Category | Description |
Source/Target database type | Source database type: Self-built databases (IDC self-built databases and self-built databases on CVM): SQL Server 2008 R2, 2012, 2014, 2016, 2017, 2019, and 2022. Note: If you need to migrate self-built databases to the cloud, we recommend using the DTS migration feature for greater stability. For operations, see Migration Operation Guide. Third-party vendor SQL Server: 2008 R2, 2012, 2014, 2016, 2017, 2019, and 2022. TencentDB for SQL Server (same-account and cross-account): SQL Server 2008 R2, 2012, 2014, 2016, 2017, 2019, and 2022. Target database type: TencentDB for SQL Server (same-account and cross-account): SQL Server 2008 R2, 2012, 2014, 2016, 2017, 2019, and 2022. |
Synchronization type | Synchronization of structures and full and incremental data is supported. |
Synchronization object | Synchronization of database-level data, table-level (user table) data, database and table structures, primary keys, and indexes is supported. Synchronization of views, storage process, custom functions, custom data types, plan guides, and architectures is supported. Synchronization of triggers is not supported. |
Data type | Supported data types: Unsupported data types: Special types: sql_variant, hierarchyid, geometry, geography. |
Impact on the source database | When Data Transfer Service (DTS) is used to perform data synchronization, it occupies certain resources of the source instance, which may cause the source instance load to increase and add pressure to the database. If your database configuration is low, it is recommended to perform synchronization during off-peak hours. Impacts related to enabling CDC: A brief table lock is caused by enabling CDC since the creation of CDC-related tables and SQL Agent jobs results in certain resource consumption. When CDC is enabled for a long time, note that the incremental data stored by the CDC component is retained for 3 days by default, which may consume a large amount of storage space. It is recommended to use the command exec console.sys.sp_cdc_change_job @job_type = 'cleanup', @retention= <time>; to set the retention time.Enabling CDC for a long time can also impact transaction log truncation. Due to CDC limitations, if the number of tables exceeds 1000 and the number of databases exceeds 10, it is recommended to use the data migration or backup and recovery capability. The default maximum size for a single field that CDC jobs can handle is 64 KB. If any table with CDC enabled contains a single field larger than 64 KB, the command exec sp_configure 'max text repl size', -1; must be used in advance to adjust the source database configurations. |
Impact on the target database | It is recommended not to perform data write operations on the target database when a data synchronization task is executed, as this may affect the progress of the synchronization task and impose the risk of data inconsistency. |
Permission | Source: For specific cloud environment and permission requirements, see Multi-Cloud Environment Support. Target: dbcreator. If both the source and target are Tencent Cloud SQL Server instances, you can ignore this permission requirement. |
Supported SQL statements | DML: INSERT, UPDATE, and DELETE. |
Limitation | The data synchronization feature is not suitable for scenarios with a large volume of DML operations within a short period due to the latency. Foreign key migration is not supported. If tables contain foreign keys, they will not be migrated to the target instance. It is recommended to recreate foreign keys after migration. DDL operations are not supported. Modifying table structures or deleting tables may cause the synchronization task to fail. Structure migration cannot be performed independently, and structure and data are required to be migrated together. Do not modify or delete user information (including usernames, passwords, and permissions) and port numbers in the source and target databases during synchronization, as this may cause the synchronization task to fail. If the source table is large with long-running transactions during the full synchronization phase, it is recommended to enable READ_COMMITTED_SNAPSHOT. Instances with SSL encryption enabled cannot be used as source or target instances for data synchronization. |
Data type | Description | Full synchronization | Incremental synchronization |
tinyint | 1-byte integer (0 - 255) | ✅ | ✅ |
smallint | 2-byte integer (-32,768 to 32,767) | ✅ | ✅ |
int | 4-byte integer (-231 to 231-1) | ✅ | ✅ |
bigint | 8-byte integer (-263 to 263-1) | ✅ | ✅ |
Data type | Description | Full synchronization | Incremental synchronization |
decimal(p,s) | Exact decimal | ✅ | ✅ |
numeric(p,s) | Exact decimal (same as decimal) | ✅ | ✅ |
money | Currency type (8 bytes) | ✅ | ✅ |
smallmoney | Currency type (4 bytes) | ✅ | ✅ |
bit | Boolean type (0/1/NULL) | ✅ | ✅ |
Data type | Description | Full synchronization | Incremental synchronization |
float(n) | floating-point number | ✅ | ✅ |
real | single-precision floating-point number | ✅ | ✅ |
Data type | Description | Full synchronization | Incremental synchronization |
char(n) | Fixed-length non-Unicode string | ✅ | ✅ |
varchar(n) | Variable-length non-Unicode string | ✅ | ✅ |
varchar(max) | Large text (up to 2 GB) | ✅ | ✅ Note: The default maximum size for a single field that CDC jobs can handle is 64 KB. If any table with CDC enabled contains a single field larger than 64 KB, the command exec sp_configure 'max text repl size', -1; must be used in advance to adjust the source database configurations. |
text | Large text | ✅ | ✅ |
nchar(n) | Fixed-length Unicode string | ✅ | ✅ |
nvarchar(n) | Variable-length Unicode string | ✅ | ✅ |
nvarchar(max) | Large Unicode text (up to 2 GB) | ✅ | ✅ Note: The default maximum size for a single field that CDC jobs can handle is 64 KB. If any table with CDC enabled contains a single field larger than 64 KB, the command exec sp_configure 'max text repl size', -1; must be used in advance to adjust the source database configurations. |
ntext | Large Unicode text | ✅ | ✅ |
Data type | Description | Full synchronization | Incremental synchronization |
binary(n) | Fixed-length binary | ✅ | ✅ |
varbinary(n) | Variable-length binary | ✅ | ✅ |
varbinary(max) | Large binary (up to 2 GB) | ✅ | ✅ Note: The default maximum size for a single field that CDC jobs can handle is 64 KB. If any table with CDC enabled contains a single field larger than 64 KB, the command exec sp_configure 'max text repl size', -1; must be used in advance to adjust the source database configurations. |
image | Large binary | ✅ | ✅ Note: The default maximum size for a single field that CDC jobs can handle is 64 KB. If any table with CDC enabled contains a single field larger than 64 KB, the command exec sp_configure 'max text repl size', -1; must be used in advance to adjust the source database configurations. |
Data type | Description | Full synchronization | Incremental synchronization |
date | Date (0001-01-01 to 9999-12 -31) | ✅ | ✅ |
time | Time | ✅ | ✅ |
datetime | Datetime (1753-01-01 to 9999-12-31) | ✅ | ✅ |
datetime2 | High-precision datetime | ✅ | ✅ |
smalldatetime | Small datetime (1900-01-01 to 2079-06-06) | ✅ | ✅ |
datetimeoffset | Datetime with time zone | ✅ | ✅ |
timestamp/ rowversion | Row version control | Skipped with warning | Skipped with warning |
Data type | Description | Full synchronization | Incremental synchronization |
uniqueidentifier | GUID/UUID | ✅ | ✅ |
xml | XML data | ✅ | ✅ |
Data type | Description | Full synchronization | Incremental synchronization |
User-defined Data Type | Alias type based on system types | ✅ | ✅ |
sysadmin permissions are not required.Cloud Environment | CDC Enablement Method | Minimum Permission Requirement |
Self-built SQL Server | EXEC sys.sp_cdc_enable_db | If CDC is not enabled, the minimum permission requirement is sysadmin.If CDC is enabled, the minimum permission requirement is db_owner. |
Third-party cloud vendor | EXEC msdb.dbo.rds_cdc_db | db_owner |
| EXEC sp_rds_cdc_enable_db | db_owner |
Feature Category | Sub-feature or Description | Supported Capability |
Resumable transfer | - | Resumable transfer is partially supported during the full export (it is not supported for structure export or export of tables without primary keys). Resumable transfer is supported for full and incremental imports. |
Synchronization direction | One-to-one | Supported. |
| Many-to-one (multiple instances merged to one/multiple tables merged to one) | Not supported. |
| One-to-many | Not supported. |
| Bidirectional synchronization | Not supported. |
| Synchronization within the same instance (only one-to-one mode is supported) | Not supported. |
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