I registered as reviewer on this, but after reading the whole thread for the second time, it's still not clear to me if the last two submitted patches (0001-Add-auto_explain.publish_plans.patch and 0002-Add-SHM-table-of-contents-to-the-explain-DSM.patch) are still needed reviews, since multiple refactoring ideas and objections have been raised since.
I looked into it more deeply and decided partial EXPLAINs aren't very useful yet.
I've got some thoughts around that which I'll publish when I have more time. I suggest this is a good idea, just needs some serious committer-love, so we should bounce this for now.
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Simon Riggs http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services