SQL That Meant Well – DataGeek.blog

March 14, 2019 Uncategorized

SQL That Meant Well: Where Functions are Applied

Not only was this delete running unreasonably slow – it was also causing lock timeouts on the MEMBER table while running because of the slowness. This post contains application specific details that you don’t need to understand the underlying concept here, which applies across many SQL statements in the real world. Continue reading »

March 8, 2019 Uncategorized

SQL That Meant Well: Applying Conditions in the Subquery vs the Outer Query

This is a new series that has been percolating in my head for a while. When I help clients with SQL, we’re often adding (or removing) indexes to help SQL performance. It has been said (though not by me) that SQL re-write is obsolete because the Db2 Optimizer will take care of that.… Read the rest

October 27, 2015 Uncategorized

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)) = ?

… Read the rest Continue reading »