diff --git a/python/cocoindex/cli.py b/python/cocoindex/cli.py
index b5bdb762f..3bff88d22 100644
--- a/python/cocoindex/cli.py
+++ b/python/cocoindex/cli.py
@@ -49,20 +49,20 @@ def setup(delete_legacy_flows):
 @click.argument("flow_name", type=str, required=False)
 @click.option(
     "-L", "--live", is_flag=True, show_default=True, default=False,
-    help="If true, it will continuously watch changes from data sources and apply to the target index.")
-def update(flow_name: str | None, live: bool):
+    help="Continuously watch changes from data sources and apply to the target index.")
+@click.option(
+    "-q", "--quiet", is_flag=True, show_default=True, default=False,
+    help="Avoid printing anything to the output, e.g. statistics.")
+def update(flow_name: str | None, live: bool, quiet: bool):
     """
     Update the index to reflect the latest data from data sources.
     """
     async def _update_all():
         async def _update_flow(fl: flow.Flow):
-            updater = flow.FlowLiveUpdater(fl, flow.FlowLiveUpdaterOptions(live_mode=live))
+            updater = flow.FlowLiveUpdater(
+                fl,
+                flow.FlowLiveUpdaterOptions(live_mode=live, print_stats=not quiet))
             await updater.wait()
-            print(f"Updated index for {fl.name}:")
-            for line in str(updater.update_stats()).split("\n"):
-                if line := line.strip():
-                    print(f"  {line}")
-            print()
         await asyncio.gather(*(_update_flow(fl) for fl in _flows_by_name(flow_name)))
     asyncio.run(_update_all())
 
diff --git a/python/cocoindex/flow.py b/python/cocoindex/flow.py
index ca1dddb68..8f4ee45fd 100644
--- a/python/cocoindex/flow.py
+++ b/python/cocoindex/flow.py
@@ -370,6 +370,7 @@ class FlowLiveUpdaterOptions:
     Options for live updating a flow.
     """
     live_mode: bool = False
+    print_stats: bool = False
 
 class FlowLiveUpdater:
     """
diff --git a/src/execution/live_updater.rs b/src/execution/live_updater.rs
index 4b4eb020a..f54603eba 100644
--- a/src/execution/live_updater.rs
+++ b/src/execution/live_updater.rs
@@ -17,6 +17,9 @@ pub struct FlowLiveUpdaterOptions {
     /// If true, the updater will keep refreshing the index.
     /// Otherwise, it will only apply changes from the source up to the current time.
     pub live_mode: bool,
+
+    /// If true, stats will be printed to the console.
+    pub print_stats: bool,
 }
 
 async fn update_source(
@@ -25,18 +28,38 @@ async fn update_source(
     source_update_stats: Arc<stats::UpdateStats>,
     source_idx: usize,
     pool: PgPool,
-    live_mode: bool,
+    options: FlowLiveUpdaterOptions,
 ) -> Result<()> {
     let source_context = flow_ctx
         .get_source_indexing_context(source_idx, &pool)
         .await?;
 
+    let import_op = &plan.import_ops[source_idx];
+    let maybe_print_stats = |stats: &stats::UpdateStats| {
+        if options.print_stats {
+            println!(
+                "{}.{}: {}",
+                flow_ctx.flow.flow_instance.name, import_op.name, stats
+            );
+        } else {
+            trace!(
+                "{}.{}: {}",
+                flow_ctx.flow.flow_instance.name,
+                import_op.name,
+                stats
+            );
+        }
+    };
+
     let mut update_start = Instant::now();
     source_context.update(&pool, &source_update_stats).await?;
+    maybe_print_stats(&source_update_stats);
 
-    let import_op = &plan.import_ops[source_idx];
-    if let (true, Some(refresh_interval)) = (live_mode, import_op.refresh_options.refresh_interval)
-    {
+    if let (true, Some(refresh_interval)) = (
+        options.live_mode,
+        import_op.refresh_options.refresh_interval,
+    ) {
+        let mut last_stats = source_update_stats.as_ref().clone();
         loop {
             let elapsed = update_start.elapsed();
             if elapsed < refresh_interval {
@@ -44,6 +67,10 @@ async fn update_source(
             }
             update_start = Instant::now();
             source_context.update(&pool, &source_update_stats).await?;
+
+            let this_stats = source_update_stats.as_ref().clone();
+            maybe_print_stats(&this_stats.delta(&last_stats));
+            last_stats = this_stats;
         }
     }
     Ok(())
@@ -67,7 +94,7 @@ impl FlowLiveUpdater {
                     source_update_stats.clone(),
                     source_idx,
                     pool.clone(),
-                    options.live_mode,
+                    options.clone(),
                 ));
                 source_update_stats
             })
diff --git a/src/execution/row_indexer.rs b/src/execution/row_indexer.rs
index d5c48f262..d3827cade 100644
--- a/src/execution/row_indexer.rs
+++ b/src/execution/row_indexer.rs
@@ -3,7 +3,6 @@ use crate::prelude::*;
 use futures::future::try_join_all;
 use sqlx::PgPool;
 use std::collections::{HashMap, HashSet};
-use std::sync::atomic::Ordering::Relaxed;
 
 use super::db_tracking::{self, read_source_tracking_info_for_processing, TrackedTargetKey};
 use super::db_tracking_setup;
@@ -101,7 +100,7 @@ impl SourceVersion {
         };
         if should_skip {
             if let Some(update_stats) = update_stats {
-                update_stats.num_skipped.fetch_add(1, Relaxed);
+                update_stats.num_skipped.inc(1);
             }
         }
         should_skip
@@ -585,12 +584,12 @@ pub async fn update_source_row(
 
     if already_exists {
         if output.is_some() {
-            update_stats.num_repreocesses.fetch_add(1, Relaxed);
+            update_stats.num_repreocesses.inc(1);
         } else {
-            update_stats.num_deletions.fetch_add(1, Relaxed);
+            update_stats.num_deletions.inc(1);
         }
     } else if output.is_some() {
-        update_stats.num_insertions.fetch_add(1, Relaxed);
+        update_stats.num_insertions.inc(1);
     }
 
     Ok(SkippedOr::Normal(()))
diff --git a/src/execution/stats.rs b/src/execution/stats.rs
index 8db36aed0..a2943068f 100644
--- a/src/execution/stats.rs
+++ b/src/execution/stats.rs
@@ -1,46 +1,94 @@
 use crate::prelude::*;
 
-use std::sync::atomic::{AtomicUsize, Ordering::Relaxed};
+use std::{
+    ops::AddAssign,
+    sync::atomic::{AtomicI64, Ordering::Relaxed},
+};
 
-#[derive(Debug, Serialize, Default)]
-pub struct UpdateStats {
-    pub num_skipped: AtomicUsize,
-    pub num_insertions: AtomicUsize,
-    pub num_deletions: AtomicUsize,
-    pub num_repreocesses: AtomicUsize,
-    pub num_errors: AtomicUsize,
+#[derive(Default, Serialize)]
+pub struct Counter(pub AtomicI64);
+
+impl Counter {
+    pub fn inc(&self, by: i64) {
+        self.0.fetch_add(by, Relaxed);
+    }
+
+    pub fn get(&self) -> i64 {
+        self.0.load(Relaxed)
+    }
+
+    pub fn delta(&self, base: &Self) -> Counter {
+        Counter(AtomicI64::new(self.get() - base.get()))
+    }
+
+    pub fn into_inner(self) -> i64 {
+        self.0.into_inner()
+    }
+}
+
+impl AddAssign for Counter {
+    fn add_assign(&mut self, rhs: Self) {
+        self.0.fetch_add(rhs.into_inner(), Relaxed);
+    }
 }
 
-impl Clone for UpdateStats {
+impl Clone for Counter {
     fn clone(&self) -> Self {
-        Self {
-            num_skipped: self.num_skipped.load(Relaxed).into(),
-            num_insertions: self.num_insertions.load(Relaxed).into(),
-            num_deletions: self.num_deletions.load(Relaxed).into(),
-            num_repreocesses: self.num_repreocesses.load(Relaxed).into(),
-            num_errors: self.num_errors.load(Relaxed).into(),
+        Self(AtomicI64::new(self.get()))
+    }
+}
+
+impl std::fmt::Display for Counter {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{}", self.get())
+    }
+}
+
+impl std::fmt::Debug for Counter {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{}", self.get())
+    }
+}
+
+#[derive(Debug, Serialize, Default, Clone)]
+pub struct UpdateStats {
+    pub num_skipped: Counter,
+    pub num_insertions: Counter,
+    pub num_deletions: Counter,
+    pub num_repreocesses: Counter,
+    pub num_errors: Counter,
+}
+
+impl UpdateStats {
+    pub fn delta(&self, base: &Self) -> Self {
+        UpdateStats {
+            num_skipped: self.num_skipped.delta(&base.num_skipped),
+            num_insertions: self.num_insertions.delta(&base.num_insertions),
+            num_deletions: self.num_deletions.delta(&base.num_deletions),
+            num_repreocesses: self.num_repreocesses.delta(&base.num_repreocesses),
+            num_errors: self.num_errors.delta(&base.num_errors),
         }
     }
 }
 
 impl std::fmt::Display for UpdateStats {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        let num_skipped = self.num_skipped.load(Relaxed);
+        let num_skipped = self.num_skipped.get();
         if num_skipped > 0 {
             write!(f, "{} rows skipped", num_skipped)?;
         }
 
-        let num_insertions = self.num_insertions.load(Relaxed);
-        let num_deletions = self.num_deletions.load(Relaxed);
-        let num_reprocesses = self.num_repreocesses.load(Relaxed);
+        let num_insertions = self.num_insertions.get();
+        let num_deletions = self.num_deletions.get();
+        let num_reprocesses = self.num_repreocesses.get();
         let num_source_rows = num_insertions + num_deletions + num_reprocesses;
         if num_source_rows > 0 {
             if num_skipped > 0 {
-                write!(f, ", ")?;
+                write!(f, "; ")?;
             }
             write!(f, "{num_source_rows} source rows processed",)?;
 
-            let num_errors = self.num_errors.load(Relaxed);
+            let num_errors = self.num_errors.get();
             if num_errors > 0 {
                 write!(f, " with {num_errors} ERRORS",)?;
             }
diff --git a/src/service/flows.rs b/src/service/flows.rs
index 1179c582f..b65398af9 100644
--- a/src/service/flows.rs
+++ b/src/service/flows.rs
@@ -174,7 +174,10 @@ pub async fn update(
     let mut live_updater = execution::FlowLiveUpdater::start(
         flow_ctx.clone(),
         &lib_context.pool,
-        execution::FlowLiveUpdaterOptions { live_mode: false },
+        execution::FlowLiveUpdaterOptions {
+            live_mode: false,
+            ..Default::default()
+        },
     )
     .await?;
     live_updater.wait().await?;