Articles & Content

Robert Catterall

Robert Catterall is a well-known DB2 z/OS expert. He is a regular speaker at IDUG events and a Past President of IDUG

Note: The content of this blog is the opinion and thoughts of the blogger and does not necessarily represent the opinions of IDUG and should not be construed as reflecting official positions of the IBM Corporation. .

 

 
Db2 for z/OS: IIPHONORPRIORITY and zIIP offloadThere is something I have encountered a couple of times (most recently, just a month ago) that can have a negative performance impact on a Db2 for z/OS system, and it's something of which quite a few Db2 people are, I think, unaware. I'm referring here to the setting of a z/OS parameter called IIPHO…
Db2 12 for z/OS Statistics Profiles: Just What the Optimizer OrderedHere is an interesting story for you: not long ago, an analytics-type query was executed on a Db2 for z/OS system that had recently been migrated to Db2 12. The query was cancelled after it had run for 23 hours. A DBA noticed that there was a row for a table targeted by the query in SYSIBM.SYSTABLES…
A Case Study: Implementing a Db2 for z/OS Implicit Trusted ConnectionI've been interested in the role and trusted context features of Db2 for z/OS for a long time (I posted a two-part blog entry on the topic back in 2011). Theory is nice, but what about practice? Recently, I had an opportunity to assist a DBA in implementing implicit trusted connection functionality …
Db2 for z/OS: Isolating REST Client Activity in Db2 Monitor Accounting ReportsIn an entry posted to this blog some years ago, I described the form of a Db2 monitor-generated accounting report that I most like to use to get an overall view of application activity in a Db2 for z/OS environment: an accounting long report with data ordered by connection type (here, I am using ter…
A Case Study: Measuring the Impact of Db2 for z/OS Buffer Pool ChangesNot long ago, a Db2 for z/OS administrator contacted me with a request. His team had made some changes to the buffer pool configuration in their production Db2 environment (the overall size of the buffer pool configuration was increased to reduce read I/O activity, and greater use was made of large …
Db2 for z/OS Partitioned Table Spaces: How the Number of Partitions can Impact PerformanceThis past summer, I delivered a couple of presentations at a meeting of a regional Db2 users group in the USA. During the lunch break, I shared a table with a member of the Db2 for z/OS support team at a large financial institution. He told me an interesting story. At his site, the Db2 for z/OS team…
Db2 for z/OS Global Variables: What is a "Session"?Has this ever happened to you? You're looking at the Db2 for z/OS SQL Reference (or in the Db2 for z/OS Knowledge Center on the Web), and you see something like this (and the quote below is from the description of the CREATE VARIABLE statement in the SQL Reference, with highlighting added by me): G…
Db2 for z/OS Buffer Pools: Clearing the Air Regarding PREFETCH DISABLED - NO READ ENGINEHas this ever happened to you? You're looking at the output of a Db2 for z/OS -DISPLAY BUFFERPOOL(ACTIVE) DETAIL command, or maybe at a statistics report produced by your Db2 monitor, or maybe your Db2 monitor's online display of a subsystem's buffer pool activity, and you see for one of your buffer…
The Two Paths to the Db2 for z/OS Distributed Data FacilityIt's been almost two years since the general availability date of Db2 12 for z/OS and, by way of that new version, the availability of Db2's native REST interface (retrofitted to Db2 11 for z/OS via APARs PI66828 and PI70477). While the REST interface to Db2 is relatively new, the foundation on whic…
How Big is Big? (2018 Update - Db2 for z/OS Buffer Pools and DDF Activity)Almost 5 years ago, I posted to this blog an entry on the question, "How big is big?" in a Db2 for z/OS context. Two areas that I covered in that blog entry are buffer pool configuration size and DDF transaction volume. Quite a lot has changed since October 2013, and it's time for a Db2 "How big is …