Re: Composite Datums containing toasted fields are a bad idea(?)

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Andres Freund <andres(at)2ndquadrant(dot)com>
Cc: Noah Misch <noah(at)leadboat(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Composite Datums containing toasted fields are a bad idea(?)
Date: 2014-04-25 15:22:09
Message-ID: 7565.1398439329@sss.pgh.pa.us
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Andres Freund <andres(at)2ndquadrant(dot)com> writes:
> On 2014-04-24 19:40:30 -0400, Tom Lane wrote:
>> * Because HeapTupleGetDatum might allocate a new tuple, the wrong thing
>> might happen if the caller changes CurrentMemoryContext between
>> heap_form_tuple and HeapTupleGetDatum.

> It's fscking ugly to allocate memory in a PG_RETURN_... But I don't
> really have a better backward compatible idea :(

It's hardly without precedent; see PG_RETURN_INT64 or PG_RETURN_FLOAT8 on
a 32-bit machine, for starters. There's never been an assumption that
these macros couldn't do that.

regards, tom lane

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