:Apsaradb for MySQL read /write splitting

Overview

This topic describes how to read /write splitting to apsaradb RDS for MySQL instances.

Detail

The MySQL instance read /write splitting involves the following knowledge points.

• Transactions and stored procedure are sent to the Master instance for execution.

• When the synchronization delay of a read-only Slave instance exceeds the threshold, the Slave node sends a request to the Master instance.

• The number of connections to the read /write splitting address depends on the minimum number of connections in the Master instance and read-only Slave instance, rather than the sum of connections in all instances.

• The whitelist of read /write splitting addresses depends on the whitelist of the Master instance.

• Special circumstances description.

• The latter two select statements request the Master instance.

  set autocommit=0;
  update xxx
  select xxx
  select xxx

• The first select statement requests the read-only Slave instance, the update statement and subsequent statements request the Master instance. Therefore, all select statements created before the first update statement send requests to read-only Slave instances. However, you must use the read-only weights specified for these Slave instances.

  set autocommit=0;
  select xxx
  update xxx
  select xxx

• Statements starting with start or begin request from the Master instance.

Application scope

• Apsaradb RDS for MySQL