add rfcs for datafusion

docs/source/community/communication.md

@@ -76,9 +76,8 @@ Our source code is hosted on
 [GitHub](https://github.com/apache/arrow-datafusion). For developers new to
 the project, we have curated a
 [good-first-issue](https://github.com/apache/arrow-datafusion/issues?q=is%3Aissue+is%3Aopen+label%3A%22good+first+issue%22)
-list to help you get started.
+list to help you get started. You can find datafusion's major designs in docs/source/specification.
 
 We use GitHub issues for maintaining a queue of development work and as the
 public record. We often use Google docs, Github issues and pull requests for
-quick and small design discussions. For major design change proposals, please
-make sure to send them to the dev list for more visibility.
+quick and small design discussions. For major design change proposals, we encourage you to write a rfc.

docs/source/specification/rfcs/template.md

@@ -0,0 +1,58 @@
+<!---
+  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.
+-->
+
+Feature Name:
+
+Status: draft/in-progress/completed/
+
+Start Date: YYYY-MM-DD
+
+Authors:
+
+RFC PR: #
+
+Datafusion Issue: #
+
+---
+
+### Background
+
+---
+
+### Goals
+
+---
+
+### Non-Goals
+
+---
+
+### Survey
+
+---
+
+### General design
+
+---
+
+### Detailed design
+
+---
+
+### Others