On Wed, Oct 14, 2020 at 6:51 PM vignesh C <vignes...@gmail.com> wrote: > > On Fri, Oct 9, 2020 at 11:01 AM Amit Kapila <amit.kapil...@gmail.com> wrote: > > > > I am not able to properly parse the data but If understand the wal > > data for non-parallel (1116 | 0 | 3587203) and parallel (1119 > > | 6 | 3624405) case doesn't seem to be the same. Is that > > right? If so, why? Please ensure that no checkpoint happens for both > > cases. > > > > I have disabled checkpoint, the results with the checkpoint disabled > are given below: > | wal_records | wal_fpi | wal_bytes > Sequential Copy | 1116 | 0 | 3587669 > Parallel Copy(1 worker) | 1116 | 0 | 3587669 > Parallel Copy(4 worker) | 1121 | 0 | 3587668 > I noticed that for 1 worker wal_records & wal_bytes are same as > sequential copy, but with different worker count I had noticed that > there is difference in wal_records & wal_bytes, I think the difference > should be ok because with more than 1 worker the order of records > processed will be different based on which worker picks which records > to process from input file. In the case of sequential copy/1 worker > the order in which the records will be processed is always in the same > order hence wal_bytes are the same. >
Are all records of the same size in your test? If so, then why the order should matter? Also, even the number of wal_records has increased but wal_bytes are not increased, rather it is one-byte less. Can we identify what is going on here? I don't intend to say that it is a problem but we should know the reason clearly. -- With Regards, Amit Kapila.
