Expose a get_mv_candidates_for_table API for ViewMatcher (#112)

* Expose a get_mv_candidates_for_table API for ViewMatcher

* refine comments

Author: xudong963

src/rewrite/exploitation.rs

@@ -119,6 +119,43 @@ impl ViewMatcher {
     pub fn mv_plans(&self) -> &HashMap<TableReference, (Arc<dyn TableProvider>, SpjNormalForm)> {
         &self.mv_plans
     }
+
+    /// Returns materialized views that potentially reference the given table.
+    ///
+    /// This is a preliminary filter - it only checks if the MV references the table
+    /// but does NOT guarantee that the MV can actually be used to rewrite queries
+    /// involving that table.
+    ///
+    /// # Arguments
+    ///
+    /// * `table_reference` - The table reference to find candidates for
+    ///
+    /// # Returns
+    ///
+    /// A vector of tuples containing:
+    /// - The materialized view's table reference
+    /// - The materialized view's table provider
+    /// - The materialized view's SPJ normal form
+    pub fn get_potential_mv_candidates_for_table(
+        &self,
+        table_reference: &TableReference,
+    ) -> Vec<(TableReference, Arc<dyn TableProvider>, &SpjNormalForm)> {
+        self.mv_plans
+            .iter()
+            .filter_map(|(mv_table_ref, (mv_provider, mv_normal_form))| {
+                // Check if this MV references the target table
+                if mv_normal_form.referenced_tables().contains(table_reference) {
+                    Some((
+                        mv_table_ref.clone(),
+                        Arc::clone(mv_provider),
+                        mv_normal_form,
+                    ))
+                } else {
+                    None
+                }
+            })
+            .collect()
+    }
 }
 
 impl OptimizerRule for ViewMatcher {