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MySQL uses table-level locking for MyISAM and MEMORY tables, page-level locking for BDB tables, and row-level locking for InnoDB tables. How do I know this? I

• known 18y ago
  I am trying to understand the technical differences between Oracle and MySQL locks for e.g. F_SETLKW This argument tells fcntl() to attempt to obtain the lock requested in the struct flock structure. If the lock cannot be obtained (since someone else has it locked already), fcntl() will wait (block) until the lock has cleared, then will set it itself. This is a very useful command. I use it all the time. F_SETLK This function is almost identical to F_SETLKW. The only difference is that this one will not wait if it cannot obtain a lock. It will return immediately with -1. This function can be used to clear a lock by setting the l_type field in the struct flock to F_UNLCK. F_GETLK If you want to only check to see if there is a lock, but don't want to set one, you can use this command. It looks through all the file locks until it finds one that conflicts with the lock you specified in the struct flock. It then copies the conflicting lock's information into the struct and returns it to you. If it can't find a conflicting lock, fcntl() returns the struct as you passed it, except it sets the l_type field to F_UNLCK.