Primary key conflict resolution during primary primary replication

The problem that must be avoided under master and master replication-synchronization conflict

Example:

Create table stu (

Id int primary key auto_increment.

).

2 mysql have equal status, if 2 requests arrive at 2 servers at the same time

The requested A node, the id of stu is 1

The requested B node, the id of stu is 1

Synchronization-> conflict

How to solve?

Let 1 server grow from 1 to 3 to 5 to 7.

The other server, 2pencils, 4pencils, 6pens, 8s to grow.

One server:

Set global auto_increment_increment = 2

Set global auto_increment_offset = 1

Set session auto_increment_increment = 2

Set session auto_increment_offset = 1

Another server:

Set global auto_increment_increment = 2

Set global auto_increment_offset = 2

Set session auto_increment_increment=2

Set session auto_increment_offset = 2

Note: auto-increment-increment and auto-increment-offset should be written to the configuration file to prevent failure after the next restart.

Similar results are obtained after operation as follows

If you need to add a server at a later stage, this method is limited.

We can solve it in terms of business logic.

For example, there is a sequnce sequence in oracle.

Each time the sequence is accessed, increasing / decreasing data is generated.

Taking redis as an example, we can build a special global:userid.

Every time PHP is inserted into Mysql, incr- > global:userid is used to get a non-repetitive userid.