From: Tom Lane <tgl@sss.pgh.pa.us>
To: Alvaro Herrera <alvherre@2ndquadrant.com>
cc: Robert Haas <robertmhaas@gmail.com>,
        PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Subject: Re: Our naming of wait events is a disaster.
In-reply-to: <9871.1589321468@sss.pgh.pa.us>
References: <20200512202726.GA31125@alvherre.pgsql>
 <9871.1589321468@sss.pgh.pa.us>
Comments: In-reply-to Tom Lane <tgl@sss.pgh.pa.us>
	message dated "Tue, 12 May 2020 18:11:08 -0400"
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Date: Tue, 12 May 2020 19:41:19 -0400
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For the specific category of the heavyweight lock types, I'm
now thinking that we can't change the event names very much, because
those are also exposed in pg_locks' locktype column.  We can be
darn certain, for example, that changing the spelling of "relation"
in that column would break a lot of user queries.  Conceivably we
could decouple the wait event names from the locktype column, but
on the whole that doesn't seem like a great plan.

However, having said that, I remain on the warpath about "speculative
token".  That's an utterly horrid choice for both locktype and wait
event.  I also notice, with no amusement, that "speculative token"
is not documented in the pg_locks documentation.  So I think we should
change it ... but to what, exactly?  Looking at the other existing names:

const char *const LockTagTypeNames[] = {
	"relation",
	"extend",
	"page",
	"tuple",
	"transactionid",
	"virtualxid",
	"speculative token",
	"object",
	"userlock",
	"advisory"
};

I'm inclined to propose "spectoken".  I'd be okay with "spec_token" as
well, but there are not underscores in the longer-established names.

(Needless to say, this array is going to gain a comment noting that
there are two places to document any changes.  Also, if we split up
the wait_event table as discussed earlier, it might make sense for
pg_locks' documentation to cross-reference the sub-table for heavyweight
lock events, since that has some explanation of what the codes mean.)

			regards, tom lane