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ASF GitHub Bot commented on FLINK-2991: --------------------------------------- Github user StephanEwen commented on a diff in the pull request: https://github.com/apache/flink/pull/1605#discussion_r52599200 --- Diff: flink-runtime/src/main/java/org/apache/flink/runtime/state/AbstractStateBackend.java --- @@ -148,6 +150,18 @@ public void dispose() { abstract protected <N, T> ReducingState<T> createReducingState(TypeSerializer<N> namespaceSerializer, ReducingStateDescriptor<T> stateDesc) throws Exception; /** + * Creates and returns a new {@link FoldingState}. + * + * @param namespaceSerializer TypeSerializer for the state namespace. + * @param stateDesc The {@code StateDescriptor} that contains the name of the state. + * + * @param <N> The type of the namespace. + * @param <T> Type of the values folded into the state + * @param <ACC> Type of the value in the state * + */ + abstract protected <N, T, ACC> FoldingState<T, ACC> createFoldingState(TypeSerializer<N> namespaceSerializer, FoldingStateDescriptor<T, ACC> stateDesc) throws Exception; --- End diff -- protected abstract > Extend Window Operators to Allow Efficient Fold Operation > --------------------------------------------------------- > > Key: FLINK-2991 > URL: https://issues.apache.org/jira/browse/FLINK-2991 > Project: Flink > Issue Type: Improvement > Components: Streaming > Reporter: Aljoscha Krettek > Assignee: Aljoscha Krettek > > Right now, a window fold is implemented as a WindowFunction that gets all the > elements as input. No pre-aggregation is performed. The window operator > should be extended to also allow the fold to also be pre-aggregated. > This requires changing the signature of the {{WindowBuffer}} so that it can > emit a type other than the input type. -- This message was sent by Atlassian JIRA (v6.3.4#6332)