From 6938e16444a37747d74bdbde86269ea0fa7c1b09 Mon Sep 17 00:00:00 2001
From: Marc Prud'hommeaux <marc@prux.org>
Date: Mon, 8 Feb 2021 11:26:57 -0500
Subject: [PATCH 1/4] Add deregister_table

---
 rust/datafusion/src/execution/context.rs | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/rust/datafusion/src/execution/context.rs b/rust/datafusion/src/execution/context.rs
index 4b8a4f71fe62..9fb3a0d68fb4 100644
--- a/rust/datafusion/src/execution/context.rs
+++ b/rust/datafusion/src/execution/context.rs
@@ -287,6 +287,21 @@ impl ExecutionContext {
             .insert(name.to_string(), provider.into());
     }
 
+    /// Deregisters the named table.
+    /// 
+    /// Returns true if the table was successfully de-reregistered.
+    pub fn deregister_table(
+        &mut self,
+        name: &str
+    ) -> bool {
+        self.state
+            .lock()
+            .unwrap()
+            .datasources
+            .remove(&name.to_string())
+            .is_some()
+    }
+
     /// Retrieves a DataFrame representing a table previously registered by calling the
     /// register_table function.
     ///
@@ -720,6 +735,9 @@ mod tests {
         ];
         assert_batches_eq!(expected, &results);
 
+        assert_eq!(ctx.deregister_table("dual"), true);
+        assert_eq!(ctx.deregister_table("dual"), false);
+
         Ok(())
     }
 
@@ -1668,6 +1686,8 @@ mod tests {
             assert_eq!(a.value(i) + b.value(i), sum.value(i));
         }
 
+        ctx.deregister_table("t");
+
         Ok(())
     }
 

From 1e14c4fc385cf2c9f9d54c71e7568cc6ef69fd8d Mon Sep 17 00:00:00 2001
From: Marc Prud'hommeaux <marc@prux.org>
Date: Mon, 8 Feb 2021 11:56:09 -0500
Subject: [PATCH 2/4] Update context.rs

---
 rust/datafusion/src/execution/context.rs | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/rust/datafusion/src/execution/context.rs b/rust/datafusion/src/execution/context.rs
index 9fb3a0d68fb4..fdfbe9cc85b9 100644
--- a/rust/datafusion/src/execution/context.rs
+++ b/rust/datafusion/src/execution/context.rs
@@ -288,12 +288,9 @@ impl ExecutionContext {
     }
 
     /// Deregisters the named table.
-    /// 
+    ///
     /// Returns true if the table was successfully de-reregistered.
-    pub fn deregister_table(
-        &mut self,
-        name: &str
-    ) -> bool {
+    pub fn deregister_table(&mut self, name: &str) -> bool {
         self.state
             .lock()
             .unwrap()

From 5538aea9e1ded843fb226444a8845ef265319c26 Mon Sep 17 00:00:00 2001
From: Marc Prud'hommeaux <marc@prux.org>
Date: Mon, 8 Feb 2021 12:00:48 -0500
Subject: [PATCH 3/4] Update context.rs

---
 rust/datafusion/src/execution/context.rs | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/rust/datafusion/src/execution/context.rs b/rust/datafusion/src/execution/context.rs
index fdfbe9cc85b9..6bae96ca1522 100644
--- a/rust/datafusion/src/execution/context.rs
+++ b/rust/datafusion/src/execution/context.rs
@@ -732,6 +732,18 @@ mod tests {
         ];
         assert_batches_eq!(expected, &results);
 
+        Ok(())
+    }
+    
+    #[tokio::test]
+    async fn register_deregister() -> Result<()> {
+        let tmp_dir = TempDir::new()?;
+        let partition_count = 4;
+        let mut ctx = create_ctx(&tmp_dir, partition_count)?;
+
+        let provider = test::create_table_dual();
+        ctx.register_table("dual", provider);
+
         assert_eq!(ctx.deregister_table("dual"), true);
         assert_eq!(ctx.deregister_table("dual"), false);
 

From 58a1f6cbc7ae2abdddcfeb134d1c0361ca20c85d Mon Sep 17 00:00:00 2001
From: Marc Prud'hommeaux <marc@prux.org>
Date: Mon, 8 Feb 2021 12:46:54 -0500
Subject: [PATCH 4/4] Update context.rs

---
 rust/datafusion/src/execution/context.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/rust/datafusion/src/execution/context.rs b/rust/datafusion/src/execution/context.rs
index 6bae96ca1522..766d74ed58ef 100644
--- a/rust/datafusion/src/execution/context.rs
+++ b/rust/datafusion/src/execution/context.rs
@@ -734,7 +734,7 @@ mod tests {
 
         Ok(())
     }
-    
+
     #[tokio::test]
     async fn register_deregister() -> Result<()> {
         let tmp_dir = TempDir::new()?;