feat: support temporary views in DataFrameTableProvider (#18158)

## Which issue does this PR close?

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- Closes #18026

## Rationale for this change

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This makes it possible to support temporary views in datafusion-python
without code duplication.

Ref: apache/datafusion-python#1267

## What changes are included in this PR?

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PR.
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- Add new public function `DataFrame::into_temporary_view`
- Update `DataFrameTableProvider` with a new member that determines the
`table_type`
- Add a test

## Are these changes tested?

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Yes, see added test `register_temporary_table`

## Are there any user-facing changes?

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Yes, there is a new public function `DataFrame::into_temporary_view`

---------

Co-authored-by: Andrew Lamb <andrew@nerdnetworks.org>

Author: r1b

datafusion/core/src/dataframe/mod.rs

@@ -1654,7 +1654,19 @@ impl DataFrame {
     /// Note: This discards the [`SessionState`] associated with this
     /// [`DataFrame`] in favour of the one passed to [`TableProvider::scan`]
     pub fn into_view(self) -> Arc<dyn TableProvider> {
-        Arc::new(DataFrameTableProvider { plan: self.plan })
+        Arc::new(DataFrameTableProvider {
+            plan: self.plan,
+            table_type: TableType::Temporary,
+        })
+    }
+
+    /// See [`Self::into_view`]. The returned [`TableProvider`] will
+    /// create a transient table.
+    pub fn into_temporary_view(self) -> Arc<dyn TableProvider> {
+        Arc::new(DataFrameTableProvider {
+            plan: self.plan,
+            table_type: TableType::Temporary,
+        })
     }
 
     /// Return a DataFrame with the explanation of its plan so far.
@@ -2524,6 +2536,7 @@ macro_rules! dataframe {
 #[derive(Debug)]
 struct DataFrameTableProvider {
     plan: LogicalPlan,
+    table_type: TableType,
 }
 
 #[async_trait]
@@ -2549,7 +2562,7 @@ impl TableProvider for DataFrameTableProvider {
     }
 
     fn table_type(&self) -> TableType {
-        TableType::View
+        self.table_type
     }
 
     async fn scan(

datafusion/core/tests/dataframe/mod.rs

@@ -77,7 +77,7 @@ use datafusion_expr::var_provider::{VarProvider, VarType};
 use datafusion_expr::{
     cast, col, create_udf, exists, in_subquery, lit, out_ref_col, placeholder,
     scalar_subquery, when, wildcard, Expr, ExprFunctionExt, ExprSchemable, LogicalPlan,
-    LogicalPlanBuilder, ScalarFunctionImplementation, SortExpr, WindowFrame,
+    LogicalPlanBuilder, ScalarFunctionImplementation, SortExpr, TableType, WindowFrame,
     WindowFrameBound, WindowFrameUnits, WindowFunctionDefinition,
 };
 use datafusion_physical_expr::aggregate::AggregateExprBuilder;
@@ -1577,6 +1577,23 @@ async fn register_table() -> Result<()> {
     Ok(())
 }
 
+#[tokio::test]
+async fn register_temporary_table() -> Result<()> {
+    let df = test_table().await?.select_columns(&["c1", "c12"])?;
+    let ctx = SessionContext::new();
+    let df_impl = DataFrame::new(ctx.state(), df.logical_plan().clone());
+
+    let df_table_provider = df_impl.clone().into_temporary_view();
+
+    // check that we set the correct table_type
+    assert_eq!(df_table_provider.table_type(), TableType::Temporary);
+
+    // check that we can register a dataframe as a temporary table
+    ctx.register_table("test_table", df_table_provider)?;
+
+    Ok(())
+}
+
 /// Compare the formatted string representation of two plans for equality
 fn assert_same_plan(plan1: &LogicalPlan, plan2: &LogicalPlan) {
     assert_eq!(format!("{plan1:?}"), format!("{plan2:?}"));