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- 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
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- Read-Only/Disaster Recovery Instances
- Database Proxy
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- 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
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- White Paper
- Troubleshooting
- API Documentation
- History
- Introduction
- API Category
- Making API Requests
- Instance APIs
- StopCpuExpand
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- AddTimeWindow
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- CloseWanService
- CreateDBInstance
- CreateDBInstanceHour
- CreateRoInstanceIp
- DeleteTimeWindow
- DescribeCdbZoneConfig
- DescribeDBFeatures
- DescribeDBInstanceCharset
- DescribeDBInstanceConfig
- DescribeDBInstanceGTID
- DescribeDBInstanceInfo
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- DescribeDBSwitchRecords
- DescribeRoGroups
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- DescribeTagsOfInstanceIds
- DescribeTimeWindow
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- AdjustCdbProxy
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- DescribeCdbProxyInfo
- DescribeProxySupportParam
- ModifyCdbProxyAddressDesc
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- ModifyCdbProxyParam
- CloseCDBProxy
- DescribeProxyCustomConf
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- SwitchCDBProxy
- UpgradeCDBProxyVersion
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- DescribeBackupDecryptionKey
- CreateBackup
- DeleteBackup
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- DescribeDataBackupOverview
- DescribeLocalBinlogConfig
- DescribeRemoteBackupConfig
- DescribeSlowLogs
- ModifyBackupDownloadRestriction
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- ModifyLocalBinlogConfig
- ModifyRemoteBackupConfig
- DescribeBackups
- DescribeBackupConfig
- ModifyBackupConfig
- DescribeBinlogs
- Rollback APIs
- Parameter APIs
- 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 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
- 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
- Making API Requests
- Instance APIs
- StopCpuExpand
- StartCpuExpand
- DescribeCpuExpandStrategy
- AddTimeWindow
- BalanceRoGroupLoad
- CloseWanService
- CreateDBInstance
- CreateDBInstanceHour
- CreateRoInstanceIp
- DeleteTimeWindow
- DescribeCdbZoneConfig
- DescribeDBFeatures
- DescribeDBInstanceCharset
- DescribeDBInstanceConfig
- DescribeDBInstanceGTID
- DescribeDBInstanceInfo
- DescribeDBInstanceRebootTime
- DescribeDBSwitchRecords
- DescribeRoGroups
- DescribeRoMinScale
- DescribeTagsOfInstanceIds
- DescribeTimeWindow
- InitDBInstances
- IsolateDBInstance
- ModifyAutoRenewFlag
- ModifyDBInstanceName
- ModifyDBInstanceProject
- ModifyDBInstanceVipVport
- ModifyInstanceTag
- ModifyRoGroupInfo
- ModifyTimeWindow
- OfflineIsolatedInstances
- OpenDBInstanceEncryption
- OpenDBInstanceGTID
- OpenWanService
- ReleaseIsolatedDBInstances
- RenewDBInstance
- RestartDBInstances
- StartReplication
- StopReplication
- SwitchDBInstanceMasterSlave
- SwitchDrInstanceToMaster
- SwitchForUpgrade
- UpgradeDBInstance
- UpgradeDBInstanceEngineVersion
- DescribeDBInstances
- DescribeDBZoneConfig
- CreateDeployGroup
- DeleteDeployGroups
- DescribeDeployGroupList
- ModifyNameOrDescByDpId
- Data Import APIs
- Database Proxy APIs
- AdjustCdbProxy
- AdjustCdbProxyAddress
- CloseCdbProxyAddress
- CreateCdbProxy
- CreateCdbProxyAddress
- DescribeCdbProxyInfo
- DescribeProxySupportParam
- ModifyCdbProxyAddressDesc
- ModifyCdbProxyAddressVipAndVPort
- ModifyCdbProxyParam
- CloseCDBProxy
- DescribeProxyCustomConf
- ReloadBalanceProxyNode
- SwitchCDBProxy
- UpgradeCDBProxyVersion
- Database Audit APIs
- Security APIs
- Task APIs
- Account APIs
- Backup APIs
- DescribeBackupDecryptionKey
- CreateBackup
- DeleteBackup
- DescribeBackupDownloadRestriction
- DescribeBackupEncryptionStatus
- DescribeBackupOverview
- DescribeBackupSummaries
- DescribeBinlogBackupOverview
- DescribeDataBackupOverview
- DescribeLocalBinlogConfig
- DescribeRemoteBackupConfig
- DescribeSlowLogs
- ModifyBackupDownloadRestriction
- ModifyBackupEncryptionStatus
- ModifyLocalBinlogConfig
- ModifyRemoteBackupConfig
- DescribeBackups
- DescribeBackupConfig
- ModifyBackupConfig
- DescribeBinlogs
- Rollback APIs
- Parameter APIs
- Database APIs
- Monitoring APIs
- Log-related API
- Data Types
- Error Codes
- FAQs
- Service Agreement
- Reference
- Glossary
- Contact Us
- Preset Plugin List
Description of the Feature
Second-level Column Modification operations are only recorded in the Data Dictionary Table to log Column Modification Information, avoiding the data copying that was previously necessary for column modification operations. This significantly reduces the time required for Large Table Column Modifications, minimizing the impact on Application Systems and resource consumption.
Supported Versions
Kernel version MySQL 8.0 20230630 and above.
Applicable Scenario
This feature is suitable for modifying columns in Tables with Large Data Volumes.
Test Results
Number of table rows | Modification Duration without using Second-level Column Modification Feature | Modification Duration with Second-level Column Modification Feature |
1 million | 22.9 seconds | 0.01 seconds |
10 Million | 13 minutes and 39.72 seconds | 0.01 seconds |
100 million | 3 hours, 51 minutes, 16.40 seconds | 0.01 seconds |
Use Instructions
Second-level Column Modification Syntax ALTER TABLE add algorithm = instant Clause, column modification can be performed with the following statement:
ALTER TABLE modify_tab_col MODIFY COLUMN c1 BIGINT,ALGORITHM=INSTANT;
Add the parameter cdb_instant_modify_column_enabled to control the Second-level Column Modification feature, which can be set to ON/OFF.
Parameter Name | Status | Type | Default Value | Valid Values/Value Range | Description |
cdb_instant_modify_column_enabled | yes | bool | OFF | ON/OFF | Feature Toggle, determining whether to enable the Second-level Column Modification feature. |
Note:
Users cannot directly modify the parameter values mentioned above. To make changes, submit a ticket.
Second-level Column Modification Restrictions
Support is limited to modifying column types only; changes to the field's nullable, unsigned/signed, charset are not supported, but modifying the default property is allowed.
Only certain type modifications are supported, and only length can be increased. Currently, conversions are only supported between char and varchar, binary and varbinary, and amongst tinyint/smallint/mediumint/int/bigint.
For example:
char(10) → char(100)
char(10) → varchar(100)
varchar(10) → char(100)
varchar(10) → varchar(100)
binary(10) → binary(100)
binary(10) → varbinary(100)
varbinary(10) → binary(100)
varbinary(10) → varbinary(100)
tinyint/smallint/mediumint/int → bigint
tinyint/smallint/mediumint → int
tinyint/smallint → mediumint
tinyint → smallint
Note:
Modifications between char/varchar and binary/varbinary, as well as integer types, are not supported. For example, changing from char to binary, binary to varchar, or reducing the range of integer types, such as from bigint to int or int to smallint, is not allowed.
A single column can only be modified using INSTANT MODIFY COLUMN once, but multiple columns can be modified with it simultaneously.
After a single column is added/modified using INSTANT ADD/MODIFY COLUMN for the first time, any subsequent modifications to that column must be done in a non-instant manner.
INSTANT ADD COLUMNS and INSTANT MODIFY COLUMNS operations must be executed separately. You may first execute INSTANT ADD COLUMNS, then INSTANT MODIFY COLUMNS, or vice versa. You cannot perform INSTANT MODIFY COLUMN on a column that has been added with INSTANT ADD COLUMN.
You cannot modify the column name and column type at the same time. Instead, you can modify the column name first and then column type.
Import/export is not supported.
Encryption and compression are not supported.
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