Progress
DataServer
for ODBC Guide
Exclusive Locks
When you update, delete, or create a record, an ODBC data source puts an exclusive lock on the record; however, the data source does not apply the exclusive lock to a record until all shared locks on it are released. Therefore, you cannot perform an update on a record until other users release it. If a record has an exclusive lock on it, no other user can access it until it is released at the end of a transaction. In a Progress transaction block, the data source always holds an exclusive lock until the end of a transaction’s scope if the data source driver supports commitment control boundaries and the ODBC AUTOCOMMIT feature is not turned on.
Exclusive locking significantly affects the performance of data sources that use page-level locking, especially if the transaction requires a large number of exclusive locks on non-contiguous records.
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