About MySQL's connection pool shortage behavior

Document ID : KB000107782
Last Modified Date : 30/08/2018
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In MySQL of API-GW in environment setting multi-master replication
When the DB on the master side becomes insufficient in the connection pool, on the slave side it seems that processing will switch.
In that case, does the information such as insufficient connection pool remain in the log somewhere?
We assume that you accessed ssgDB here.
CA API Gateway
It appears that failover may happen whenever the application is unable to connect to a database, not only when the database completely fails. 

Whether a query is performed on the primary or secondary database is not logged by the Gateway, so the information is not available in ssg.log. If you would like to see a log when an entry is made to db2, it would make sense to configure MySQL to log that information on that node.