ASA Database Administration Guide
  Database Options
    Alphabetical list of options

SUBSUME_ROW_LOCKS option [database]

Function 

Controls when the engine acquires individual row locks for a table.

Allowed values 

ON, OFF

Default 

ON

Description 

If the SUBSUME_ROW_LOCKS option is ON (the default) then whenever a table t is locked exclusively with LOCK TABLE t IN EXCLUSIVE MODE, the engine will no longer acquire individual row locks for t.

This can result in a significant performance improvement if extensive updates are made to t in a single transaction, especially if t is large relative to cache size. It also allows for atomic update operations that are larger than the lock table can currently handle (> ~2-4m rows).

When this option isON, keyset cursors over a table locked in this fashion will return row changed warnings for every row in the cursor, if any row in the database has been modified. Note that the engine could turn an updateable cursor with an ORDER BY into a keyset cursor as a result.