On Thu, Apr 23, 2020 at 2:35 PM Amit Kapila <amit.kapil...@gmail.com> wrote: > > On Thu, Apr 23, 2020 at 12:16 PM Peter Eisentraut > <peter.eisentr...@2ndquadrant.com> wrote: > > > The internal symbol for the WAL record is > > XLOG_FPI and xlogdesc.c prints it as "FPI". > > > > That is just one way/reason we log the page. There are others as > well. I thought here we are computing the number of full-page writes > happened in the system due to various reasons like (a) a page is > operated upon first time after the checkpoint, (b) log the XLOG_FPI > record, (c) Guc for WAL consistency checker is on, etc. If we see in > XLogRecordAssemble where we decide to log this information, there is a > comment " .... log a full-page write for the current block." and there > was an existing variable with 'fpw_lsn' which indicates to an extent > that what we are computing in this patch is full-page writes. But > there is a reference to full-page image as well. I think as > full_page_writes is an exposed variable that is well understood so > exposing information with similar name via this patch doesn't sound > illogical to me. Whatever we use here we need to be consistent all > throughout, even pg_stat_statements need to name exposed variable as > wal_fpi instead of wal_fpw. > > To me, full-page writes sound more appealing with other WAL usage > variables like records and bytes. I might be more used to this term as > 'fpw' that is why it occurred better to me. OTOH, if most of us think > that a full-page image is better suited here, I am fine with changing > it at all places. >
Julien, Peter, others do you have any opinion here? I think it is better if we decide on one of FPW or FPI and make the changes at all places for this patch. -- With Regards, Amit Kapila. EnterpriseDB: http://www.enterprisedb.com
