Stephan Szabo <[EMAIL PROTECTED]> writes: > On Tue, 26 Aug 2003, Ang Chin Han wrote: >> Veering aside a bit, since we usually pinpoint performance problems by >> looking at EXPLAIN ANALYZE's differences between the planner's >> estimation and actual execution's stats, what's involved in parsing the >> EXPLAIN ANALYZE results, and highlighting the places where they are way >> different? Bold, underline, or put some asterisks in front of those steps.
> The hardest part is determining where it matters I think. You can use the > row counts as the base for that, but going from 1 row to 50 is not > necessarily going to be an issue, but it might be if a nested loop is > chosen. We've been chatting about this idea among the Red Hat group. The RHDB Visual Explain tool (get it at http://sources.redhat.com/rhdb/) already computes the percent of total runtime represented by each plan node. It seems like we could highlight nodes based on a large difference between estimated and actual percentage, or just highlight the nodes that are more than X percent of the runtime. regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 7: don't forget to increase your free space map settings
