Category: Performance

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Ember’s Take on Monitoring DB2 LUW

I have some very specific perspectives on monitoring DB2. In addition to regular consulting in my day job, we also provide full-service virtual DBA services, including monitoring. The monitoring we choose to do is very much under my control, and I’m constantly working on enhancements. I thought I’d blog on what I like to monitor and alert on without going...

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Comparing dsmtop and db2top

dsmtop is a long-awaited refresh of the wildly popular db2top. Like db2top, dsmtop is a free tool, included with DB2. It is in the base DB2 install starting with 11.1, and can be installed on DB2 10.1 or 10.5. History of db2top As I personally recall, db2top first came out of IBM AlphaWorks. My understanding of IBM AlphaWorks is that...

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The Role of the DB2 DBA in Load/Performance Testing

I am consistently shocked and appalled at how few clients actually do load testing. Many pay it lip service, but few actually engage in real, meaningful performance and load testing. I understand that load testing of an application can be difficult and expensive. It is not something that every developer has as a part of their toolkit. But the most...

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DB2 Memory Area In-Depth: The Package Cache

The package cache is just one memory area that DB2 offers to tune memory usage for a DB2 database. This article is a deep dive into this memory area. What is the Package Cache The package cache is an area of memory that DB2 uses to store access plans. Access plans are detailed strategies for how DB2 will get to...

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A Physical DBA Reviewing DDL

My background comes largely from the physical DBA world, though I’ve gained logical DBA skills over the years. Any reasonably mature IT organization will have a DBA at some level or another review SQL and DDL before it is implemented in production. Why Reviewing SQL and DDL is Important Reviewing SQL and DDL is important because there are some very...

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DB2 Basics: Isolation Levels and Concurrency Phenomena

Isolation levels are such a critical concept to maximizing concurrency for transaction processing databases where ACID is so critical. What is ACID? ACID stands for Atomicity, Consistency, Isolation, Durability. This is a set of concepts that applies to any transaction processing system, whether it is a Relational Database Management System (like DB2) or not. ACID is one of the big...

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Looking at Sort Memory Performance on BLU

Performance tuning of BLU databases is an evolving topic at this time. For BLU databases, sort memory cannot be tuned by STMM, and so must be manually tuned. BLU also makes extensive use of sort memory. It is a bit of a misnomer at this point. It is more of a working memory area that is used for hashes, grouping,...

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A Faster Way of Joining When Applying a Distinct

I have been paying a bit of attention to cross-platform SQL optimization lately, and read this interesting post: https://www.periscopedata.com/blog/use-subqueries-to-count-distinct-50x-faster.html?utm_content=bufferaf11f&utm_medium=social&utm_source=linkedin.com&utm_campaign=buffer Being a bit of an experimenter, the first thing that I wondered is how DB2 would handle this scenario. Would the DB2 optimizer be smarter than others, or would the same hold true for DB2 that held true for PostgreSQL? Environment...