SAVEPOINT — define a new savepoint within the current transaction
SAVEPOINT savepoint_name
SAVEPOINT
establishes a new savepoint within
the current transaction.
A savepoint is a special mark inside a transaction that allows all commands that are executed after it was established to be rolled back, restoring the transaction state to what it was at the time of the savepoint.
savepoint_name
The name to give to the new savepoint.
Use ROLLBACK TO SAVEPOINT to rollback to a savepoint. Use RELEASE SAVEPOINT to destroy a savepoint, keeping the effects of commands executed after it was established.
Savepoints can only be established when inside a transaction block. There can be multiple savepoints defined within a transaction.
To establish a savepoint and later undo the effects of all commands executed after it was established:
BEGIN; INSERT INTO table1 VALUES (1); SAVEPOINT my_savepoint; INSERT INTO table1 VALUES (2); ROLLBACK TO SAVEPOINT my_savepoint; INSERT INTO table1 VALUES (3); COMMIT;
The above transaction will insert the values 1 and 3, but not 2.
To establish and later destroy a savepoint:
BEGIN; INSERT INTO table1 VALUES (3); SAVEPOINT my_savepoint; INSERT INTO table1 VALUES (4); RELEASE SAVEPOINT my_savepoint; COMMIT;
The above transaction will insert both 3 and 4.
SQL requires a savepoint to be destroyed automatically when another
savepoint with the same name is established. In
LightDB, the old savepoint is kept, though only the more
recent one will be used when rolling back or releasing. (Releasing the
newer savepoint with RELEASE SAVEPOINT
will cause the older one
to again become accessible to ROLLBACK TO SAVEPOINT
and
RELEASE SAVEPOINT
.) Otherwise, SAVEPOINT
is
fully SQL conforming.