Re: Reduce pinning in btree indexes

>>>>> "Kyotaro" == Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)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)