Idle Transactions Kill Databases

Hung transactions in MySQL— and how to deal with them

If you have a long-running transaction, especially with ISOLATION LEVEL set to REPEATABLE READ, your database is susceptible to seeing considerable performance degradation and a possible crash. Why? Because of MVCC.

A database can only support true SERIALIZIABILITY, when there is single thread is connecting to the database so that all the commits are already in order. For instance, VoltDB does it –

By using serialized processing…