[GitHub] [spark] HyukjinKwon commented on a change in pull request #30816: [SPARK-33818][SQL][DOC] Add descriptions about `spark.sql.parser.quotedRegexColumnNames` in the SQL documents

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

HyukjinKwon commented on a change in pull request #30816:
URL: https://github.com/apache/spark/pull/30816#discussion_r551728579



##########
File path: docs/sql-ref-syntax-qry-select-regex-column.md
##########
@@ -0,0 +1,82 @@
+---
+layout: global
+title: Regex Column Names
+displayTitle: Regex Column Names
+license: |
+  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.
+---
+
+### Description
+
+When `spark.sql.parser.quotedRegexColumnNames` is true, quoted Identifiers (using backticks) in SELECT statement are interpreted as regular expressions and SELECT statement can take regex-based column specification.
+
+### Syntax
+
+```sql
+SELECT `regex` FROM ...
+```
+
+### Parameters
+    
+* **regex**
+
+    Quoted Java regex syntax to represents all of the input attributes to a given relational operator.
+
+### Examples
+
+```sql
+CREATE TABLE person (id INT, name STRING, age INT, class INT, address STRING);
+INSERT INTO person VALUES
+    (100, 'John', 30, 1, 'Street 1'),
+    (200, 'Mary', NULL, 1, 'Street 2'),
+    (300, 'Mike', 80, 3, 'Street 3'),
+    (400, 'Dan', 50, 4, 'Street 4');
+SET spark.sql.parser.quotedRegexColumnNames=true;
+
+SELECT `(class|address)?+.+` FROM person;

Review comment:
       Yeah, I would prefer to don't have a dedicated page.




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