Re: Re: pg_stat_statements normalisation without invasive changes to the parser (was: Next steps on pg_stat_statements normalisation)

From: Daniel Farina <daniel(at)heroku(dot)com>
To: Peter Geoghegan <peter(at)2ndquadrant(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Robert Haas <robertmhaas(at)gmail(dot)com>, PG Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Re: pg_stat_statements normalisation without invasive changes to the parser (was: Next steps on pg_stat_statements normalisation)
Date: 2012-02-29 09:05:01
Message-ID: CAAZKuFZFousg18xmmLWR1E+3Z3xc2K+BUxyVei+cdix9v4zz2g@mail.gmail.com
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On Mon, Feb 27, 2012 at 4:26 AM, Peter Geoghegan <peter(at)2ndquadrant(dot)com> wrote:
> This does not appear to have any user-visible effect on caret position
> for all variations in coercion syntax, while giving me everything that
> I need. I had assumed that we were relying on things being this way,
> but apparently this is not the case. The system is correctly blaming
> the coercion token when it finds the coercion is at fault, and the
> const token when it finds the Const node at fault, just as it did
> before. So this looks like a case of removing what amounts to dead
> code.

To shed some light on that hypothesis, attached is a patch whereby I
use 'semantic analysis by compiler error' to show the extent of the
reach of the changes by renaming (codebase-wide) the Const node's
location symbol. The scope whereby the error token will change
position is small and amenable to analysis. I don't see a problem,
nor wide-reaching consequences. As Peter says: probably dead code.
Note that the cancellation of the error position happens very soon,
after an invocation of stringTypeDatum (on two sides of a branch).
Pre and post-patch is puts the carat at the beginning of the constant
string, even in event there is a failure to parse it properly to the
destined type.

--
fdr

Attachment Content-Type Size
Straw-man-to-show-the-effects-of-the-change-to-const.patch application/octet-stream 6.5 KB

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