From d15116f2cc4b26ad36f9cf28c5cf9f9343269cc3 Mon Sep 17 00:00:00 2001
From: Arthur Petukhovsky <petuhovskiy@yandex.ru>
Date: Fri, 23 Sep 2022 14:36:08 +0000
Subject: [PATCH] Update pg_version for old timelines

---
 safekeeper/src/control_file_upgrade.rs | 12 ++++++++++++
 safekeeper/src/safekeeper.rs           |  3 +--
 safekeeper/src/timeline.rs             |  2 ++
 safekeeper/src/wal_storage.rs          | 16 +++++-----------
 4 files changed, 20 insertions(+), 13 deletions(-)

diff --git a/safekeeper/src/control_file_upgrade.rs b/safekeeper/src/control_file_upgrade.rs
index d8434efb20..1ce9186085 100644
--- a/safekeeper/src/control_file_upgrade.rs
+++ b/safekeeper/src/control_file_upgrade.rs
@@ -248,6 +248,18 @@ pub fn upgrade_control_file(buf: &[u8], version: u32) -> Result<SafeKeeperState>
         oldstate.timeline_start_lsn = Lsn(1);
         oldstate.local_start_lsn = Lsn(1);
 
+        return Ok(oldstate);
+    } else if version == 6 {
+        info!("reading safekeeper control file version {}", version);
+        let mut oldstate = SafeKeeperState::des(&buf[..buf.len()])?;
+        if oldstate.server.pg_version != 0 {
+            return Ok(oldstate);
+        }
+
+        // set pg_version to the default v14
+        info!("setting pg_version to 140005");
+        oldstate.server.pg_version = 140005;
+
         return Ok(oldstate);
     }
     bail!("unsupported safekeeper control file version {}", version)
diff --git a/safekeeper/src/safekeeper.rs b/safekeeper/src/safekeeper.rs
index eec24faf2f..7869aa8b3a 100644
--- a/safekeeper/src/safekeeper.rs
+++ b/safekeeper/src/safekeeper.rs
@@ -25,7 +25,7 @@ use utils::{
 };
 
 pub const SK_MAGIC: u32 = 0xcafeceefu32;
-pub const SK_FORMAT_VERSION: u32 = 6;
+pub const SK_FORMAT_VERSION: u32 = 7;
 const SK_PROTOCOL_VERSION: u32 = 2;
 pub const UNKNOWN_SERVER_VERSION: u32 = 0;
 
@@ -639,7 +639,6 @@ where
 
             let mut state = self.state.clone();
             state.server.system_id = msg.system_id;
-            state.server.wal_seg_size = msg.wal_seg_size;
             if msg.pg_version != UNKNOWN_SERVER_VERSION {
                 state.server.pg_version = msg.pg_version;
             }
diff --git a/safekeeper/src/timeline.rs b/safekeeper/src/timeline.rs
index c16fc9f40c..dc7503af65 100644
--- a/safekeeper/src/timeline.rs
+++ b/safekeeper/src/timeline.rs
@@ -314,6 +314,8 @@ impl Timeline {
         ttid: TenantTimelineId,
         wal_backup_launcher_tx: Sender<TenantTimelineId>,
     ) -> Result<Timeline> {
+        let _enter = info_span!("load_timeline", timeline = %ttid.timeline_id).entered();
+
         let shared_state = SharedState::restore(&conf, &ttid)?;
         let (commit_lsn_watch_tx, commit_lsn_watch_rx) =
             watch::channel(shared_state.sk.state.commit_lsn);
diff --git a/safekeeper/src/wal_storage.rs b/safekeeper/src/wal_storage.rs
index eee7c703f9..8fbd479d95 100644
--- a/safekeeper/src/wal_storage.rs
+++ b/safekeeper/src/wal_storage.rs
@@ -111,6 +111,10 @@ impl PhysicalStorage {
 
         // Find out where stored WAL ends, starting at commit_lsn which is a
         // known recent record boundary (unless we don't have WAL at all).
+        //
+        // NB: find_end_of_wal MUST be backwards compatible with the previously
+        // written WAL. If find_end_of_wal fails to read any WAL written by an
+        // older version of the code, we could lose data forever.
         let write_lsn = if state.commit_lsn == Lsn(0) {
             Lsn(0)
         } else {
@@ -125,17 +129,7 @@ impl PhysicalStorage {
                     wal_seg_size,
                     state.commit_lsn,
                 )?,
-                pg_majorversion => {
-                    // This is a quik hack to work with old timelines that don't have
-                    // pg_version in the control file. We can remove it after this is fixed properly.
-                    const DEFAULT_PG_MAJOR_VERSION: u32 = 14;
-                    warn!("unknown postgres version {pg_majorversion} assume {DEFAULT_PG_MAJOR_VERSION}");
-                    postgres_ffi::v14::xlog_utils::find_end_of_wal(
-                        &timeline_dir,
-                        wal_seg_size,
-                        state.commit_lsn,
-                    )?
-                }
+                _ => bail!("unsupported postgres version: {}", state.server.pg_version),
             }
         };