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Posted to derby-dev@db.apache.org by "Rick Hillegas (JIRA)" <ji...@apache.org> on 2010/07/23 20:42:49 UTC
[jira] Issue Comment Edited: (DERBY-672) Re-enable user defined
aggregates
[ https://issues.apache.org/jira/browse/DERBY-672?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12457874#action_12457874 ]
Rick Hillegas edited comment on DERBY-672 at 7/23/10 2:42 PM:
--------------------------------------------------------------
I do not see ANSI syntax for this feature. Here is the syntax used by some other databases.
----------------------------------------
Cloudscape 3.5:
CREATE AGGREGATE AggregateName FOR
{ JavaClassName | ClassAlias }
The aliased class has to be an implementation of a Cloudscape interface (COM.cloudscape.aggregates.AggregateDefinition). That, in turn, means that the class has to implement a couple methods:
accumulate() -- accumulator for non-grouped results
getResult() -- the final result of the accumulation
merge() -- accumulator for grouped results
---------------------------------------
Postgres 8.0.0:
CREATE AGGREGATE name (
BASETYPE = input_data_type,
SFUNC = sfunc,
STYPE = state_data_type
[ , FINALFUNC = ffunc ]
[ , INITCOND = initial_condition ]
)
Here
SFUNC is the name of an accumulator function
FFUNC is the name of a function which returns the accumulated result
-----------------------------------------------------------
IBM Informix:
CREATE AGGREGATE average
WITH (
INIT = initFunction,
ITER = iterationFunction,
COMBINE = combinationFunction,
FINAL = resultFunction
)
where
initFunction is a function initializing the accumulator
iterationFunction a counting function
combinationFunction an accumulator function
resultFunction a function which returns the accumulated result
-----------------------------------------------------------
Oracle:
In Oracle, you define a UDT which implements an aggregator interface. Then you bind that UDT to an aggregate name. See http://download.oracle.com/docs/cd/B28359_01/appdev.111/b28425/aggr_functions.htm
CREATE TYPE MyAggregatorRoutines(
STATIC FUNCTION ODCIAggregateInitialize( ... ) ...,
MEMBER FUNCTION ODCIAggregateIterate(...) ... ,
MEMBER FUNCTION ODCIAggregateMerge(...) ...,
MEMBER FUNCTION ODCIAggregateTerminate(...)
);
CREATE TYPE BODY MyAggregatorRoutines IS
...
END;
CREATE FUNCTION MyAggregate(x SomeDataType) RETURN SomeDataType
AGGREGATE USING MyAggregateRoutines;
was (Author: rhillegas):
I do not see ANSI syntax for this feature. Here is the syntax used by some other databases.
----------------------------------------
Cloudscape 3.5:
CREATE AGGREGATE AggregateName FOR
{ JavaClassName | ClassAlias }
The aliased class has to be an implementation of a Cloudscape interface (COM.cloudscape.aggregates.AggregateDefinition). That, in turn, means that the class has to implement a couple methods:
accumulate() -- accumulator for non-grouped results
getResult() -- the final result of the accumulation
merge() -- accumulator for grouped results
---------------------------------------
Postgres 8.0.0:
CREATE AGGREGATE name (
BASETYPE = input_data_type,
SFUNC = sfunc,
STYPE = state_data_type
[ , FINALFUNC = ffunc ]
[ , INITCOND = initial_condition ]
)
Here
SFUNC is the name of an accumulator function
FFUNC is the name of a function which returns the accumulated result
-----------------------------------------------------------
IBM Informix:
CREATE AGGREGATE average
WITH (
INIT = initFunction,
ITER = iterationFunction,
COMBINE = combinationFunction,
FINAL = resultFunction
)
where
initFunction is a function initializing the accumulator
iterationFunction a counting function
combinationFunction an accumulator function
resultFunction a function which returns the accumulated result
> Re-enable user defined aggregates
> ---------------------------------
>
> Key: DERBY-672
> URL: https://issues.apache.org/jira/browse/DERBY-672
> Project: Derby
> Issue Type: Improvement
> Components: SQL
> Reporter: Rick Hillegas
>
> Nicolas Dufour in an email thread titled "functions and list" started on November 2, 2005 requests the ability to create user defined aggregates.
> This functionality used to be in Cloudscape. It was disabled presumably because it was considered non-standard. However, most of the machinery needed for this feature is still in the code. We should re-enable user defined aggregates after we agree on acceptable syntax.
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