diff --git a/src/observability/simple_trace.rs b/src/observability/simple_trace.rs
index 6321ae5..9615ccb 100644
--- a/src/observability/simple_trace.rs
+++ b/src/observability/simple_trace.rs
@@ -97,6 +97,27 @@ impl SimpleTracer {
         }
         result
     }
+
+    pub fn push_tracer(&mut self, mut tracer: SimpleTracer) {
+        assert_eq!(tracer.open_spans.len(), 1);
+        let mut children = tracer.open_spans.pop().unwrap().children;
+        // Set depth of children to the depth of the current span + 1
+        for child in children.iter_mut() {
+            set_depth(child, self.open_spans.len());
+        }
+        self.open_spans.last_mut().unwrap().children.extend(children);
+    }
+
+    pub fn elapsed(&self) -> Duration {
+        self.open_spans.last().unwrap().start_time.elapsed()
+    }
+}
+
+fn set_depth(child: &mut SimpleSpan, depth: usize) {
+    child.depth = depth;
+    for child in child.children.iter_mut() {
+        set_depth(child, depth + 1);
+    }
 }
 
 impl SimpleSpan {
@@ -132,9 +153,9 @@ impl SimpleSpan {
             for (name, (total_duration, count)) in agg_spans {
                 let duration_str = format_duration(total_duration);
                 if count > 1 {
-                    result.push_str(&format!("{}: {} (× {})\n", name, duration_str, count));
+                    result.push_str(&format!("{}  {}: {} (×{})\n", indent, name, duration_str, count));
                 } else {
-                    result.push_str(&format!("{}: {}\n", name, duration_str));
+                    result.push_str(&format!("{}  {}: {}\n", indent, name, duration_str));
                 }
             }
         } else {
diff --git a/src/scheduler/inner_locustdb.rs b/src/scheduler/inner_locustdb.rs
index 382837d..112a986 100644
--- a/src/scheduler/inner_locustdb.rs
+++ b/src/scheduler/inner_locustdb.rs
@@ -36,6 +36,9 @@ use self::meta_store::SubpartitionMetadata;
 use self::raw_col::MixedCol;
 use self::wal_segment::WalSegment;
 
+// Table name + list of partitions
+pub type PartitionList = (String, Vec<(u64, String)>);
+
 pub struct InnerLocustDB {
     tables: RwLock<HashMap<String, Arc<Table>>>,
     lru: Lru,
@@ -400,11 +403,32 @@ impl InnerLocustDB {
             let tx = tx.clone();
             let this = self.clone();
             self.walflush_threadpool.execute(move || {
-                let to_delete = this.compact(table, id, range, &parts);
-                tx.send(to_delete).unwrap();
+                let (to_delete, tracer) = this.compact(table, id, range, &parts);
+                tx.send((to_delete, tracer)).unwrap();
             });
         }
-        let partitions_to_delete = rx.iter().take(num_compactions).flatten().collect();
+        let mut partitions_to_delete = vec![];
+        let mut longest_span: Option<(SimpleTracer, Duration)> = None;
+        for (to_delete, tracer) in rx.iter().take(num_compactions) {
+            if let Some(to_delete) = to_delete {
+                partitions_to_delete.push(to_delete);
+            }
+            let elapsed = tracer.elapsed();
+            if longest_span.is_none() || elapsed > longest_span.as_ref().unwrap().1 {
+                longest_span = Some((tracer, elapsed));
+            }
+        }
+        tracer.annotate("table_count", num_compactions);
+        tracer.annotate(
+            "partition_count",
+            partitions_to_delete
+                .iter()
+                .map(|(_, p)| p.len())
+                .sum::<usize>(),
+        );
+        if let Some((compaction_tracer, _)) = longest_span {
+            tracer.push_tracer(compaction_tracer);
+        }
         tracer.end_span(span_compaction);
 
         // Update metastore and clean up orphaned partitions and WAL segments
@@ -530,11 +554,14 @@ impl InnerLocustDB {
         id: PartitionID,
         range: Range<usize>,
         parts: &[u64],
-    ) -> Option<(String, Vec<(u64, String)>)> {
+    ) -> (Option<PartitionList>, SimpleTracer) {
         // get table, create new merged partition/sub-partitions (not registered with table)
         // - get names of all columns
         // - run query for each column, construct Column
         // - create subpartitions
+        let mut tracer = SimpleTracer::default();
+
+        let span_load_column_names = tracer.start_span("load_column_names");
         if !table.columns_names_loaded() {
             let column_names = self
                 .query_column_names(table.name())
@@ -542,10 +569,20 @@ impl InnerLocustDB {
             table.init_column_names(column_names.into_iter().collect());
         }
         let colnames = table.column_names();
+        tracer.end_span(span_load_column_names);
+
+        let span_snapshot_partitions = tracer.start_span("snapshot_partitions");
         let data = table.snapshot_parts(parts);
+        tracer.end_span(span_snapshot_partitions);
+
+        let span_load_columns = tracer.start_span("load_columns");
         let mut columns = Vec::with_capacity(colnames.len());
         for column in &colnames {
+            let span_create_query = tracer.start_span("create_query");
             let query = Query::read_column(table.name(), column);
+            tracer.end_span(span_create_query);
+
+            let span_schedule_query = tracer.start_span("schedule_query");
             let (sender, receiver) = oneshot::channel();
             let query_task = QueryTask::new(
                 query,
@@ -560,7 +597,13 @@ impl InnerLocustDB {
             )
             .unwrap();
             self.schedule(query_task);
+            tracer.end_span(span_schedule_query);
+
+            let span_block_on = tracer.start_span("await_query");
             let result = block_on(receiver).unwrap().unwrap();
+            tracer.end_span(span_block_on);
+
+            let span_column_builder = tracer.start_span("build_column");
             let mut column_builder = MixedCol::default();
             let column_data = result.columns.into_iter().next().unwrap().1;
             match column_data {
@@ -572,6 +615,8 @@ impl InnerLocustDB {
                     raws.into_iter().for_each(|r| column_builder.push(r))
                 }
             }
+            tracer.end_span(span_column_builder);
+
             assert_eq!(
                 range.len(),
                 column_builder.len(),
@@ -579,15 +624,25 @@ impl InnerLocustDB {
                 column_builder.len(),
                 table.name(),
             );
+
+            let span_finalize_column = tracer.start_span("finalize_column");
             columns.push(column_builder.finalize(column));
+            tracer.end_span(span_finalize_column);
         }
+        tracer.end_span(span_load_columns);
+
+        let span_subpartition = tracer.start_span("subpartition");
         let (metadata, subpartitions) = subpartition(&self.opts, columns.clone());
+        tracer.end_span(span_subpartition);
 
         // replace old partitions with new partition
+        let span_compact_partitions = tracer.start_span("compact_partitions");
         table.compact(id, range.start, columns, parts);
+        tracer.end_span(span_compact_partitions);
 
         // write new subpartitions to disk and update in-memory metastore
-        self.storage.as_ref().map(|s| {
+        let span_prepare_compact = tracer.start_span("prepare_compact");
+        let to_delete = self.storage.as_ref().map(|s| {
             let to_delete = s.prepare_compact(
                 table.name(),
                 id,
@@ -597,7 +652,10 @@ impl InnerLocustDB {
                 range.start,
             );
             (table.name().to_string(), to_delete)
-        })
+        });
+        tracer.end_span(span_prepare_compact);
+
+        (to_delete, tracer)
     }
 
     pub fn restore(&self, id: PartitionID, column: Column) {