Just a short blog post to let everybody know that I will be in Orlando next week for the IDUG DB2 Tech Conference. I'll be delivering an education seminar (DB2 Developer's Guide Comes Alive!) on Monday and giving two presentations on Thursday...On Tuesday and Wednesday I'll be roaming around the conference, attending sessions, and looking to say hello to old friends and colleagues.Hope to see you there!IDUG NA 2...
Friday, 26 April 2013
Thursday, 25 April 2013
In the first three installments of this series on DB2 locking we have looked ata broad overview of locking (part 1), table and table space locks (part 2) and the difference between locks and latches (part 3). Today we will move ahead and discuss page and row locking.Page LockingThe types of page locks that DB2 can take are outlined in Table 1. S-locks allow data to be read concurrently but not modified. With an X-lock, data on a page can be modified...
Monday, 22 April 2013
So far in this series on DB2 locking we have offered up a broad overview of what locking is and then delved into the world of table and table space locks. In this short entry, before we tackles page and row locks, we are going to look at the difference between a lock and a latch.A true lock is handled by DB2 using the IRLM. The IRLM, or internal resource lock manager, is both a separate subsystem and an integral component of DB2. As its name implies, it manages locks for DB2.However, whenever doing so is practical, DB2 can lock resources...
Thursday, 18 April 2013
Today's post is the second in our DB2 locking series and it covers the topic of table space and table locks.Table Space LocksA table space lock is acquired when a DB2 table or index is accessed. Note that I said accessed, not updated. The table space is locked even when simple read-only access is occurring.Refer to to Table 1 below for a listing of the types of table space locks that can be acquired during the execution of an SQL statement. Every...
Monday, 15 April 2013
DB2 automatically guarantees the integrity of data by enforcing several locking strategies. These strategies permit multiple users from multiple environments to access and modify data concurrently. Basically, DB2 combines the following strategies to implement an overall locking strategy: • Table and table space locking • IRLM page and row locking • Internal page and row latching • Claims and drains to achieve partition independence • Checking commit log sequence numbers (CLSN) and PUNC bits to achieve lock avoidance ...
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