[postgis-devel] Re: [Bizgres-general] Bizgres MPP and PostGIS

[Markus Schaber]

Hi, Luke,

Luke Lonergan wrote:

> I understand that we've added an API extension to the "CREATE AGGREGATE"
> statement.  Normally it takes two arguments, now it takes three, the third
> being there to act as an accumulator (Brian, Alon, perhaps you can
> elaborate).

Ah, that clears it up, thanks.

So the 9 aggregates defined by PostGIS would need to be extended by an
accumulator. Should be a straight-forward task, AFAICS.

> With our upcoming (early November) release, I understand that we support the
> UDFs (including those written in "C"), custom types and parallel aggregation
> needed by PostGIS.  The one exception we can think of is that we still don't
> support TRIGGERs.  Does PostGIS still need them?

AFAICS, PostGIS needs triggers for "long time transaction support"
(which I never looked at closely). There's an cache_bbox trigger
function one can explicitly add to control bbox caching handling, too.

There are also CHECK constraints to enforce consistency for OpenGIS
compliant tables, but well-behaving applications (or those deliberately
not relying on OpenGIS compliance by creating mixed-type columns) can do
without them.

So, I'd say, PostGIS core functionality is available without triggers,
but some extended functionality needs it.

HTH,
Markus
-- 
Markus Schaber | Logical Tracking&Tracing International AG
Dipl. Inf.     | Software Development GIS

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