**Updating the performance version I want to change the performance version of the master instance. For example, I might want to go up from MS4 to MS5 or go down from MS6 to MS5. Will the version for subordinate instances be updated as well? **
A: The performance version for subordinate instances will not change with that of the master instance. However, you can change the performance version of slave instances separately.
**I want to use the master-suborindate replication function, but my database instance is on version 5.5. What should I do? **
Master-subordinate replication supports only version 5.6 and later.You can manually upgrade the database implementation to version 5.6 or 5.7 first, and then use the replicate function.
**There is sometimes a very high latency between my master and subordinate instances (for example, more than five minutes). What causes this? **
High latency between master and subordinate instances can be caused by any of the following situations:
- If you have not set up a primary key, replication will require a full table scan of the subordinate instance, which can severely affect performance.Individual full table update operations can even cause the subordinate instance to jam.
- The subordinate instance also needs a lot of time to perform the update when a large amount of data is being updated, which can jam replication and cause delays.
- If the read-only instance configuration is too low, it will not be possible to perform updates as fast as on the master instance.
- Large amounts of read operations from the suborindate instance will affect the simultaneous implementation of updates generated on the master instance.
- It is essential to set up a primary key for the database. Not doing so might result in replication slowing down or even jamming up.
- Upgrading the performance version of read-only instances can directly increase throughput for read-only instances. This allows updates to be performed more quickly and speeds up the synchronization process, while also enabling rapid responses for read operations.
- If a particular query phrase is very time-sensitive, it will fail to meet requirements no matter how much it is shortened, so you can run the query on the master database.However, this process means that you need to specify a particular query phrase to run on a particular instance.