Update datafusion-examples README

.github/workflows/rust.yml

@@ -120,6 +120,7 @@ jobs:
           cargo run --example parquet_sql
           cargo run --example parquet_sql_multiple_files
           cargo run --example memtable
+          cargo run --example rewrite_expr
           cargo run --example simple_udf
           cargo run --example simple_udaf
 

README.md

@@ -100,7 +100,7 @@ Here are some of the projects known to use DataFusion:
 
 ## Example Usage
 
-Please see [example usage](https://arrow.apache.org/datafusion/user-guide/example-usage.html) to find how to use DataFusion.
+Please see the [example usage](https://arrow.apache.org/datafusion/user-guide/example-usage.html) in the user guide and the [datafusion-examples](https://github.com/apache/arrow-datafusion/tree/master/datafusion-examples) crate for more information on how to use DataFusion.
 
 ## Roadmap
 

datafusion-examples/README.md

@@ -0,0 +1,47 @@
+<!---
+  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.
+-->
+
+# DataFusion Examples
+
+This crate includes several examples of how to use various DataFusion APIs and help you on your way.
+
+Prerequisites:
+
+Run `git submodule update --init` to init test files.
+
+## Single Process
+
+- [`avro_sql.rs`](examples/avro_sql.rs): Build and run a query plan from a SQL statement against a local AVRO file
+- [`csv_sql.rs`](examples/csv_sql.rs): Build and run a query plan from a SQL statement against a local CSV file
+- [`custom_datasource.rs`](examples/custom_datasource.rs): Run queris against a custom datasource (TableProvider)
+- [`dataframe.rs`](examples/dataframe.rs): Run a query using a DataFrame against a local parquet file
+- [`dataframe_in_memory.rs`](examples/dataframe_in_memory.rs): Run a query using a DataFrame against data in memory
+- [`deserialize_to_struct.rs`](examples/deserialize_to_struct.rs): Convert query results into rust structs using serde
+- [`expr_api.rs`](examples/expr_api.rs): Use the `Expr` construction and simplification API
+- [`memtable.rs`](examples/memtable.rs): Create an query data in memory using SQL and `RecordBatch`es
+- [`parquet_sql.rs`](examples/parquet_sql.rs): Build and run a query plan from a SQL statement against a local Parquet file
+- [`parquet_sql_multiple_files.rs`](examples/parquet_sql_multiple_files.rs): Build and run a query plan from a SQL statement against multiple local Parquet files
+- [`query-aws-s3.rs`](examples/query-aws-s3.rs): Confiure `object_store` and run a query against files stored in AWS S3
+- [`rewrite_expr.rs`](examples/rewrite_expr.rs): Define and invoke a custom Query Optimizer pass
+- [`simple_udaf.rs`](examples/simple_udaf.rs): Define and invoke a User Defined Aggregate Function (UDAF)
+- [`simple_udf.rs`](examples/simple_udf.rs): Define and invoke a User Defined (scalar) Function (UDF)
+
+## Distributed
+
+- [`flight-client.rs`](examples/flight-client.rs) and [`flight-server.rs`](examples/flight-server.rs): Run DataFusion as a standalone process and execute SQL queries from a client using the Flight protocol.