On 18 December 2014 at 02:48, Simon Riggs <si...@2ndquadrant.com> wrote: > > > David, if you can update your patch with some docs to explain the > behaviour, it looks complete enough to think about committing it in > early January, to allow other patches that depend upon it to stand a > chance of getting into 9.5. (It is not yet ready, but I see it could > be). > > Sure, I've more or less added the docs from your patch. I still need to trawl through and see if there's anywhere else that needs some additions.
> The above example is probably the best description of the need, since > user defined aggregates must also understand this. > > Could we please call these "combine functions" or other? MERGE is an > SQL Standard statement type that we will add later, so it will be > confusing if we use the "merge" word in this context. > > Ok, changed. > David, your patch avoids creating any mergefuncs for existing > aggregates. We would need to supply working examples for at least a > few of the builtin aggregates, so we can test the infrastructure. We > can add examples for all cases later. > > In addition to MIN(), MAX(), BIT_AND(), BIT_OR, SUM() for floating point types, cash and interval. I've now added combine functions for count(*) and count(col). It seems that int8pl() is suitable for this. Do you think it's worth adding any new functions at this stage, or is it best to wait until there's a patch which can use these? Regards David Rowley
combine_aggregate_state_v2.patch
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