Re: Why do we expand tuples in execMain.c?

On August 9, 2018 1:33:17 AM GMT+05:30, Andrew Dunstan <andrew(dot)dunstan(at)2ndquadrant(dot)com> wrote:
>
>
>On 08/08/2018 12:20 AM, Andres Freund wrote:
>> Hi,
>>
>> I noticed
>> if (HeapTupleHeaderGetNatts(tuple.t_data) <
>> RelationGetDescr(erm->relation)->natts)
>> {
>> copyTuple = heap_expand_tuple(&tuple,
>> RelationGetDescr(erm->relation));
>> }
>> else
>> {
>> /* successful, copy tuple */
>> copyTuple = heap_copytuple(&tuple);
>> }
>>
>> in EvalPlanQualFetchRowMarks, and I'm somewhat confused why it's
>there?
>> If it's required here, why isn't it required in dozens of other
>places?
>>
>>
>
>
>
>Not dozens, I think, since you can't have short records for catalog
>tables, which account for most of the calls to heap_copytuple().
>
>I will look at the remainder of cases (less than 10) and reply in a day
>
>or two.

But why is it needed at all, and the deforming code at the site where we access the columns isn't sufficient?

Andres
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