LOCKSIZE (ANY)? Or (PAGE)? Or
How granular should locking
If all of the programs that do inserts,
updates and deletes run in less than 15 seconds (the default timeout limit) or do commits with flawless
restart logic, congratulations. You have a well-written application. Your reward is that you can specify
LOCKSIZE (PAGE) for your tables and prevent lock escalation from happening.
What is lock escalation and why should you want
to prevent it?
Lock escalation upgrades all of your page (or row)
locks to one tablespace lock. That means no one else can access the table while you are using it. DB2
does this when you have taken so many locks that you are causing the list of all locks for everyone to become
too large. Exclusive use of a table usually causes issues... Like no parallel
What about LOCKSIZE
Don't go there. The overhead is considerable and in
over 20 years of DB2 tuning, I've never seen the need for it. Try LOCKSIZE (PAGE) before LOCKSIZE
(ROW), but only if you know for certain you are not getting escalations. If you are getting
escalations, switching from ANY to either one could seriously increase the size of your locklist and affect
all active DB2 processes.
all of the batch programs that do inserts, updates and deletes don't run in less than 15 seconds or do
commits with flawless restart logic?
LOCKSIZE (ANY) is your only option. If lock
escalations are happening, you cannot do parallel processing of the tables being escalated. This is
(part of) the cost of not having a well-written application.