Saturday, November 9, 2013

db2top 'explain plan' - useful but unreliable

db2top is a handy tool to monitor the current database activity. One of my favourite features is the ability to 'explain' the statement present in the Dynamic query monitor screen. There is a big catcha though: it is merely showing the 'explain plan' at the time you choose to see the plan, it may or may *not* be the actual plan being used during the actual execution of the query.

Yup, it is as good as you manually running 'explain plan for <query>' without running the query.

Beware!



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