>>>>> "Kyotaro" == Kyotaro HORIGUCHI <horiguchi.kyot...@lab.ntt.co.jp> writes:
Kyotaro> ammarkpos/amrestrpos are called in merge joins. By the steps Kyotaro> shown below, I had 1M times of markpos and no restorepos for Kyotaro> 1M result rows, and had 500k times of markpos and the same Kyotaro> number of times of restorepos for 2M rows result by a bit Kyotaro> different configuration. I suppose we can say that they are Kyotaro> the worst case considering maskpos/restrpos. The call counts Kyotaro> can be taken using the attached patch. You might want to try running the same test, but after patching ExecSupportsMarkRestore to return false for index scans. This will cause the planner to insert a Materialize node to handle the mark/restore. This way, you can get an idea of how much gain (if any) the direct support of mark/restore in the scan is actually providing. -- Andrew (irc:RhodiumToad) -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
