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ReplaceSavePoint
Maintain a moving savepoint within a transaction.
Short Name
SPCLSAV()
Type
Low-Level data file function.
Declaration
LONG SPCLSAV(VOID)
LONG ReplaceSavePoint(VOID)
Description
Call ReplaceSavePoint() to establish a savepoint while at the same time clearing the previous savepoint. ReplaceSavePoint() can be used to maintain a single “moving” savepoint within a transaction, which is useful for applications that may need to undo the work since the last savepoint but that never need to restore back to a point prior to the most recent savepoint. ReplaceSavePoint() provides this ability in the form of a single savepoint rather than multiple savepoints. Because ReplaceSavePoint() clears the previous savepoint, only the most recently established savepoint can be restored to. To restore to this savepoint, call TRANRST(-1).
Return
ReplaceSavePoint() returns a non-zero value to indicate success and a value of zero to indicate failure. If the return value is zero, uerr_cod contains the c-tree error code. If a client supports ReplaceSavePoint() but the server does not, the message:
Bad raw function #. fn: 231
will be placed in CTSTATUS.FCS and the c-tree error SFUN_ERR (170) will be returned. A RestoreSavePoint() cannot go back beyond a special save point set with SPCLSAV(). Further, ClearSavePoint() cannot clear a special save point. Either of these situations returns a SPCL_ERR (753).
Example
An example of the use of SPCLSAV() is within the c-treeSQL Server engine that must be able to undo the last update, and may involve a very large number of updates within a single transaction.
See also
SetSavePoint(), RestoreSavePoint()
