Re: Transactions involving multiple postgres foreign servers, take 2

Hi Sawada-san,


Thank you for your reply.

> Not sure but it might be possible to keep holding an xlogreader for
> reading PREPARE WAL records even after the transaction commit. But I
> wonder how much open() for wal segment file accounts for the total
> execution time of 2PC. 2PC requires 2 network round trips for each
> participant. For example, if it took 500ms in total, we would not get
> benefits much from the point of view of 2PC performance even if we
> improved it from 14ms to 1ms.

I made the patch based on your advice and re-run the test on the new machine.
(The attached patch is just for test purpose.)

* foreign_twophase_commit = disabled
2686tps

* foreign_twophase_commit = required (It is necessary to set -R ${RATE} as Ikeda-san said)
311tps

* foreign_twophase_commit = required with attached patch (It is not necessary to set -R ${RATE})
2057tps