxy APIs
- AdjustCdbProxy
- AdjustCdbProxyAddress
- CloseCDBProxy
- CloseCdbProxyAddress
- CreateCdbProxy
- CreateCdbProxyAddress
- DescribeCdbProxyInfo
- DescribeProxyCustomConf
- DescribeProxySupportParam
- ModifyCdbProxyAddressDesc
- ModifyCdbProxyAddressVipAndVPort
- ModifyCdbProxyParam
- ReloadBalanceProxyNode
- SwitchCDBProxy
- UpgradeCDBProxyVersion
- Database Audit APIs
- Security APIs
- Task APIs
- Account APIs
- Backup APIs
- CreateBackup
- DeleteBackup
- DescribeBackupDownloadRestriction
- DescribeBackupOverview
- DescribeBackupSummaries
- DescribeBinlogBackupOverview
- DescribeDataBackupOverview
- DescribeLocalBinlogConfig
- DescribeRemoteBackupConfig
- DescribeSlowLogs
- ModifyBackupDownloadRestriction
- ModifyLocalBinlogConfig
- ModifyRemoteBackupConfig
- DescribeBackups
- DescribeBackupConfig
- DescribeBackupDecryptionKey
- DescribeBackupEncryptionStatus
- DescribeBinlogs
- ModifyBackupConfig
- ModifyBackupEncryptionStatus
- Database APIs
- Monitoring APIs
- Log-related API
- Data Types
- Error Codes
- FAQs
- Service Agreement
- Reference
- Glossary
- Contact Us
- Preset Plugin List
- Release Notes and Announcements
- Release Notes
- Announcements
- Announcement on the Rule-Based Audit Feature for Database Audit
- Announcement on Some APIs with CAM Authentication Integrated
- Announcement on Some APIs with CAM Authentication Integrated
- Notice on Elimination of Some Indicators in Event Alarms
- Commercial Billing for Database Proxy
- TencentDB for MySQL Audit Upgrade
- Added Authentication APIs
- API Authentication Upgrade
- TencentDB for MySQL API 2.0 Discontinuation
- Monitoring Module Upgrade in Shanghai Region
- Monitoring Metric Optimization
- Network Architecture Upgrade
- Change of APIs for Querying the Specifications of Purchasable Database Instances
- Replacement of Certain Old Database Proxy APIs
- Added Advanced Monitoring Metrics
- Change of Calculation Formula for Memory Utilization
- Monitoring Module Upgrade and Optimization in Guangzhou and Shanghai Regions
- Monitoring Module Upgrade
- Parameter Template and Instance Purchase Process Optimization
- Binlog Will Take up Disk Space
- User Tutorial
- Product Introduction
- Tencent Kernel TXSQL
- Overview
- Kernel Version Release Notes
- Functionality Features
- Performance Features
- Security Features
- Stability Features
- TXRocks Engine
- Purchase Guide
- Billing Overview
- Selection Guide
- Purchase Methods
- Renewal
- Payment Overdue
- Refund
- Pay-as-You-Go to Monthly Subscription
- Instance Adjustment Fee
- Backup Space Billing
- Database Audit Billing Overview
- Commercial Billing and Activity Description for Database Proxy
- Description of the Database Proxy Billing Cycle
- Viewing Bills
- Getting Started
- Database Audit
- MySQL Cluster Edition
- Operation Guide
- Use Limits
- Operation Overview
- Instance Management and Maintenance
- Instance Upgrade
- CPU Elastic Expansion
- Read-Only/Disaster Recovery Instances
- Database Proxy
- Account Management
- Database Management Center (DMC)
- Parameter Configuration
- Network and Security
- Backup and Rollback
- Data Migration
- Monitoring and Alarms
- Operation Logs
- Tag
- Practical Tutorial
- Usage Specifications of TencentDB for MySQL
- Configuring Automatic Application Reconnection
- Impact of Modifying MySQL Source Instance Parameters
- Limits on Automatic Conversion from MyISAM to InnoDB
- Creating VPCs for TencentDB for MySQL
- Enhancing Business Load Capacity with TencentDB for MySQL
- Setting up 2-Region-3-DC Disaster Recovery Architecture
- Improving TencentDB for MySQL Performance with Read/Write Separation
- Migrating Data from InnoDB to RocksDB with DTS
- Building LAMP Stack for Web Application
- Building Drupal Website
- Building All-Scenario High-Availability Architecture
- Calling MySQL APIs in Python
- White Paper
- Troubleshooting
- API Documentation
- History
- Introduction
- API Category
- Data Import APIs
- Rollback APIs
- Parameter APIs
- Making API Requests
- Instance APIs
- StopCpuExpand
- StartCpuExpand
- DescribeCpuExpandStrategy
- AddTimeWindow
- BalanceRoGroupLoad
- CloseWanService
- CreateRoInstanceIp
- DeleteTimeWindow
- DescribeCdbZoneConfig
- DescribeDBFeatures
- DescribeDBInstanceCharset
- DescribeDBInstanceConfig
- DescribeDBInstanceGTID
- DescribeDBInstanceInfo
- DescribeDBInstanceRebootTime
- DescribeDBSwitchRecords
- DescribeRoGroups
- DescribeRoMinScale
- DescribeTagsOfInstanceIds
- DescribeTimeWindow
- IsolateDBInstance
- ModifyAutoRenewFlag
- ModifyDBInstanceName
- ModifyDBInstanceProject
- ModifyDBInstanceVipVport
- ModifyInstanceTag
- ModifyNameOrDescByDpId
- ModifyRoGroupInfo
- ModifyTimeWindow
- OfflineIsolatedInstances
- OpenDBInstanceEncryption
- OpenDBInstanceGTID
- OpenWanService
- ReleaseIsolatedDBInstances
- RenewDBInstance
- RestartDBInstances
- StartReplication
- StopReplication
- SwitchDBInstanceMasterSlave
- SwitchDrInstanceToMaster
- SwitchForUpgrade
- UpgradeDBInstanceEngineVersion
- CreateDBInstance
- CreateDBInstanceHour
- DescribeDBInstances
- UpgradeDBInstance
- DescribeDBZoneConfig
- CreateDeployGroup
- DeleteDeployGroups
- DescribeDeployGroupList
- Database Proxy APIs
- AdjustCdbProxy
- AdjustCdbProxyAddress
- CloseCDBProxy
- CloseCdbProxyAddress
- CreateCdbProxy
- CreateCdbProxyAddress
- DescribeCdbProxyInfo
- DescribeProxyCustomConf
- DescribeProxySupportParam
- ModifyCdbProxyAddressDesc
- ModifyCdbProxyAddressVipAndVPort
- ModifyCdbProxyParam
- ReloadBalanceProxyNode
- SwitchCDBProxy
- UpgradeCDBProxyVersion
- Database Audit APIs
- Security APIs
- Task APIs
- Account APIs
- Backup APIs
- CreateBackup
- DeleteBackup
- DescribeBackupDownloadRestriction
- DescribeBackupOverview
- DescribeBackupSummaries
- DescribeBinlogBackupOverview
- DescribeDataBackupOverview
- DescribeLocalBinlogConfig
- DescribeRemoteBackupConfig
- DescribeSlowLogs
- ModifyBackupDownloadRestriction
- ModifyLocalBinlogConfig
- ModifyRemoteBackupConfig
- DescribeBackups
- DescribeBackupConfig
- DescribeBackupDecryptionKey
- DescribeBackupEncryptionStatus
- DescribeBinlogs
- ModifyBackupConfig
- ModifyBackupEncryptionStatus
- Database APIs
- Monitoring APIs
- Log-related API
- Data Types
- Error Codes
- FAQs
- Service Agreement
- Reference
- Glossary
- Contact Us
- Preset Plugin List
Overview
This feature pushes LIMIT/OFFSET and SUM operations down to the storage engine InnoDB when querying single tables, effectively reducing query latency.
When LIMIT/OFFSET is executed using secondary indexes, this feature can avoid using the clustered index values as pointers to find the full table rows, effectively cutting the cost of scanning table data.
This feature pushes SUM operations down to InnoDB. In other words, instead of sending rows to the MySQL server, InnoDB calculates data itself and returns the final result to the MySQL server.
Supported Versions
LIMIT/OFFSET optimization applies to kernel version MySQL 5.7 20180530.
SUM optimization applies to kernel version MySQL 5.7 20180918.
Use Cases
This feature is mainly used to optimize single-table queries with LIMIT/OFFSET or SUM clauses, such as
Select *from tbl Limit 10”, “Select* from tbl Limit 10,2, and Select sum(c1) from tbl.This feature cannot optimize the following queries:
Queries with DISTINCT, GROUP BY, or HAVING clauses
Nested subqueries
Queries with FULLTEXT indexes
Queries with ORDER BY clauses, where the optimizer fails to use indexes to implement ORDER BY
Queries with multi-range read (MRR)
Queries with SQL_CALC_FOUND_ROWS.
Performance Data
Import one million rows of data and test query performance in sysbench:
The execution time of
select * from sbtest1 limit 1000000,1; decreases from 6.3 to 2.8 seconds.The execution time of
select sum(k) from sbtest1; decreases from 5.4 to 1.5 seconds.Instructions
During the execution of an SQL statement, the optimizer automatically modifies the query execution plan to implement computation pushdown according to the following parameters.
Parameters are as follows:
Parameter | Effective Immediately | Type | Default Value | Valid Values/Value Range | Description |
cdb_enable_offset_pushdown | Yes | bool | ON | {ON,OFF} | Enable or disable LIMIT/OFFSET pushdown. It is enabled by default. |
cdb_enable_sumagg_pushdown | Yes | bool | OFF | {ON,OFF} | Enable or disable SUM pushdown. It is disabled by default. |
Note:
Currently, you cannot directly modify the values of the above parameters. If needed, submit a ticket for assistance.
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