Re: Combining Aggregates

On Mon, Dec 21, 2015 at 4:53 PM, David Rowley
<david(dot)rowley(at)2ndquadrant(dot)com> wrote:
> On 22 December 2015 at 01:30, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>> Can we use Tom's expanded-object stuff instead of introducing
>> aggserialfn and aggdeserialfn? In other words, if you have a
>> aggtranstype = INTERNAL, then what we do is:
>>
>> 1. Create a new data type that represents the transition state.
>> 2. Use expanded-object notation for that data type when we're just
>> within a single process, and flatten it when we need to send it
>> between processes.
>>
>
> I'd not seen this before, but on looking at it I'm not sure if using it will
> be practical to use for this. I may have missed something, but it seems that
> after each call of the transition function, I'd need to ensure that the
> INTERNAL state was in the varlana format.

No, the idea I had in mind was to allow it to continue to exist in the
expanded format until you really need it in the varlena format, and
then serialize it at that point. You'd actually need to do the
opposite: if you get an input that is not in expanded format, expand
it.

--
Robert Haas
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