Re: Use XLogFromFileName() in pg_resetwal to parse position from WAL file

At Tue, 4 Oct 2022 11:06:15 +0530, Bharath Rupireddy <bharath(dot)rupireddyforpostgres(at)gmail(dot)com> wrote in
> It looks like there's an opportunity to replace explicit WAL file
> parsing code with XLogFromFileName() in pg_resetwal.c. This was not
> done then (in PG 10) because the XLogFromFileName() wasn't accepting
> file size as an input parameter (see [1]) and pg_resetwal needed to
> use WAL file size from the controlfile. Thanks to the commit
> fc49e24fa69a15efacd5b8958115ed9c43c48f9a which added the
> wal_segsz_bytes parameter to XLogFromFileName().

Nice finding. I found a few '%08X%08X's but they don't seem to fit
similar fix.

> I'm attaching a small patch herewith. This removes using extra
> variables in pg_resetwal.c and a bit of duplicate code too (5 LOC).
>
> Thoughts?

> - segs_per_xlogid = (UINT64CONST(0x0000000100000000) / ControlFile.xlog_seg_size);
> newXlogSegNo = ControlFile.checkPointCopy.redo / ControlFile.xlog_seg_size;

Couldn't we use XLByteToSeg() here?

Other than that, it looks good to me.

> [1] https://github.com/postgres/postgres/blob/REL_10_STABLE/src/include/access/xlog_internal.h

regards.

--
Kyotaro Horiguchi
NTT Open Source Software Center