Add roadmap to readme (#1616)

* Add roadmap to readme

* Link to datafusion-contrib

* Update multi column comparisons

Author: matthewmturner

README.md

@@ -141,6 +141,60 @@ datafusion = "6.0.0"
 
 DataFusion also includes a simple command-line interactive SQL utility. See the [CLI reference](https://arrow.apache.org/datafusion/cli/index.html) for more information.
 
+# Roadmap
+
+A quarterly roadmap will be published to give the DataFusion community visibility into the priorities of the projects contributors. This roadmap is not binding.
+
+## 2022 Q1
+
+### DataFusion Core
+
+- Publish official Arrow2 branch
+- Implementation of memory manager (i.e. to enable spilling to disk as needed)
+
+### Benchmarking
+
+- Inclusion in Db-Benchmark with all quries covered
+- All TPCH queries covered
+
+### Performance Improvements
+
+- Predicate evaluation
+- Improve multi-column comparisons (that can't be vectorized at the moment)
+- Null constant support
+
+### New Features
+
+- Read JSON as table
+- Simplify DDL with Datafusion-Cli
+- Add Decimal128 data type and the attendant features such as Arrow Kernel and UDF support
+- Add new experimental e-graph based optimizer
+
+### Ballista
+
+- Begin work on design documents and plan / priorities for development
+
+### Extensions ([datafusion-contrib](https://github.com/datafusion-contrib]))
+
+- Stable S3 support
+- Begin design discussions and prototyping of a stream provider
+
+## Beyond 2022 Q1
+
+There is no clear timeline for the below, but community members have expressed interest in working on these topics.
+
+### DataFusion Core
+
+- Custom SQL support
+- Split DataFusion into multiple crates
+- Push based query execution and code generation
+
+### Ballista
+
+- Evolve architecture so that it can be deployed in a multi-tenant cloud native environment
+- Ensure Ballista is scalable, elastic, and stable for production usage
+- Develop distributed ML capabilities
+
 # Status
 
 ## General