I have read about MySQL. In my opinion, I see two log types as very similar. MySQL saves how and when data is changed in log. Information is used for recovery of MySQL. I am confusing the function of two log types.

up vote 13 down vote accepted

REDO log is Oracle terminology, transaction log is InnoDB terminology. Now that all are Oracle engineers, people use both to refer to the same thing in MySQL.

The transaction log is, by default- it can be changed- the two files located in $DATADIR called ib_logfile0 and ib_logfile1. It serves the same functions as the REDO log in other databases- storing writes in a safe way and recovering in the case of a crash, although there are some details in implementation that differ in functionality from other RDMS. It is the main component for InnoDB to be a transactional engine.

Do not confuse the transaction log with the binary logs in MySQL. The binlog, by default, is on the $DATADIR and is *hostname*-bin.index and several *hostname*-bin.00001, etc. It is particular confusing for people coming from other databases, because it is used for other things that other databases use the REDO log for: replication and point in time recovery. The main difference is that the transaction log is InnoDB-only, the binary log is (mostly) transaction-independent, as it is for all storage engines, transactional or not. MyISAM will write (if enabled) to the binary log. InnoDB will write to the transaction log and the binary log.

More info on the manual: REDO log, binary log.

In SQL Server , the TLog files stores both undo and redo information. But in MYSQL and Oracle, the TLog/Redo Log stores only redo information.

Binary Loging in MySQL is a way to have point in time recovery. Enabling binary logging is equivalent to having full recovery model in SQL Server.

  • 1
    You should probably make it clear that Oracle does still store undo, albeit separately. – Philᵀᴹ Nov 5 '16 at 11:51

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