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 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

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