Hi! Thanks for fixing gist amcheck! The idea of using these two patches together seems so obvious now, but never actually visited my mind before.
> 4 марта 2019 г., в 18:04, Heikki Linnakangas <hlinn...@iki.fi> написал(а): > Thanks! As I noted at > https://www.postgresql.org/message-id/2ff57b1f-01b4-eacf-36a2-485a12017f6e%40iki.fi, > the test patch left the index corrupt. I fixed it so that it leaves behind > incompletely split pages, without the corruption, see attached. It's similar > to yours, but let me recap what it does: > > * Hacks gistbuild(), create 100 empty pages immediately after the root pages. > They are leaked, so they won't be reused until the a VACUUM sees them and > puts them to the FSM > > * Hacks gistinserttuples(), to leave the split incompleted with 50% > probability > > * In vacuum, print a line to the log whenever it needs to "jump left" > > I used this patch, with the attached test script that's similar to yours, but > it also tries to verify that the index returns correct results. It prints a > result set like this: > > sum > --------- > -364450 > 364450 > (2 rows) > > If the two numbers add up to 0, the index seems valid. And you should see > "RESCAN" lines in the log, to show that jumping left happened. Because the > behavior is random and racy, you may need to run the script many times to see > both "RESCAN TRIGGERED BY NSN" and "RESCAN TRIGGERED BY FollowRight" cases. > Especially the "FollowRight" case happens less frequently than the NSN case, > you might need to run the script > 10 times to see it. Great! I've repeated your tests on my machine, I observe similar frequencies of causes of rescan left jumps. > I also tried your amcheck tool with this. It did not report any errors. > > Attached is also latest version of the patch itself. It is the same as your > latest patch v19, except for some tiny comment kibitzing. I'll mark this as > Ready for Committer in the commitfest app, and will try to commit it in the > next couple of days. That's cool! I'll work on 2nd step of these patchset to make blockset data structure prettier and less hacky. Best regards, Andrey Borodin.
