[
https://issues.apache.org/jira/browse/PHOENIX-2144?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14642006#comment-14642006
]
ASF GitHub Bot commented on PHOENIX-2144:
-----------------------------------------
Github user petercdc commented on a diff in the pull request:
https://github.com/apache/phoenix/pull/101#discussion_r35494423
--- Diff:
phoenix-core/src/main/java/org/apache/phoenix/expression/BaseJSONExpression.java
---
@@ -0,0 +1,40 @@
+/*
+ * 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.phoenix.expression;
+
+import java.util.List;
+
+import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
+import org.apache.phoenix.expression.visitor.ExpressionVisitor;
+import org.apache.phoenix.schema.tuple.Tuple;
+import org.apache.phoenix.schema.types.PDataType;
+
+public abstract class BaseJSONExpression extends BaseCompoundExpression {
+ public BaseJSONExpression(List<Expression> children) {
+ super(children);
+ }
+ public BaseJSONExpression() {
+ }
+ public abstract boolean evaluate(Tuple tuple, ImmutableBytesWritable
ptr);
+ public abstract <T> T accept(ExpressionVisitor<T> visitor);
+ public abstract PDataType getDataType();
+ public PDataType getRealDataType(){
+ return null;
--- End diff --
Because the method -- getDataType() is used to check before evaluate the
operation , but JSON data type is hybrid data format. So if we haven't watched
the value of specific key in JSON , we cannot know the type of JSON value.
For example :
the following operation :
```
'{"a":3 , "b":"string"}' -> 'a'
```
this type will be as integer
but another operation :
```
'{"a":"string","b":2.3}' -> 'a'
```
this type will be as varchar
So we use method -- getRealDataType() to ensure the type after we evaluate
the operation
> Implement JSON operators
> -------------------------
>
> Key: PHOENIX-2144
> URL: https://issues.apache.org/jira/browse/PHOENIX-2144
> Project: Phoenix
> Issue Type: Sub-task
> Reporter: Thomas D'Silva
> Fix For: 5.0.0, 4.4.1
>
>
> See http://www.postgresql.org/docs/9.4/static/functions-json.html
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
