SAVEPOINT
savepoints
defining
SAVEPOINT
7
SQL - Language Statements
SAVEPOINT
define a new savepoint within the current transaction
SAVEPOINT savepoint_name
Description
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.
Parameters
savepoint_name
The name to give to the new savepoint.
Notes
Use to
rollback to a savepoint. Use
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.
Examples
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.
Compatibility
SQL requires a savepoint to be destroyed automatically when another
savepoint with the same name is established. In
PostgreSQL, 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.
See Also