scan , can be aged out of the buffer pool sooner than with a strict  LRU  algorithm. For more information, see Section 15.5.1, “Buffer Pool” . See Also buffer pool, full table scan, LRU, page.  An internal phase of  InnoDB  processing, when making changes at the  physical  level to internal data structures during  DML  operations. A mini-transaction (mtr) has no notion of  rollback ; multiple mini-transactions can occur within a single  transaction . Mini-transactions write information to the  redo log  that is used during  crash recovery . A mini-transaction can also happen outside the context of a regular transaction, for example during purge  processing by background threads. See Also commit, crash recovery, DML, physical, purge, redo log, rollback, transaction.  An  INSERT  statement where  auto-increment  values are specified for some but not all of the new rows. For example, a multi-value  INSERT  could specify a value for the auto-increment column in some cases and  NULL in other cases.  InnoDB  generates auto-increment values for the rows where the column value was specified as NULL . Another example is an  INSERT ... ON DUPLICATE KEY UPDATE  statement, where auto-increment values might be generated but not used, for any duplicate rows that are processed as  UPDATE  rather than INSERT  statements. Can cause consistency issues between  source  and  replica  servers in a  replication  configuration. Can require adjusting the value of the  innodb_autoinc_lock_mode  configuration option. See Also auto-increment, innodb_autoinc_lock_mode, replica, replication, source.  An older JDBC driver for MySQL that evolved into  Connector/J  when it was integrated with the MySQL product. See Also Connector/J.  An Open Source framework developed by Novell, that works with  Connector/NET  and  C#  applications on Linux platforms. See Also Connector/NET, C#. See mini-transaction.  A type of processor that can take advantage of multithreaded programs, such as the MySQL server. multiversion concurrency control See MVCC.  Informal abbreviation for “mutex variable” . (Mutex itself is short for “mutual exclusion” .) The low-level object that  InnoDB  uses to represent and enforce exclusive-access  locks  to internal in-memory data structures. Once the lock is acquired, any other process, thread, and so on is prevented from acquiring the same lock. Contrast with  rw-locks , which  InnoDB  uses to represent and enforce shared-access  locks  to internal in-memory data structures. Mutexes and rw-locks are known collectively as  latches . See Also latch, lock, Performance Schema, Pthreads, rw-lock.  Acronym for “multiversion concurrency control” . This technique lets  InnoDB transactions  with certain  isolation levels  perform  consistent read  operations; that is, to query rows that are being updated by other transactions, and see the values from before those updates occurred. This is a powerful technique to increase  concurrency , by allowing queries to proceed without waiting due to  locks  held by the other transactions. mini-transaction mixed-mode insert MM.MySQL Mono mtr multi-core mutex MVCC 6168