MySQL for Oracle DBA
Q) RMAN is the online backup tool for oracle. MySQL backup for MySQL, is it capable to do point in time recovery?

A) MySQL use mysqldump as online backup tool.

Q) In Oracle, an instance starts with memory structure SGA. How does it work in MySQL?

A) In MySQL, tuning of the caches similar to Oracle’s buffer cache is done on a per storage engine basis. For the MyISAM engine, the key_buffer can be used to cache index data only, and relies on the underlying operating system to cache data files unlike Oracle’s buffer cache. Because of this difference, while a dedicated Oracle database might allocate 80% of the system’s main memory to the buffer cache, often MySQL’s key buffer does not get set to much over 50% of the database system’s main memory for optimal tuning.

MySQL’s InnoDB storage engine has a more similar cache to Oracle’s buffer cache called innodb_buffer_pool_size and caches both index and data blocks. Like Oracle’s buffer pool, a dedicated MySQL system using only InnoDB tables would do well to set to up 80% of the systems main memory for use in this cache.

Q) I don't understand logging and database files layout in MySQL In Oracle if i create tablespace we see a file on the file system with name. How does this work in MySQL?

A) Each database managed by the MySQL server has its own database directory. This exists as a subdirectory of the data directory, with the same name as the database it represents. For example, a database mydb corresponds to the database directory DATADIR/mydb. This representation allows several database-level statements to be almost trivial in their implementation.

Q) In Oracle we have to put the database in archive log mode, do we have to do this with MySQL to perform point in time recovery?

A)  I found something similar to this question in https://stackoverflow.com/questions/65093/best-way-to-archive-live-mysql-database