Re: [BUGS] Server crash while trying to read expression using pg_get_expr()

From: Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>
To: Florian Pflug <fgp(at)phlo(dot)org>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Robert Haas <robertmhaas(at)gmail(dot)com>, Kris Jurka <books(at)ejurka(dot)com>, Rushabh Lathia <rushabh(dot)lathia(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, Rushabh Lathia <rushabh(dot)lathia(at)enterprisedb(dot)com>
Subject: Re: [BUGS] Server crash while trying to read expression using pg_get_expr()
Date: 2010-06-30 10:11:43
Message-ID: 4C2B185F.9020607@enterprisedb.com
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On 15/06/10 15:19, Florian Pflug wrote:
> On Jun 15, 2010, at 9:31 , Heikki Linnakangas wrote:
>> You could avoid changing the meaning of fn_expr by putting the check in the parse analysis phase, into transformFuncCall(). That would feel safer at least for back-branches.
>
> For 9.0, wouldn't a cleaner way to accomplish this be a seperate type for expressions, say pg_expr, instead of storing them as text? With an input function that unconditionally raises and error and no cast to pg_expr, creating new instances of that type would be impossible for normal users. The output function and casts to text would call pg_get_expr() with zero as the second argument.
>
> The internal representation wouldn't change, it's just the type's OID in the catalog that'd be different.

Yeah, that would be quite elegant. I think it's too late for 9.0, but
something to consider in the future.

--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com

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