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Archiving Transaction Logs to a Vendor Solution

I have worked with three different vendors for backup solutions for various clients in the last few months, and several others over the course of my career. When either making archive log decisions or evaluating vendors, it is important to know the DB2 details behind what is going on Why Archive Transaction Logs at All? First and foremost, archive logging...

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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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Who/What I’m Thankful for in the DB2 Community

It is a busy time of year for DBAs. Many of us will put in a large number of hours between Friday and Monday keeping ecommerce databases running and our company’s profits rolling. But it’s also a time of year in the USA where we take a moment to be thankful for the things around us and make sure that...

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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...

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Administrative SQL Cookbook: BLU Buffer Pool Hit Ratios

Purpose These statements calculates the buffer pool hit ratio for both BLU and non-BLU activity. This post includes three SQLs – for calculating at the database, bufferpool, and tablespace level. The separate BLU calculations are not yet included in sysibadm.bp_hitratio as of the writing of this article. Source While I’ve modified this statement, it comes from these two sources, both...

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Insight 2015 Brain Dump

I call my post-conference blog posts brain dumps because that is largely what they are – information formatted in a way my brain understands but not necessarily as thoroughly organized and researched as you might be used to seeing from me. Conference Generalities Overall Themes I sure wish that DB2 was more highlighted overall, but I’m sure that’s largely a...

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DB2 Administrative SQL Cookbook: Column Selectivity by Table (BLU)

Purpose This statement reports how selective at the column level queries are that run against a specific table. This does not look at overall selectivity or row selectivity. It will only work in DB2 10.5. BLU performs best when not all columns are referenced by queries. Source While I’ve modified this statement, it started with statements from these two sources,...

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Improving Performance of DBCLEAN Deletes

While this post is specific to WebSphere Commerce, it covers concepts that may apply to tuning other delete statements as well. Using Functions in the Best Place The CLEANCONF table stores the delete statements that are used by DBCLEAN. Most of them use syntax like this for the date component: (days(CURRENT TIMESTAMP) – days(prevlastsession)) >= ? Every time I see...

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DB2 Administrative SQL Cookbook: BLU Compression Ratios

Purpose This statement calculates the compression ratio for BLU tables. The compression ration can be used to help identify tables where compression is not optimal and you may need to look into why. Compression is critical to optimal performance on BLU. Understanding Compression Ratios. Compression ratios across platforms and outside of databases are generally represented as: Compression Ratio = Compressed...

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Locking Event Monitors and Compression

UPDATE, 10/21/2015: Please see the comment from IBM at the end stating that despite the information they gave Jim via PMR, this compression does not cause a lack of license compliance even if you are not licensed for compression. Abby Rosmarin said, “Hard work, determination and talent are key for any successful venture. But sometimes you need that fourth ingredient:...