Horton

Re: wal stats questions

Fujii Masao <masao.fujii@oss.nttdata.com>

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From: Fujii Masao <masao.fujii@oss.nttdata.com>
To: Masahiro Ikeda <ikedamsh@oss.nttdata.com>, torikoshia <torikoshia@oss.nttdata.com>
Cc: pgsql-hackers@postgresql.org, andres@anarazel.de, Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Date: 2021-04-22T13:42:14Z
Lists: pgsql-hackers 

On 2021/04/21 18:31, Masahiro Ikeda wrote:
>> BTW, is it better to change PgStat_Counter from int64 to uint64 because> there aren't any counters with negative number?

On second thought, it's ok even if the counters like wal_records get overflowed.
Because they are always used to calculate the diff between the previous and
current counters. Even when the current counters are overflowed and
the previous ones are not, WalUsageAccumDiff() seems to return the right
diff of them. If this understanding is right, I'd withdraw my comment and
it's ok to use "long" type for those counters. Thought?

Regards,

-- 
Fujii Masao
Advanced Computing Technology Center
Research and Development Headquarters
NTT DATA CORPORATION

Commits

  1. Fix issues in pg_stat_wal.

  2. Change data type of counters in BufferUsage and WalUsage from long to int64.