During a commit operation, all changes made during a transaction are made permanent and a rollback operation is not possible after that. Depending on the transaction isolation used, this may be the first time such changes are visible to other threads.
COMMIT, create a method that
matches this definition:
int (*commit)(THD *thd, bool all);
The method name is then listed in the
(twelfth) entry of [custom-engine.html#custom-engine-handlerton
THD parameter is used to identify the
transaction that needs to be committed, while the
all parameter indicates if this is a full transaction
commit or just the end of a statement that is part of the
Details of implementing a
will vary by storage engine. Examples can be found in
If the server is in auto-commit mode, the storage engine should
automatically commit all read-only statements such as
In a storage engine, "auto-committing" works by counting locks.
Increment the count for every call to
external_lock(), decrement when
external_lock() is called with an argument of
F_UNLCK. When the count drops to zero,
trigger a commit.