Why do we expand tuples in execMain.c?

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.

cheers

andrew

--

Andrew Dunstan https://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

On August 9, 2018 1:33:17 AM GMT+05:30, Andrew Dunstan <andrew.dunstan@2ndquadrant.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
--
Sent from my Android device with K-9 Mail. Please excuse my brevity.

On 08/08/2018 09:15 PM, Andres Freund wrote:

On August 9, 2018 1:33:17 AM GMT+05:30, Andrew Dunstan <andrew.dunstan@2ndquadrant.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?

Yeah, I think you're right, and this is vestigial code that I neglected
to remove when cleaning up from development.

I'll fix it.

cheers

andrew

--
Andrew Dunstan https://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services