Purge the row(s) from page.
Purge the row(s) from page, get rid of the row(s) and slot(s) - USE WITH CAUTION, please see entire description of this operation before attempting to use this. Starting from the specified slot, n rows will be purged. That is, rows that occupies from slot to slot+n-1 will be purged from the page.
Locking Policy
Calls the lockRecordForWrite() method of the LockingPolicy object passed to the openContainer() call before the records are purged.
NOTE : CAVEAT
This operation will physically get rid of the row from the page, so if a subsequent operation on this page uses a slot that has been purged, then the undo of this operation will fail. It is only safe to use this operation if the caller knows that it has exclusive access to the page for the duration of the transaction, i.e, effectively holding a page lock on the page
NOTE
Outstanding handles to purged rows are no longer valid, accessing them will cause an exception to be thrown.
NOTE : Data Logging for Purges
needDataLogged is used to specify whether data is required to be logged for purge operatios. Data Logging is required Only if the row can be reused or required for key search if a purge is rolled back;(rollback can occur if the system crashes in the middle of purges or some unexpected error condiditions rolled back. For example: 1)Btree expects the data to be there if a purge is rolled back; needDataLogged=true 2)Heaps does not care if data exist because only operation that can occur on a row whose purge rolled back is purging again.(needDataLogged=false) MT - latched
@param slot the starting slot number
@param numpurges number of slots to purge. If <= 0, just returns as a no-op.
@param needDataLogged if set to true data is logged for purges else only headers.
@exception StandardException Standard Derby error policy
@see LockingPolicy