From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
Cc: Simon Riggs <simon(at)2ndquadrant(dot)com>, Andrew Dunstan <andrew(dot)dunstan(at)2ndquadrant(dot)com>, Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, Dean Rasheed <dean(dot)a(dot)rasheed(at)gmail(dot)com>
Subject: Re: WITH clause in CREATE STATISTICS
Date: 2017-05-11 19:50:19
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Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> writes:
> Tom Lane wrote:
>> Have you thought further about the upthread suggestion to just borrow
>> SELECT's syntax lock stock and barrel?

> Bison seems to like the productions below. Is this what you had in
> mind? These mostly mimic joined_table and table_ref, stripping out the
> rules that we don't need.

I'd suggest just using the from_list production and then complaining
at runtime if what you get is too complicated. Otherwise, you have
to maintain a duplicate set of productions, and you're going to be
unable to throw anything more informative than "syntax error" when
somebody tries to exceed the implementation limits.

> Note that I had to put back the FOR keyword in there; without the FOR,
> that is "CREATE STATS any_name opt_name_list expr_list FROM" there was
> one shift/reduce conflict, which I tried to solve by splitting
> opt_name_list using two rules (one with "'(' name_list ')'" and one
> without), but that gave rise to two reduce/reduce conflicts, and I didn't
> see any way to deal with them.

That's fine. I was going to suggest using ON after the stats type list
just because it seemed to read better. FOR is about as good.

> (Note that I ended up realizing that stats_type_list is unnecessary
> since we can use name_list.)


regards, tom lane

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