Method for optimizing index, master database node and subscriber database node

A master database node, comprising:

• a processor;
• a memory storing computer program which are reading by the processor to cause the processor to perform the following steps;
• checking if role information of an index matches role information of the master database node, when the index is added into the master database node;
• updating database information by using the index when the role information of the index matches the role information of the master database node.

A subscriber database node, comprising:

• a processor;
• a memory storing computer program which are reading by the processor to cause the processor to perform the following steps:
• updating role information of the subscriber database node when the subscriber database node is added into a cluster containing a master database node;
• sending the role information of the subscriber database node to the master database node.