Mainframe Performance Topics with Martin Packer

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Search and Replace with the new DFSORT functional PTFs

MartinPacker Comments (2) Visits (25716)

Here's my first tip with the new UK90006 / UK90007 DFSORT PTFs. It's an apparently minor enhancement that I think people will like... It leads to a more elegant syntactical expression. It is more maintainable - in the face of changing record layouts. Suppose you want to search a file for a string in a particular position in each record and replace all matching instances with a different string. (... [More]

Tags: dfsort

DFSORT New Function PTFs

MartinPacker Comment (1) Visits (7858)

As many of you know I like to beta DFSORT function PTFs. About once a year a new set of functions appears, many in direct response to customer requirements. Occasionally some of the enhancements are at my suggestion. :-) Yesterday PTFs UK90006 and UK90007 became available. (Being UK based it's nice to see PTF numbers beginning with UK but I read no significance into this.) :-) You can read the... [More]

Tags: parse dfsort

My New Job

MartinPacker Visits (4240)

As of today I have a new job. I still work for IBM. I'm still UK based. I still do performance analysis with customers in the same way. But some things have changed: I now work in Software Group, rather than what's now called Global Technology Services . I now have a geographical territory that stretches from Rejkavik to Vladivostok, and from Stavanger to Cape Town. I would quite like to visit all... [More]

DB2 Data Sharing Performance for Beginners

MartinPacker Comment (1) Visits (7117)

I'm strongly considering writing a DB2 Data Sharing For Beginners presentation. In fact I have a proposal in to do just such a thing for the US z/OS Conference (in Orlando in October). Obviously that would be a presentation I'd like to take to eg UKCMG and the EMEA z/OS Conference next year. Would this be of general interest? When I say For Beginners I'm not entirely sure I mean that. :-)... [More]

Another MIDAWs APAR - Might Improve Its Performance

MartinPacker Visits (4035)

In this entry I talked about an APAR that fixed an issue with mixed farms of control units, where only some supported MIDAWs. Here's another APAR. This one could increase the performance benefit of MIDAWs. APAR OA15556 changes the way IDAWs (Indirect Data Access Words) are placed in memory, relative to the CCWs (Channel Command Words)... (M)IDAWs point at the data for the I/O and CCWs point at... [More]

More REORG Utility Flexibility

MartinPacker Comment (1) Visits (6174)

Long ago the DB2 REORG utility traded memory for speed with SORTKEYS and SORTDATA. The latter caused the object being REORGed to be unloaded and externally sorted (eg using DFSORT). (SORTKEYS was similar but for the keys to REORG the indexes.) This is fine if you have the memory to drive either large in-memory sorts or multiple parallel sorts. But sometimes you don't. APAR PK18059 for V8... [More]

Some SQL Access Path Improvements

MartinPacker Visits (3646)

Just briefly, here are some Access Path fixes I've been meaning to talk about: PK14923 QUERY COST ESTIMATE IS TOO HIGH IN SOME CASES PK16521 ONE FETCH INDEX ACCESS (I1) NOT USED WITH DUPLICATE PREDICATES PK15143 POOR QUERY PERFORMANCE WHEN SORT MERGE JOIN IS CHOSEN AND MULTIPLE JOIN COLUMNS ARE POSSIBLE OR COL=LIT EXISTS ON SMJ KEY PK20229 POOR QUERY PERFORMANCE WHEN FETCH FIRST 1 ROW AND INDEX... [More]

DDF Row Counts Bug

MartinPacker Visits (3884)

One of the themes for Distributed access to DB2 that I talk about is Network Flows Optimisation , in particular ensuring that DB2 is taking advantage of such things as blocking... When DB2 sends rows back to a DDF caller it can block them or return them singly (and indeed the degree of blocking can vary). Appropriate levels of blocking can reduce network traffic, optimising the bandwidth and... [More]

DB2 As A Web Services Provider

MartinPacker Comment (1) Visits (6418)

I present at conferences on what I call New World DB2 application performance, by which I mean such things as Stored Procedures, SAP R/3 and BW, Distributed (DDF) and JDBC. I do this because I think us mainframe performance people need to lead conversations on DB2 application performance that actually acknowledge what the installation is trying to do with DB2. Often it's not the common or garden... [More]

Lotus Sametime 7.5 Alpha 2

MartinPacker Visits (3609)

A little off-topic, perhaps, but I've just installed the second Alpha of Lotus Sametime 7.5, IBM's recently-previewed new instant messaging client. I would've liked to have installed the first Alpha but I've been working hard on behalf of one of my favourite clients until yesterday. There's that phrase again, Brian. :-) Actually, I am favourably impressed with 7.5, particularly as it's based on an... [More]

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