Re: WAL usage calculation patch

On Mon, Mar 30, 2020 at 6:14 PM Julien Rouhaud <rjuju123(at)gmail(dot)com> wrote:
>
@@ -448,6 +449,7 @@ XLogInsert(RmgrId rmid, uint8 info)
bool doPageWrites;
XLogRecPtr fpw_lsn;
XLogRecData *rdt;
+ int num_fpw = 0;

/*
* Get values needed to decide whether to do full-page writes. Since
@@ -457,9 +459,9 @@ XLogInsert(RmgrId rmid, uint8 info)
GetFullPageWriteInfo(&RedoRecPtr, &doPageWrites);

rdt = XLogRecordAssemble(rmid, info, RedoRecPtr, doPageWrites,
- &fpw_lsn);
+ &fpw_lsn, &num_fpw);

- EndPos = XLogInsertRecord(rdt, fpw_lsn, curinsert_flags);
+ EndPos = XLogInsertRecord(rdt, fpw_lsn, curinsert_flags, num_fpw);
} while (EndPos == InvalidXLogRecPtr);

I think there are some issues in the num_fpw calculation. For some
cases, we have to return from XLogInsert without inserting a record.
Basically, we've to recompute/reassemble the same record. In those
cases, num_fpw should be reset. Thoughts?

--
Thanks & Regards,
Kuntal Ghosh
EnterpriseDB: http://www.enterprisedb.com