Re: Wrong statistics for size of XLOG_SWITCH during pg_waldump.

On Sat, Oct 10, 2020 at 09:50:02AM +0800, movead.li@highgo.ca wrote:
>> I think that the length of the XLOG_SWITCH record is no other than 24
>> bytes. Just adding the padding? garbage bytes to that length doesn't
>> seem the right thing to me.
> 
> Here's the lookes:
> rmgr: XLOG        len (rec/tot):     24/    24, tx:          0, lsn: 0/030000D8, prev 0/03000060, desc: SWITCH, trailing-bytes: 16776936


 static void
-XLogDumpRecordLen(XLogReaderState *record, uint32 *rec_len, uint32 *fpi_len)
+XLogDumpRecordLen(XLogReaderState *record, uint32 *rec_len, uint32 *fpi_len, uint32 *junk_len)
 {
If you wish to add more information about a XLOG_SWITCH record, I
don't think that changing the signature of XLogDumpRecordLen() is
adapted because the record length of this record is defined as
Horiguchi-san mentioned upthread, and the meaning of junk_len is
confusing here.  It seems to me that any extra information should be
added to xlog_desc() where there should be an extra code path for
(info == XLOG_SWITCH).  XLogReaderState should have all the
information you are lookng for.
--
Michael