From: Michael Paquier <michael@paquier.xyz>
To: chaitanyyachoudhary@gmail.com
To: pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #19693: JSON_VALUE/JSON_QUERY PASSING a toasted text value reads the toast pointer instead of the text
Date: Sat, 19 Sep 2026 09:12:46 +0900
Message-ID: <aq3TflHWHS-407w0@paquier.xyz> (raw)
In-Reply-To: <19693-2ecd2b52c838b3e5@postgresql.org>
References: <19693-2ecd2b52c838b3e5@postgresql.org>
On Fri, Sep 18, 2026 at 02:39:08AM +0000, PG Bug reporting form wrote:
> The datum is never detoasted, so for an out-of-line value the macros read
> the toast pointer's own bytes. The value comes from the PASSING argument
> via GetJsonPathVar() -> JsonItemFromDatum(var->value, ...) and nothing on
> that path detoasts it either. The other varlena cases in this function
> (JSONB, and the datetime types through their output paths) go through code
> that detoasts.
>
> Fix: detoast the datum in that case, for example
>
> text *txt = DatumGetTextPP(val);
> res->val.string.val = VARDATA_ANY(txt);
> res->val.string.len = VARSIZE_ANY_EXHDR(txt);
>
> The same code is present on REL_18_STABLE and master as of 2026-09-17.
At quick glance, your take seems right and that looks like an
oversight. Would you like to write a patch?
--
Michael
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To: pgsql-bugs@postgresql.org
Cc: michael@paquier.xyz, chaitanyyachoudhary@gmail.com, pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #19693: JSON_VALUE/JSON_QUERY PASSING a toasted text value reads the toast pointer instead of the text
In-Reply-To: <aq3TflHWHS-407w0@paquier.xyz>
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