Real-Time Synchronization

Precautions

The performance indicators provided in this section are for reference only. The actual environment is affected by factors such as the performance of the source or destination database, network bandwidth, data model, and service model.

Specifications

**Table 1** Full synchronization maximum performance
Data Flow	Reference Value of Maximum Performance of Full Synchronization (MB/s)
MySQL as the source	50
Oracle as the source	40
Redis as the source	30
GaussDB as the source	40
PostgreSQL as the source	30
DDM as the source	20
MongoDB as the source	20

There are many factors that affect the DRS migration speed. The current migration speed is the test data when there is no network and database performance bottlenecks and the task specifications are large. The migration speed is for reference only.
When the destination database is Oracle or GaussDB(DWS), the migration speed in the full phase is 30% to 50% lower than that of other types of databases due to the write mechanism of the destination database.
The write performance of the MongoDB database is affected by the number of indexes. The write performance decreases by 5% to 8% when there is one index. The more indexes, the slower the write speed.

Based on the incremental performance of data flow types, there are six types of specifications: micro, small, medium, large, ultra-large, and macro. Table 2 lists the performance upper limit of each specification.

**Table 2** Performance upper limit
Specifications	Reference Value of Maximum Performance of Incremental Synchronization (Rows/Second)
Micro	300
Small	3,000
Medium	7,500
Large	10,000
Ultra-large	20,000
Macro	> 20,000

The performance of each specification is affected by factors such as the networks, source and destination database performance, and latency. The values in the table are for reference only.
DRS measures the performance of different specifications using the full (with flow control disabled) and incremental synchronization tasks as the standard.
The maximum performance (row/second) is measured by the number of transactions synchronized per second. The statement types include BEGIN, COMMIT, DML (INSERT, DELETE, and UPDATE), and DDL. You can view the destination database write frequency (apply_rows_rate) monitoring metric on Cloud Eye.
DRS allows you to upgrade specifications only for single-AZ synchronization tasks. Task specifications cannot be upgraded for dual-AZ tasks or downgraded. For details, see Changing Specifications.
If you want to compare values for a DRS task, select large or higher specifications when creating the DRS task.

Testing Models

Create a full+incremental real-time synchronization task for two RDS for MySQL instances. Table 3 shows the instance configurations.

**Table 3** Instance specifications
Parameter	Source RDS for MySQL instance	Destination RDS for MySQL instance
Flavor	c6.4xlarge.4 (general-enhanced II)	c6.4xlarge.4 (general-enhanced II)
Instance specifications	Ultra-high I/O	Ultra-high I/O
Storage type	16 vCPUs\|64 GB	16 vCPUs\|64 GB
Storage space	300 GB	300 GB
Maximum connections	18,000	18,000
Maximum QPS	3,325	3,325
Maximum IOPS	114,152	114,152

Test model:

The number of test tables is 20.
All test tables have primary keys.
The record size is 1 KB.
Each transaction contains two DML operations and one COMMIT operation. The ratio of INSERT, UPDATE, and DELETE operations is 1:1:1.

Multiple Specifications

DRS real-time synchronization allows you to select specifications for some specified data flow tasks.

**Table 4** Data flow types that support multiple specifications
Synchronization Direction	Data Flow	Multiple Specifications	Specification Upgrade
To the cloud	MySQL->MySQL	Supported	Supported only for single-AZ tasks
To the cloud	MySQL->PostgreSQL	Supported	Supported only for single-AZ tasks
To the cloud	MySQL -> GaussDB Distributed	Supported	Supported only for single-AZ tasks
To the cloud	MySQL -> GaussDB Primary/Standby	Supported	Supported only for single-AZ tasks
To the cloud	MySQL->GaussDB(DWS)	Supported	Supported only for single-AZ tasks
To the cloud	MySQL->GaussDB(for MySQL)	Supported	Supported only for single-AZ tasks
To the cloud	MySQL->MariaDB	Not supported	Not supported
To the cloud	PostgreSQL->PostgreSQL	Supported	Supported only for single-AZ tasks
To the cloud	PostgreSQL->GaussDB(DWS)	Supported	Supported only for single-AZ tasks
To the cloud	PostgreSQL -> GaussDB Primary/Standby	Not supported	Not supported
To the cloud	PostgreSQL -> GaussDB Distributed	Not supported	Not supported
To the cloud	DDM->MySQL	Supported	Supported only for single-AZ tasks
To the cloud	DDM->GaussDB(DWS)	Supported	Supported only for single-AZ tasks
To the cloud	DDM->DDM	Supported	Supported only for single-AZ tasks
To the cloud	Oracle->GaussDB(DWS)	Supported	Supported only for single-AZ tasks
To the cloud	Oracle->PostgreSQL	Supported	Supported only for single-AZ tasks
To the cloud	Oracle->MySQL	Supported	Supported only for single-AZ tasks
To the cloud	Oracle->GaussDB(for MySQL)	Supported	Supported only for single-AZ tasks
To the cloud	Oracle -> GaussDB Primary/Standby	Supported	Supported only for single-AZ tasks
To the cloud	Oracle -> GaussDB Distributed	Supported	Supported only for single-AZ tasks
To the cloud	Oracle->DDM	Supported	Supported only for single-AZ tasks
To the cloud	DB2 for LUW -> GaussDB Primary/Standby	Not supported	Not supported
To the cloud	DB2 for LUW -> GaussDB Distributed	Not supported	Not supported
To the cloud	DB2 for LUW->GaussDB(DWS)	Not supported	Not supported
To the cloud	TiDB->GaussDB(for MySQL)	Not supported	Not supported
To the cloud	Microsoft SQL Server->GaussDB(DWS)	Not supported	Not supported
To the cloud	Microsoft SQL Server -> GaussDB Primary/Standby	Not supported	Not supported
To the cloud	Microsoft SQL Server -> GaussDB Distributed	Not supported	Not supported
To the cloud	Microsoft SQL Server->Microsoft SQL Server	Not supported	Not supported
To the cloud	Microsoft SQL Server->MySQL	Not supported	Not supported
To the cloud	Microsoft SQL Server->GaussDB(for MySQL)	Not supported	Not supported
To the cloud	Microsoft SQL Server->PostgreSQL	Not supported	Not supported
To the cloud	MongoDB->DDS	Supported	Supported only for single-AZ tasks
To the cloud	MariaDB->MariaDB	Supported	Supported only for single-AZ tasks
To the cloud	MariaDB->MySQL	Not supported	Not supported
To the cloud	MariaDB->GaussDB(for MySQL)	Not supported	Not supported
To the cloud	GaussDB(for MySQL)->GaussDB(for MySQL)	Supported	Supported only for single-AZ tasks
To the cloud	Cassandra->GeminiDB Cassandra	Not supported	Not supported
To the cloud	Dynamo->GeminiDB Dynamo	Not supported	Not supported
From the cloud	MySQL->MySQL	Supported	Supported only for single-AZ tasks
From the cloud	MySQL->Kafka	Supported	Supported only for single-AZ tasks
From the cloud	MySQL->CSS/ES	Supported	Supported only for single-AZ tasks
From the cloud	MySQL->Oracle	Supported	Supported only for single-AZ tasks
From the cloud	MySQL->MariaDB	Not supported	Not supported
From the cloud	DDM->MySQL	Supported	Supported only for single-AZ tasks
From the cloud	DDM->Oracle	Supported	Supported only for single-AZ tasks
From the cloud	DDM->Kafka	Supported	Supported only for single-AZ tasks
From the cloud	DDS->MongoDB	Supported	Supported only for single-AZ tasks
From the cloud	DDS->Kafka	Supported	Supported only for single-AZ tasks
From the cloud	PostgreSQL->PostgreSQL	Supported	Supported only for single-AZ tasks
From the cloud	PostgreSQL->Kafka	Supported	Supported only for single-AZ tasks
From the cloud	GaussDB Primary/Standby -> MySQL	Supported	Supported only for single-AZ tasks
From the cloud	GaussDB Primary/Standby -> Oracle	Supported	Supported only for single-AZ tasks
From the cloud	GaussDB Primary/Standby -> Kafka	Supported	Supported only for single-AZ tasks
From the cloud	GaussDB Primary/Standby -> GaussDB(DWS)	Supported	Supported only for single-AZ tasks
From the cloud	GaussDB Primary/Standby -> GaussDB Distributed	Supported	Supported only for single-AZ tasks
From the cloud	GaussDB Primary/Standby -> GaussDB Primary/Standby	Supported	Supported only for single-AZ tasks
From the cloud	GaussDB Distributed -> MySQL	Supported	Supported only for single-AZ tasks
From the cloud	GaussDB Distributed -> Oracle	Supported	Supported only for single-AZ tasks
From the cloud	GaussDB Distributed -> GaussDB(DWS)	Supported	Supported only for single-AZ tasks
From the cloud	GaussDB Distributed -> Kafka	Supported	Supported only for single-AZ tasks
From the cloud	GaussDB Distributed -> GaussDB Distributed	Supported	Supported only for single-AZ tasks
From the cloud	GaussDB Distributed->GaussDB Primary/Standby	Supported	Supported only for single-AZ tasks
From the cloud	GaussDB(for MySQL)->MySQL	Supported	Supported only for single-AZ tasks
From the cloud	GaussDB(for MySQL)->GaussDB(DWS)	Supported	Supported only for single-AZ tasks
From the cloud	GaussDB(for MySQL)->Kafka	Supported	Supported only for single-AZ tasks
From the cloud	GaussDB(for MySQL)->CSS/ES	Supported	Supported only for single-AZ tasks
From the cloud	GaussDB(for MySQL)->Oracle	Supported	Supported only for single-AZ tasks
From the cloud	MariaDB->MariaDB	Supported	Supported only for single-AZ tasks
From the cloud	Microsoft SQL Server->Kafka	Not supported	Not supported
Self-built -> Self-built	MySQL->Kafka	Supported	Supported only for single-AZ tasks
Self-built -> Self-built	MySQL->CSS/ES	Supported	Supported only for single-AZ tasks
Self-built -> Self-built	MySQL -> GaussDB Primary/Standby	Supported	Supported only for single-AZ tasks
Self-built -> Self-built	MySQL -> GaussDB Distributed	Supported	Supported only for single-AZ tasks
Self-built -> Self-built	Oracle->Kafka	Supported	Supported only for single-AZ tasks
Self-built -> Self-built	Oracle -> GaussDB Primary/Standby	Supported	Supported only for single-AZ tasks
Self-built -> Self-built	Oracle -> GaussDB Distributed	Supported	Supported only for single-AZ tasks
Self-built -> Self-built	PostgreSQL->Kafka	Supported	Supported only for single-AZ tasks
Self-built -> Self-built	GaussDB Primary/Standby -> MySQL	Supported	Supported only for single-AZ tasks
Self-built -> Self-built	GaussDB Primary/Standby -> Oracle	Supported	Supported only for single-AZ tasks
Self-built -> Self-built	GaussDB Primary/Standby -> Kafka	Supported	Supported only for single-AZ tasks
Self-built -> Self-built	GaussDB Primary/Standby -> GaussDB Distributed	Supported	Supported only for single-AZ tasks
Self-built -> Self-built	GaussDB Primary/Standby -> GaussDB Primary/Standby	Supported	Supported only for single-AZ tasks
Self-built -> Self-built	GaussDB Distributed -> MySQL	Supported	Supported only for single-AZ tasks
Self-built -> Self-built	GaussDB Distributed -> Oracle	Supported	Supported only for single-AZ tasks
Self-built -> Self-built	GaussDB Distributed -> Kafka	Supported	Supported only for single-AZ tasks
Self-built -> Self-built	GaussDB Distributed->GaussDB Primary/Standby	Supported	Supported only for single-AZ tasks
Self-built -> Self-built	GaussDB Distributed -> GaussDB Distributed	Supported	Supported only for single-AZ tasks
Self-built -> Self-built	DB2 for LUW -> GaussDB Primary/Standby	Not supported	Not supported
Self-built -> Self-built	DB2 for LUW -> GaussDB Distributed	Not supported	Not supported
Self-built -> Self-built	Microsoft SQL Server->Kafka	Not supported	Not supported