A hub for sharing relational database knowledge and experimentation
Database performance is heavily influenced by data volume and cardinality (or how unique that data may be).
It’s interesting to watch the look on someone’s face when this concept clicks. There is a look of understanding from a developer when she can extrapolate why SQL ran in seconds on a small, local, dockerized, database but the same SQL runs in minutes in a much larger QA environment.… Read the rest
Continue reading »I blogged a little while ago on how to create a basic sandbox VM for DB2. Since I’m a big fan of separating filesystems properly, I needed to learn how to add another disk and another filesystem to my sandbox VMs.… Read the rest
Continue reading »I’m a control freak. I think that control freaks tend to make good DBAs as long as they don’t take it too far. My position for years has been that I would rather control my runstats, reorgs, and backups directly than trust DB2’s automatic facilities.… Read the rest
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I’ve played with the clpplus at least once before, but have generally thought of it as a tool created to satisfy those coming from Oracle and looking for Oracle-like features. One of the features I actually liked about Oracle in the class and certification tests that I took for it was the ability to specify values for an SQL statement stored in a file on execution.… Read the rest
Continue reading »GENERATED ALWAYS can be a blessing or a curse. I’m not talking about identity columns here, but about creating a column that is actually a duplicate of some part of the data to boost performance. Sure, in 10.5 we can do indexes on expressions, but for some clients I have trouble just getting them to go to a supported level, much less the latest and greatest.… Read the rest
Continue reading »If you’re not familiar with MONREPORT, see my DB2 Basics entry on MONREPORT first.
Most of the references I’ve seen to customizing the MONREPORT module basically say “get the code out of the database, modify it, and deploy it”. (see IBM DB2 Knowledge Center Entry on Customizing the MONREPORT module reports)
I have found this rather frustrating when I’ve run across it, and when I find a lack of documentation frustrating, I tend to blog to fill the hole as much as possible.… Read the rest
Continue reading »DB2 10.1 introduced a new feature commonly called RCAC (Row and Column Access Control) or FGAC(Fine-Grained Access Control). This is a bit less labor intensive to support than LBAC (Label Based Access Control), and solves some of the problems with LBAC.… Read the rest
Continue reading »I’m always keeping an eye on Twitter to catch interesting bits of news, and that includes watching cross platform information. I find it fascinating to compare DB2 to other RDMBSes, and saw a great article from Use the Index, Luke (fabulous name!)… Read the rest
Continue reading »I have been playing a fair amount lately with clustering indexes and have been rehashing my views on reorging tables on an index. This is still a work in progress, but thought I’d share some details and see if others out there have any thoughts to share with me and others on it.… Read the rest
Continue reading »I have not made extensive use of the HADR Tools that IBM offers in the past. Most of my HADR setups to date have either been same-data-center using NEARSYNC or have used ASYNC to copy data between data centers. I haven’t had much cause to tweak my network settings or change my SYNCMODE settings based on hardware/networking.… Read the rest
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Sometimes you just have to think out of the box. Sometimes there isn’t an answer on google. Sometimes you have to bend the laws of physics to get the answer. Sometimes you get lucky.
I had a problem, I desperately needed to relocate where my instance was physically installed and move it from one filesystem to another.… Read the rest
Continue reading »We interrupt your regular programming for a quick announcement.
If you have been reading DB2commerce.com for a while you know I am an occasional guest writer on this technical blog. I’ve worked this year on expanding my comfort zone with regular articles here, a developerWorks article to be posted next week, and I have entered as a competitor on the DB2 Night Show’s “DB2s Got Talent”.… Read the rest
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