Yes, the mention of Cartesian Joins usually makes a DBA's heart skip a beat. The cartesian joins caused by missing join conditions are definitely a pain to deal with - these are the types of joins that can "blow up" temp space and cause all…
When working on a SQL Tuning issue I often kick off a SQL Tuning Advisor job on the SQL while I gather info about statistics and other things I like to check when tuning. After I get an idea of where performance might be suffering…
I recently got this error while trying to run a SQL Tuning Task against a SQL statement that was available in AWR but not currently in the library cache. I got around it by locating the SQL in OEM and using SQL Worksheet to execute…
I recently had an issue where a query being submitted to the database had a large change in performance. I could attribute the change to a recent change in object statistics, but the query wasn't behaving because of a combination of a view, subquery, UNION,…
Iggy Fernandez covers the topic of who is better suited to tune SQL - Developers or DBAs. Also listed are 5 Dangerous Beliefs which may influence the answer to that question. https://iggyfernandez.wordpress.com/2009/07/12/who-should-tune-sql-the-dba-or-the-developer/ -Dave Dangerous Belief #1: DBAs bear chief responsibility for the performance of SQL…