feat: support show function for DataFrame

datafusion/src/dataframe.rs

@@ -223,6 +223,21 @@ pub trait DataFrame: Send + Sync {
     /// ```
     async fn collect(&self) -> Result<Vec<RecordBatch>>;
 
+    /// Print results.
+    ///
+    /// ```
+    /// # use datafusion::prelude::*;
+    /// # use datafusion::error::Result;
+    /// # #[tokio::main]
+    /// # async fn main() -> Result<()> {
+    /// let mut ctx = ExecutionContext::new();
+    /// let df = ctx.read_csv("tests/example.csv", CsvReadOptions::new())?;
+    /// df.show().await?;
+    /// # Ok(())
+    /// # }
+    /// ```
+    async fn show(&self) -> Result<()>;
+
     /// Executes this DataFrame and returns a stream over a single partition
     ///
     /// ```

datafusion/src/execution/dataframe_impl.rs

@@ -35,6 +35,7 @@ use crate::physical_plan::{
     execute_stream, execute_stream_partitioned, ExecutionPlan, SendableRecordBatchStream,
 };
 use async_trait::async_trait;
+use crate::arrow::util::pretty;
 
 /// Implementation of DataFrame API
 pub struct DataFrameImpl {
@@ -156,6 +157,12 @@ impl DataFrame for DataFrameImpl {
         Ok(collect(plan).await?)
     }
 
+    // Print results.
+    async fn show(&self) -> Result<()> {
+        let results = self.collect().await?;
+        Ok(pretty::print_batches(&results)?)
+    }
+
     /// Convert the logical plan represented by this DataFrame into a physical plan and
     /// execute it, returning a stream over a single partition
     async fn execute_stream(&self) -> Result<SendableRecordBatchStream> {