Lock Level MVCC and Readlock
When a table is opened, the settings for isolation level, lock level, and readlock affect the locking strategy used by Actian X.
The installation defaults for these settings are the DBMS configuration parameters:
• system_isolation
• system_lock_level
• system_readlock
The session can override readlock using:
SET LOCKMODE SESSION WHERE LEVEL=... READLOCK=
If READLOCK = NOLOCK, read nolock protocols are used even if the lock level is MVCC.
If READLOCK = EXCLUSIVE or SHARED and lock level is MVCC, then MVCC protocols are used.
Last modified date: 04/03/2024