On Thu, Feb 22, 2018 at 8:28 AM, Peter Geoghegan <p...@bowt.ie> wrote: > On Wed, Feb 21, 2018 at 3:02 PM, R, Siva <sivas...@amazon.com> wrote: >> Did you mean pin on the metapage buffer during ginInsertCleanup and not lock >> during addition of tuples to the accumulator? The exclusive lock on metapage >> buffer is released after reading/locking head of pending list and before we >> process pages/add tuples to the accumulator in ginInsertCleanup [1]. > > AFAICT, nobody ever holds just a pin on the metapage as some kind of > interlock (since nobody else ever acquires a "super exclusive lock" on > the metapage -- if anybody else ever did that, then simply holding a > pin might make sense as a way of blocking the "super exclusive" lock > acquisition). Maybe you're thinking of the root page of posting trees? > > I think that Sawada-san simply means that holding an ExclusiveLock on > the metapage makes writers block each other, and concurrent VACUUMs. > At least, for as long as they're in ginInsertCleanup().
Yes, but I realized my previous mail was wrong, sorry. Insertion to pending list doesn't acquire ExclusiveLock on metapage. So we can insert tuples to pending list while cleaning up. Regards, -- Masahiko Sawada NIPPON TELEGRAPH AND TELEPHONE CORPORATION NTT Open Source Software Center
