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. .

 

 
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 …
Db2 for z/OS: Using the Profile Tables to Direct DDF Applications to Particular Package CollectionsI've posted several entries to this blog on the topic of high-performance DBATs (for example, one from a few years ago covered a MAXDBAT implication related to high-performance DBAT usage). You may well be aware that a "regular" DBAT (a DBAT being a DDF thread) becomes a high-performance DBAT when a…
Db2 for z/OS PBG Table Spaces: The Ins and Outs of Partition AdditionIn an entry posted to this blog about three years ago, I advocated for putting some thought into the PBG versus PBR decision (partition-by-growth versus partition-by-range) for larger tables (for smaller tables, PBG is often the sensible choice, especially when the associated table space is likely t…
Db2 for z/OS Buffer Pools: Index Root Pages and the Data Management ThresholdSometimes, a change in the way Db2 for z/OS manages its resources is introduced, and the change "flies under the radar" (i.e, it escapes the notice of most Db2 users) because it is relatively small in terms of scope and impact and is not widely highlighted in the product documentation, and it delive…
Db2 for z/OS Buffer Pools - Time to Give AUTOSIZE(YES) a Try?Db2 9 for z/OS became generally available back in 2007. In the years since, most of the features introduced with Db2 9 have been broadly put to use. An interesting exception is the auto-sizing of buffer pools, implemented via the AUTOSIZE(YES) option of the -ALTER BUFFERPOOL command. Based on my exp…