chore: add compactor logging detail (#7748)

compactor2/src/driver.rs

@@ -448,7 +448,10 @@ async fn execute_plan(
             .expect("semaphore not closed");
         info!(
             partition_id = partition_info.partition_id.get(),
-            permits, "job semaphore acquired",
+            column_count = partition_info.column_count(),
+            input_files = plan_ir.n_input_files(),
+            permits,
+            "job semaphore acquired",
         );
 
         let plan = components

compactor2/src/plan_ir.rs

@@ -60,6 +60,15 @@ impl PlanIR {
         }
     }
 
+    /// return the number of input files that will be compacted together
+    pub fn n_input_files(&self) -> usize {
+        match self {
+            Self::Compact { files, .. } => files.len(),
+            Self::Split { files, .. } => files.len(),
+            Self::None { .. } => 0,
+        }
+    }
+
     /// return the input files that will be compacted together
     pub fn input_files(&self) -> &[FileIR] {
         match self {