From c058e1cec2df70505263b19ad4e1f337d9643285 Mon Sep 17 00:00:00 2001
From: Arseny Sher <sher-ars@yandex.ru>
Date: Tue, 6 Jun 2023 15:27:17 +0400
Subject: [PATCH] Quick exit in truncate_wal if nothing to do.

ref https://github.com/neondatabase/neon/issues/4414
---
 safekeeper/src/wal_storage.rs | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/safekeeper/src/wal_storage.rs b/safekeeper/src/wal_storage.rs
index 1b82bd754e..644c956fc1 100644
--- a/safekeeper/src/wal_storage.rs
+++ b/safekeeper/src/wal_storage.rs
@@ -379,6 +379,12 @@ impl Storage for PhysicalStorage {
             );
         }
 
+        // Quick exit if nothing to do to avoid writing up to 16 MiB of zeros on
+        // disk (this happens on each connect).
+        if end_pos == self.write_lsn {
+            return Ok(());
+        }
+
         // Close previously opened file, if any
         if let Some(mut unflushed_file) = self.file.take() {
             self.fdatasync_file(&mut unflushed_file)?;