feat: Add remove_optimizer_rule to SessionContext (#19209)

## Which issue does this PR close?

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- Closes #19116.

## Rationale for this change

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in the issue then this section is not needed.
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Adds the ability to remove logical optimizer rules from the
`SessionContext` on the fly, without having to create a new one.
Together with the existing `add_optimizer_rule` we can now freely add
and remove rules.


## What changes are included in this PR?

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is sometimes worth providing a summary of the individual changes in this
PR.
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- Added `remove_optimizer_rule` to `SessionContext`.
- Added `remove_optimizer_rule` to `SessionState`.
- Added a unit test.

## Are these changes tested?

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Yes.

## Are there any user-facing changes?

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New optional method.

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

Author: nuno-faria

datafusion/core/src/execution/context/mod.rs

@@ -482,6 +482,11 @@ impl SessionContext {
         self.state.write().append_optimizer_rule(optimizer_rule);
     }
 
+    /// Removes an optimizer rule by name, returning `true` if it existed.
+    pub fn remove_optimizer_rule(&self, name: &str) -> bool {
+        self.state.write().remove_optimizer_rule(name)
+    }
+
     /// Adds an analyzer rule to the end of the existing rules.
     ///
     /// See [`SessionState`] for more control of when the rule is applied.
@@ -2609,4 +2614,49 @@ mod tests {
             }
         }
     }
+
+    #[tokio::test]
+    async fn remove_optimizer_rule() -> Result<()> {
+        let get_optimizer_rules = |ctx: &SessionContext| {
+            ctx.state()
+                .optimizer()
+                .rules
+                .iter()
+                .map(|r| r.name().to_owned())
+                .collect::<HashSet<_>>()
+        };
+
+        let ctx = SessionContext::new();
+        assert!(get_optimizer_rules(&ctx).contains("simplify_expressions"));
+
+        // default plan
+        let plan = ctx
+            .sql("select 1 + 1")
+            .await?
+            .into_optimized_plan()?
+            .to_string();
+        assert_snapshot!(plan, @r"
+        Projection: Int64(2) AS Int64(1) + Int64(1)
+          EmptyRelation: rows=1
+        ");
+
+        assert!(ctx.remove_optimizer_rule("simplify_expressions"));
+        assert!(!get_optimizer_rules(&ctx).contains("simplify_expressions"));
+
+        // plan without the simplify_expressions rule
+        let plan = ctx
+            .sql("select 1 + 1")
+            .await?
+            .into_optimized_plan()?
+            .to_string();
+        assert_snapshot!(plan, @r"
+        Projection: Int64(1) + Int64(1)
+          EmptyRelation: rows=1
+        ");
+
+        // attempting to remove a non-existing rule returns false
+        assert!(!ctx.remove_optimizer_rule("simplify_expressions"));
+
+        Ok(())
+    }
 }

datafusion/core/src/execution/session_state.rs

@@ -347,6 +347,13 @@ impl SessionState {
         self.optimizer.rules.push(optimizer_rule);
     }
 
+    /// Removes an optimizer rule by name, returning `true` if it existed.
+    pub(crate) fn remove_optimizer_rule(&mut self, name: &str) -> bool {
+        let original_len = self.optimizer.rules.len();
+        self.optimizer.rules.retain(|r| r.name() != name);
+        self.optimizer.rules.len() < original_len
+    }
+
     /// Registers a [`FunctionFactory`] to handle `CREATE FUNCTION` statements
     pub fn set_function_factory(&mut self, function_factory: Arc<dyn FunctionFactory>) {
         self.function_factory = Some(function_factory);