[GitHub] [beam] lostluck commented on a change in pull request #11936: [BEAM-9679] Add CombinePerKey to Core Transforms Go Katas

[GitBox <gi...@apache.org>]

lostluck commented on a change in pull request #11936:
URL: https://github.com/apache/beam/pull/11936#discussion_r437014738



##########
File path: learning/katas/go/Core Transforms/Combine/Combine PerKey/task.md
##########
@@ -0,0 +1,47 @@
+<!--
+  ~  Licensed to the Apache Software Foundation (ASF) under one
+  ~  or more contributor license agreements.  See the NOTICE file
+  ~  distributed with this work for additional information
+  ~  regarding copyright ownership.  The ASF licenses this file
+  ~  to you under the Apache License, Version 2.0 (the
+  ~  "License"); you may not use this file except in compliance
+  ~  with the License.  You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~  Unless required by applicable law or agreed to in writing, software
+  ~  distributed under the License is distributed on an "AS IS" BASIS,
+  ~  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~  See the License for the specific language governing permissions and
+  ~  limitations under the License.
+  -->
+
+# Combine - Combine PerKey

Review comment:
       Space between Per and Key please. "PerKey" isn't anything at all, but we're describing that we're combining values per key. here and throughout.

##########
File path: learning/katas/go/Core Transforms/Combine/Combine PerKey/task.md
##########
@@ -0,0 +1,47 @@
+<!--
+  ~  Licensed to the Apache Software Foundation (ASF) under one
+  ~  or more contributor license agreements.  See the NOTICE file
+  ~  distributed with this work for additional information
+  ~  regarding copyright ownership.  The ASF licenses this file
+  ~  to you under the Apache License, Version 2.0 (the
+  ~  "License"); you may not use this file except in compliance
+  ~  with the License.  You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~  Unless required by applicable law or agreed to in writing, software
+  ~  distributed under the License is distributed on an "AS IS" BASIS,
+  ~  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~  See the License for the specific language governing permissions and
+  ~  limitations under the License.
+  -->
+
+# Combine - Combine PerKey
+
+After creating a keyed PCollection (for example, by using a GroupByKey transform), a common pattern 
+is to combine the collection of values associated with each key into a single, merged value. This 
+pattern of a GroupByKey followed by merging the collection of values is equivalent to Combine 
+PerKey transform. The combine function you supply to Combine PerKey must be an associative 
+reduction function or a subclass of CombineFn.

Review comment:
       There are no "subclasses" in Go.

##########
File path: learning/katas/go/Core Transforms/Combine/Combine PerKey/cmd/main.go
##########
@@ -0,0 +1,49 @@
+// Licensed to the Apache Software Foundation (ASF) under one or more
+// contributor license agreements.  See the NOTICE file distributed with
+// this work for additional information regarding copyright ownership.
+// The ASF licenses this file to You under the Apache License, Version 2.0
+// (the "License"); you may not use this file except in compliance with
+// the License.  You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"combine_perkey/pkg/task"
+	"context"
+	"github.com/apache/beam/sdks/go/pkg/beam"
+	"github.com/apache/beam/sdks/go/pkg/beam/log"
+	"github.com/apache/beam/sdks/go/pkg/beam/x/beamx"
+	"github.com/apache/beam/sdks/go/pkg/beam/x/debug"
+)
+
+func main() {
+	ctx := context.Background()
+
+	p, s := beam.NewPipelineWithRoot()
+
+	input := beam.ParDo(s, func(_ []byte, emit func(string, int)){

Review comment:
       KV's can't be created directly in the Go SDK at this time.  They need to be emitted from a DoFn like this.




----------------------------------------------------------------
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.

For queries about this service, please contact Infrastructure at:
users@infra.apache.org