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https://issues.apache.org/jira/browse/DRILL-8354?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17630886#comment-17630886
]
ASF GitHub Bot commented on DRILL-8354:
---------------------------------------
jnturton commented on code in PR #2703:
URL: https://github.com/apache/drill/pull/2703#discussion_r1017701372
##########
exec/java-exec/src/test/resources/jsoninput/is_empty_tests.json:
##########
@@ -0,0 +1,27 @@
+[
+ {
+ "numeric_col": 1.3,
+ "text_col": "text",
+ "list_col": [
+ "v1", "v2"
+ ],
+ "map_column": {
+ "field1": "value1",
+ "field2": "value2",
+ "nested_map": {
+ "nested_field1": "nested_value1",
+ "nested_field2" : "nested_value2"
+ }
+ }
+ },{
+ "numeric_col": 2.3,
+ "text_col": "",
+ "list_col": [],
+ "map_column": {}
+ },{
+ "numeric_col": null,
+ "text_col": null,
+ "list_col": [],
+ "map_column": {}
+ }
Review Comment:
```suggestion
}, {
"numeric_col": 1
}
```
Can we add an object that is outright missing some queried properties and
check that the is_empty unit tests pick those up as being empty?
##########
exec/java-exec/src/main/java/org/apache/drill/exec/expr/fn/impl/IsEmptyUtils.java:
##########
@@ -0,0 +1,61 @@
+/*
+ * 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.drill.exec.expr.fn.impl;
+
+import org.apache.drill.common.types.TypeProtos.MinorType;
+import org.apache.drill.exec.vector.complex.impl.SingleMapReaderImpl;
+import org.apache.drill.exec.vector.complex.reader.FieldReader;
+
+public class IsEmptyUtils {
+
+ /**
+ * This function recursively traverses a Drill map to determine whether the
map is empty or not.
+ * @param reader A {@link FieldReader} containing the field in question
+ * @return True if the field contains no data, false if it does.
+ */
+ public static boolean mapIsEmpty(FieldReader reader) {
+
+ if (reader.getType().getMinorType() == MinorType.MAP) {
+ SingleMapReaderImpl mapReader = (SingleMapReaderImpl) reader;
+
+ // If the map reader has no fields returns nothing return true
Review Comment:
```suggestion
// If the map reader has no fields return true
```
> Add IS_EMPTY Function.
> ----------------------
>
> Key: DRILL-8354
> URL: https://issues.apache.org/jira/browse/DRILL-8354
> Project: Apache Drill
> Issue Type: Improvement
> Components: Functions - Drill
> Affects Versions: 1.20.2
> Reporter: Charles Givre
> Assignee: Charles Givre
> Priority: Major
> Fix For: 2.0.0
>
>
> When analyzing data, there is currently no single function to evaluate
> whether a given field is empty. With scalar fields, this can be accomplished
> with the `IS NOT NULL` operator, but with complex fields, this is more
> challenging as complex fields are never null.
> This PR adds a UDF called IS_EMPTY() which accepts any type of field and
> returns true if the field does not contain data.
>
> In the case of scalar fields, if the field is `null` this returns true. In
> the case of complex fields, which can never be `null`, in the case of lists,
> the function returns true if the list is empty. In the case of maps, it
> returns true if all of the map's fields are unpopulated.
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