[GitHub] [arrow-datafusion] andygrove commented on a change in pull request #923: [DataFusion] - Support show function for DataFrame

[GitBox <gi...@apache.org>]

andygrove commented on a change in pull request #923:
URL: https://github.com/apache/arrow-datafusion/pull/923#discussion_r693514881



##########
File path: 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<()>;

Review comment:
       It would be nice if we could have similar behavior to Spark, where the default for `show` is to just show the first 20 rows.
   
   ```scala
   def show(numRows: Int): Unit = show(numRows, truncate = true)
   
   def show(): Unit = show(20)
   ```




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