[SPARK-31326][SQL][DOCS] Create Function docs structure for SQL Reference

huaxingao · maropu · commit 308a8fd3c677 · 2020-04-03T14:36:22.000+09:00
### What changes were proposed in this pull request? Create Function docs structure for SQL Reference... ### Why are the changes needed? so the Function docs can be added later, also want to get a consensus about what to document for Functions in SQL Reference. ### Does this PR introduce any user-facing change? Yes <img width="1050" alt="Screen Shot 2020-04-02 at 12 09 20 AM" src="https://user-images.githubusercontent.com/13592258/78220451-68b6e100-7476-11ea-9a21-733b41652785.png"> <img width="1051" alt="Screen Shot 2020-04-02 at 12 09 44 AM" src="https://user-images.githubusercontent.com/13592258/78220460-6ce2fe80-7476-11ea-887c-defefd55c19d.png"> <img width="1051" alt="Screen Shot 2020-04-02 at 12 10 05 AM" src="https://user-images.githubusercontent.com/13592258/78220463-6f455880-7476-11ea-81fc-fd4137db7c3f.png"> ### How was this patch tested? Manually build and check Closes #28099 from huaxingao/function. Authored-by: Huaxin Gao <huaxing@us.ibm.com> Signed-off-by: Takeshi Yamamuro <yamamuro@apache.org> (cherry picked from commit 4e45c07) Signed-off-by: Takeshi Yamamuro <yamamuro@apache.org>
diff --git a/docs/_data/menu-sql.yaml b/docs/_data/menu-sql.yaml
@@ -225,5 +225,26 @@
                   url: sql-ref-syntax-aux-resource-mgmt-list-file.html
                 - text: LIST JAR
                   url: sql-ref-syntax-aux-resource-mgmt-list-jar.html
+    - text: Functions
+      url: sql-ref-functions.html
+      subitems:
+      - text: Build-in Functions
+        url: sql-ref-functions-builtin.html
+        subitems:
+        - text: Build-in Aggregate Functions
+          url: sql-ref-functions-builtin-aggregate.html
+        - text: Build-in Array Functions
+          url: sql-ref-functions-builtin-array.html
+        - text: Build-in Date Time Functions
+          url: sql-ref-functions-builtin-date-time.html
+      - text: UDFs (User-Defined Functions)
+        url: sql-ref-functions-udf.html
+        subitems:
+        - text: Scalar UDFs (User-Defined Functions)
+          url: sql-ref-functions-udf-scalar.html
+        - text: UDAFs (User-Defined Aggregate Functions)
+          url: sql-ref-functions-udf-aggregate.html
+        - text: Integration with Hive UDFs/UDAFs/UDTFs
+          url: sql-ref-functions-udf-hive.html
     - text: Datetime Pattern
       url: sql-ref-datetime-pattern.html
diff --git a/docs/sql-ref-functions-builtin-aggregate.md b/docs/sql-ref-functions-builtin-aggregate.md
@@ -1,22 +1,22 @@
 ---
 layout: global
-title: Builtin Aggregate Functions
-displayTitle: Builtin Aggregate Functions
+title: Built-in Aggregate Functions
+displayTitle: Built-in Aggregate Functions
 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.
 ---
 
-**This page is under construction**
+Aggregate functions
diff --git a/docs/sql-ref-functions-builtin-array.md b/docs/sql-ref-functions-builtin-array.md
@@ -0,0 +1,22 @@
+---
+layout: global
+title: Built-in Array Functions
+displayTitle: Built-in Array Functions
+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.
+---
+
+Array Functions
diff --git a/docs/sql-ref-functions-builtin-date-time.md b/docs/sql-ref-functions-builtin-date-time.md
@@ -0,0 +1,22 @@
+---
+layout: global
+title: Built-in Date and Time Functions
+displayTitle: Built-in Date and Time Functions
+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.
+---
+
+Date-Time Functions
diff --git a/docs/sql-ref-functions-builtin.md b/docs/sql-ref-functions-builtin.md
@@ -1,25 +1,26 @@
 ---
 layout: global
-title: Reference
-displayTitle: Reference
+title: Built-in Functions
+displayTitle: Built-in Functions
 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.
 ---
 
-Spark SQL is Apache Spark's module for working with structured data.
-This guide is a reference for Structured Query Language (SQL) for Apache 
-Spark. This document describes the SQL constructs supported by Spark in detail
-along with usage examples when applicable.
+Spark SQL defines built-in functions to use, a complete list of which can be found [here](api/sql/). Among them, Spark SQL has several special categories of built-in functions: [Aggregate Functions](sql-ref-functions-builtin-aggregate.html) to operate on a group of rows, [Array Functions](sql-ref-functions-builtin-array.html) to operate on Array columns, and [Date and Time Functions](sql-ref-functions-builtin-date-time.html) to operate on Date and Time.
+
+* [Aggregate Functions](sql-ref-functions-builtin-aggregate.html)
+* [Array Functions](sql-ref-functions-builtin-array.html)
+* [Date and Time Functions](sql-ref-functions-builtin-date-time.html)
diff --git a/docs/sql-ref-functions-udf-hive.md b/docs/sql-ref-functions-udf-hive.md
@@ -0,0 +1,22 @@
+---
+layout: global
+title: Integration with Hive UDFs/UDAFs/UDTFs
+displayTitle: Integration with Hive UDFs/UDAFs/UDTFs
+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.
+---
+
+Integration with Hive UDFs/UDAFs/UDTFs
diff --git a/docs/sql-ref-functions-udf.md b/docs/sql-ref-functions-udf.md
@@ -1,25 +1,26 @@
 ---
 layout: global
-title: Reference
-displayTitle: Reference
+title: UDFs (User-Defined Functions)
+displayTitle: UDFs (User-Defined Functions)
 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.
 ---
 
-Spark SQL is Apache Spark's module for working with structured data.
-This guide is a reference for Structured Query Language (SQL) for Apache 
-Spark. This document describes the SQL constructs supported by Spark in detail
-along with usage examples when applicable.
+User-Defined Functions (UDFs) are a feature of Spark SQL that allows users to define their own functions when the system's built-in functions are not enough to perform the desired task. To use UDFs in Spark SQL, users must first define the function, then register the function with Spark, and finally call the registered function. The User-Defined Functions can act on a single row or act on multiple rows at once. Spark SQL also supports integration of existing Hive implementations of UDFs, UDAFs and UDTFs.
+
+* [Scalar User-Defined Functions (UDFs)](sql-ref-functions-udf-scalar.html)
+* [User-Defined Aggregate Functions (UDAFs)](sql-ref-functions-udf-aggregate.html)
+* [Integration with Hive UDFs/UDAFs/UDTFs](sql-ref-functions-udf-hive.html)
diff --git a/docs/sql-ref-functions.md b/docs/sql-ref-functions.md
@@ -1,25 +1,22 @@
 ---
 layout: global
-title: Reference
-displayTitle: Reference
+title: Functions
+displayTitle: Functions
 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.
 ---
 
-Spark SQL is Apache Spark's module for working with structured data.
-This guide is a reference for Structured Query Language (SQL) for Apache 
-Spark. This document describes the SQL constructs supported by Spark in detail
-along with usage examples when applicable.
+Spark SQL defines commonly used functions as built-in functions. It also provides User-Defined Functions (UDFs) to allow users to define their own functions when the system’s built-in functions are not enough to perform the desired task.
