Re: LOCK for non-tables

On Fri, 2011-01-14 at 13:58 -0500, Tom Lane wrote:
> Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> > Tom - I am willing to implement this if you think it's valuable, but
> > I'd like your input on the syntax.
> > http://archives.postgresql.org/pgsql-hackers/2011-01/msg00472.php
>
> It looks to me like the reason why there's a shift/reduce conflict is
> not so much that TABLE is optional as that we allow the syntax
>
> LOCK tablename NOWAIT
>
> If that weren't possible, then a table name would have to be followed by
> EOL or IN (which is full-reserved), while an optional object type name
> could not be followed by either, so there would be no shift/reduce
> conflict. So we broke it when we added NOWAIT, not when TABLE was made
> optional.
>
> So it looks to me like there are at least two fixes other than the ones
> you enumerated:
>
> 1. Make NOWAIT a reserved word. Not good, but perhaps better than
> reserving all the different object type names.
>
> 2. Disallow the above abbreviated syntax; allow NOWAIT only after an
> explicit IN ... MODE phrase. This would probably break a couple of
> applications, but I bet a lot fewer than changing the longer-established
> parts of the command syntax would break.
>
> I think #2 might be the best choice here.

There's a similar issue on my new syntax for skipping the validation
check on FKs. I'd appreciate it if you could propose a solution there
also. I'm not sure whether I solved it, or am adding issues for the
future.

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