mysql transaction vs lock

I have a question regarding MySQL locking and transaction management.
My Question is ..does mysql takes lock on the the tuple/table on which I am doing select/update in a transaction ?

With MyISAM, you can use the concurrent_insert=2 optimization, where an INSERT will not block existing or new SELECT statements (but will block anything else).

With InnoDB, the rules are:

• SELECTs never block

• An UPDATE or DELETE on a row will place

a lock on said row. But this can work even while the same row is
being SELECTed.

• A second update (on concurrent transaction) on

same row will block, until the first is committed or rolled back.

• INSERTs are more complicated: if the table has an AUTO_INCREMENT, then that is locked (though other concurrent operations are allowed if not competing for AUTO_INCREMENT)

• Some concurrent INSERTs may block one another because locking is done over the clustered index.

• DELETEs, UPDATEs on ranges are also more complex and may involve firther blocks due to locks on clustered index.

This is probably not a thorough list, but should get you the general picture.

StackExchange Database Administrators Q#22321, answer score: 6