Github user ijokarumawak commented on a diff in the pull request:
https://github.com/apache/nifi/pull/2737#discussion_r194216928
--- Diff:
nifi-nar-bundles/nifi-standard-bundle/nifi-standard-processors/src/main/java/org/apache/nifi/processors/standard/RecordStats.java
---
@@ -0,0 +1,225 @@
+/*
+ * 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 org.apache.nifi.processors.standard;
+
+import com.google.common.collect.Lists;
+import org.apache.nifi.annotation.behavior.InputRequirement;
+import org.apache.nifi.annotation.behavior.WritesAttribute;
+import org.apache.nifi.annotation.behavior.WritesAttributes;
+import org.apache.nifi.annotation.documentation.CapabilityDescription;
+import org.apache.nifi.annotation.documentation.Tags;
+import org.apache.nifi.annotation.lifecycle.OnScheduled;
+import org.apache.nifi.components.PropertyDescriptor;
+import org.apache.nifi.expression.ExpressionLanguageScope;
+import org.apache.nifi.flowfile.FlowFile;
+import org.apache.nifi.processor.AbstractProcessor;
+import org.apache.nifi.processor.ProcessContext;
+import org.apache.nifi.processor.ProcessSession;
+import org.apache.nifi.processor.Relationship;
+import org.apache.nifi.processor.exception.ProcessException;
+import org.apache.nifi.processor.util.StandardValidators;
+import org.apache.nifi.record.path.FieldValue;
+import org.apache.nifi.record.path.RecordPath;
+import org.apache.nifi.record.path.RecordPathResult;
+import org.apache.nifi.record.path.util.RecordPathCache;
+import org.apache.nifi.serialization.RecordReader;
+import org.apache.nifi.serialization.RecordReaderFactory;
+import org.apache.nifi.serialization.record.Record;
+
+import java.io.InputStream;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+@Tags({ "record", "stats", "metrics" })
+@CapabilityDescription("A processor that can count the number of items in
a record set, as well as provide counts based on " +
+ "user-defined criteria on subsets of the record set.")
+@InputRequirement(InputRequirement.Requirement.INPUT_REQUIRED)
+@WritesAttributes({
+ @WritesAttribute(attribute = RecordStats.RECORD_COUNT_ATTR,
description = "A count of the records in the record set in the flowfile.")
--- End diff --
Please add `recordStats.<User Defined Property Name>.count` and
`recordStats.<User Defined Property Name>.count.<value>`
---
