pg.ddx.io pgsql-bugs@postgresql.org mailing list archive help / color / mirror / Atom feed From: Tom Lane <tgl@sss.pgh.pa.us>
To: Amit Langote <amitlangote09@gmail.com>
Cc: Tender Wang <tndrwang@gmail.com>
Cc: Michael Paquier <michael@paquier.xyz>
Cc: exclusion@gmail.com
Cc: pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #18657: Using JSON_OBJECTAGG with volatile function leads to segfault
Date: Fri, 18 Oct 2024 13:22:05 -0400
Message-ID: <907538.1729272125@sss.pgh.pa.us> (raw )
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Amit Langote <amitlangote09@gmail.com> writes:
> Another version which expands the comment of JsonValueExpr a little further.
I still don't like this approach to eval_const_expressions one bit.
It's undocumented and it pessimizes as many cases as it optimizes.
Sure, in the case where we can fold formatted_expr to a constant,
we avoid processing raw_expr at all --- but if we fail to do that,
we end by recursively simplifying formatted_expr twice (and raw_expr
once). That's not a win.
I think it should look more like
/*
* If we can fold formatted_expr to a constant, we can elide
* the JsonValueExpr altogether. Otherwise we must process
* raw_expr too. But JsonFormat is a flat node and requires
* no simplification, only copying.
*/
formatted = eval_const_expressions_mutator((Node *) jve->formatted_expr,
context);
if (formatted && IsA(formatted, Const))
return formatted;
newnode = makeNode(JsonValueExpr);
newnode->formatted_expr = formatted;
newnode->raw_expr = eval_const_expressions_mutator((Node *) jve->raw_expr,
context);
newnode->format = copyObject(jve->format);
return newnode;
(Untested, probably requires more casts than I wrote.)
Also, in primnodes.h, personally I'd write
+ Expr *raw_expr; /* user-specified expression */
"raw" is a misnomer here, and even if we're not going to rename the
field, we're not helping anyone by using that word in the comment.
regards, tom lane
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Cc: tgl@sss.pgh.pa.us, amitlangote09@gmail.com, tndrwang@gmail.com, michael@paquier.xyz, exclusion@gmail.com, pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #18657: Using JSON_OBJECTAGG with volatile function leads to segfault
In-Reply-To: <907538.1729272125@sss.pgh.pa.us>
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