Re: Wait event names mismatch: oldserxid

On Fri, Feb 09, 2018 at 06:04:39PM +0530, Ashutosh Bapat wrote:
> Name for wait event "LWTRANCHE_OLDSERXID_BUFFERS" is printed as
> "oldserxid", but documentation at
> https://www.postgresql.org/docs/10/static/monitoring-stats.html does
> not have exact same event there. Instead it has
>
> OldSerXidLock Waiting to read or record conflicting serializable
> transactions.

I see two events defined here in the code of type LWLock dedicated to
oldserxid:
- OldSerXidLock which is a wait event defined as it is part of
LWLockNames.
- oldserxid, which gets defined in SimpleLruInit(), which itself calls
LWLockRegisterTranche() to define a second event of type LWLock.

So the docs look correct to me on this side. What I find weird is the
phrasing to define oldserxid. Instead of that, the current description:
Waiting to I/O on an oldserxid buffer.
I would suggest "waiting *for* I/O"

A small patch is attached.

Thanks,
--
Michael