safekeeper: remove .partial suffix on the last WAL file.

Reasons:
- it makes pg_waldump usage slightly more cumbersome, forcing to rename file.
- it makes pull_timeline slightly more cumbersome because at any
  moment source file can be renamed from partial to full.

Leave ability to read .partial files for backward compatibility.

libs/utils/scripts/restore_from_wal.sh

@@ -17,6 +17,5 @@ declare -i WAL_SIZE=$REDO_POS+114
 "$PG_BIN"/pg_ctl -D "$DATA_DIR" -l "$DATA_DIR/logfile.log" stop -m immediate
 cp "$DATA_DIR"/pg_wal/000000010000000000000001 .
 cp "$WAL_PATH"/* "$DATA_DIR"/pg_wal/
-for partial in "$DATA_DIR"/pg_wal/*.partial ; do mv "$partial" "${partial%.partial}" ; done
 dd if=000000010000000000000001 of="$DATA_DIR"/pg_wal/000000010000000000000001 bs=$WAL_SIZE count=1 conv=notrunc
 rm -f 000000010000000000000001

libs/utils/scripts/restore_from_wal_initdb.sh

@@ -16,6 +16,5 @@ declare -i WAL_SIZE=$REDO_POS+114
 "$PG_BIN"/pg_ctl -D "$DATA_DIR" -l "$DATA_DIR/logfile.log" stop -m immediate
 cp "$DATA_DIR"/pg_wal/000000010000000000000001 .
 cp "$WAL_PATH"/* "$DATA_DIR"/pg_wal/
-for partial in "$DATA_DIR"/pg_wal/*.partial ; do mv "$partial" "${partial%.partial}" ; done
 dd if=000000010000000000000001 of="$DATA_DIR"/pg_wal/000000010000000000000001 bs=$WAL_SIZE count=1 conv=notrunc
 rm -f 000000010000000000000001

safekeeper/src/wal_backup.rs

@@ -469,16 +469,33 @@ async fn backup_object(
         .await
 }
 
+/// Source file should point to path with segment without .partial suffix; we'll
+/// try to append .partial if file without it doesn't exist.
 pub(crate) async fn backup_partial_segment(
     source_file: &Utf8Path,
     target_file: &RemotePath,
     size: usize,
 ) -> Result<()> {
-    let storage = get_configured_remote_storage();
-
-    let file = File::open(&source_file)
-        .await
-        .with_context(|| format!("Failed to open file {source_file:?} for wal backup"))?;
+    let storage: &GenericRemoteStorage = get_configured_remote_storage();
+    let mut partial_path = source_file.to_owned();
+    partial_path.set_extension("partial");
+
+    // First try opening without .partial prefix, if that fails, open legacy .partial one.
+    let file = match File::open(&source_file).await {
+        Ok(file) => file,
+        Err(full_e) => match File::open(&partial_path).await {
+            Ok(file) => file,
+            Err(partial_e) => {
+                anyhow::bail!(
+                    "failed to open file for partial backup, {} error: '{}', {} error: '{}'",
+                    source_file,
+                    full_e,
+                    partial_path,
+                    partial_e
+                );
+            }
+        },
+    };
 
     // limiting the file to read only the first `size` bytes
     let limited_file = tokio::io::AsyncReadExt::take(file, size as u64);

safekeeper/src/wal_backup_partial.rs

@@ -117,10 +117,6 @@ impl PartialBackup {
             self.conf.my_id.0,
         )
     }
-
-    fn local_segment_name(&self, segno: u64) -> String {
-        format!("{}.partial", self.segment_name(segno))
-    }
 }
 
 impl PartialBackup {
@@ -152,7 +148,7 @@ impl PartialBackup {
         // We're going to backup bytes from the start of the segment up to flush_lsn.
         let backup_bytes = flush_lsn.segment_offset(self.wal_seg_size);
 
-        let local_path = self.local_prefix.join(self.local_segment_name(segno));
+        let local_path = self.local_prefix.join(self.segment_name(segno));
         let remote_path = RemotePath::new(self.remote_prefix.join(&prepared.name).as_ref())?;
 
         // Upload first `backup_bytes` bytes of the segment to the remote storage.

safekeeper/src/wal_storage.rs

@@ -3,9 +3,9 @@
 //! Safekeeper WAL is stored in the timeline directory, in format similar to pg_wal.
 //! PG timeline is always 1, so WAL segments are usually have names like this:
 //! - 000000010000000000000001
-//! - 000000010000000000000002.partial
+//! - 000000010000000000000002
 //!
-//! Note that last file has `.partial` suffix, that's different from postgres.
+//! In the past last file had `.partial` suffix, so code still can read it.
 
 use anyhow::{bail, Context, Result};
 use bytes::Bytes;
@@ -102,11 +102,13 @@ pub struct PhysicalStorage {
 
     /// Cached open file for the last segment.
     ///
-    /// If Some(file) is open, then it always:
-    /// - has ".partial" suffix
+    /// If Some(file, is_partial) is open, then it always:
     /// - points to write_lsn, so no seek is needed for writing
     /// - doesn't point to the end of the segment
-    file: Option<File>,
+    ///
+    /// If the file name has .partial suffix (created before suffix was
+    /// removed), the bool is True.
+    file: Option<(File, bool)>,
 
     /// When false, we have just initialized storage using the LSN from find_end_of_wal().
     /// In this case, [`write_lsn`] can be less than actually written WAL on disk. In particular,
@@ -243,29 +245,26 @@ impl PhysicalStorage {
 
             // Note: this doesn't get into observe_flush_seconds metric. But
             // segment init should be separate metric, if any.
-            if let Err(e) =
-                durable_rename(&tmp_path, &wal_file_partial_path, !self.conf.no_sync).await
-            {
+            if let Err(e) = durable_rename(&tmp_path, &wal_file_path, !self.conf.no_sync).await {
                 // Probably rename succeeded, but fsync of it failed. Remove
                 // the file then to avoid using it.
-                remove_file(wal_file_partial_path)
+                remove_file(wal_file_path)
                     .await
                     .or_else(utils::fs_ext::ignore_not_found)?;
                 return Err(e.into());
             }
-            Ok((file, true))
+            Ok((file, false))
         }
     }
 
     /// Write WAL bytes, which are known to be located in a single WAL segment.
     async fn write_in_segment(&mut self, segno: u64, xlogoff: usize, buf: &[u8]) -> Result<()> {
-        let mut file = if let Some(file) = self.file.take() {
-            file
+        let (mut file, is_partial) = if let Some((file, is_partial)) = self.file.take() {
+            (file, is_partial)
         } else {
             let (mut file, is_partial) = self.open_or_create(segno).await?;
-            assert!(is_partial, "unexpected write into non-partial segment file");
             file.seek(SeekFrom::Start(xlogoff as u64)).await?;
-            file
+            (file, is_partial)
         };
 
         file.write_all(buf).await?;
@@ -278,13 +277,15 @@ impl PhysicalStorage {
             // If we reached the end of a WAL segment, flush and close it.
             self.fdatasync_file(&file).await?;
 
-            // Rename partial file to completed file
-            let (wal_file_path, wal_file_partial_path) =
-                wal_file_paths(&self.timeline_dir, segno, self.wal_seg_size)?;
-            fs::rename(wal_file_partial_path, wal_file_path).await?;
+            // Rename partial file to completed file in case it was legacy .partial file.
+            if is_partial {
+                let (wal_file_path, wal_file_partial_path) =
+                    wal_file_paths(&self.timeline_dir, segno, self.wal_seg_size)?;
+                fs::rename(wal_file_partial_path, wal_file_path).await?;
+            }
         } else {
             // otherwise, file can be reused later
-            self.file = Some(file);
+            self.file = Some((file, is_partial));
         }
 
         Ok(())
@@ -298,7 +299,7 @@ impl PhysicalStorage {
     async fn write_exact(&mut self, pos: Lsn, mut buf: &[u8]) -> Result<()> {
         if self.write_lsn != pos {
             // need to flush the file before discarding it
-            if let Some(file) = self.file.take() {
+            if let Some((file, _)) = self.file.take() {
                 self.fdatasync_file(&file).await?;
             }
 
@@ -402,9 +403,9 @@ impl Storage for PhysicalStorage {
             return Ok(());
         }
 
-        if let Some(unflushed_file) = self.file.take() {
+        if let Some((unflushed_file, is_partial)) = self.file.take() {
             self.fdatasync_file(&unflushed_file).await?;
-            self.file = Some(unflushed_file);
+            self.file = Some((unflushed_file, is_partial));
         } else {
             // We have unflushed data (write_lsn != flush_lsn), but no file.
             // This should only happen if last file was fully written and flushed,
@@ -445,7 +446,7 @@ impl Storage for PhysicalStorage {
         }
 
         // Close previously opened file, if any
-        if let Some(unflushed_file) = self.file.take() {
+        if let Some((unflushed_file, _)) = self.file.take() {
             self.fdatasync_file(&unflushed_file).await?;
         }
 
@@ -455,20 +456,13 @@ impl Storage for PhysicalStorage {
         // Remove all segments after the given LSN.
         remove_segments_from_disk(&self.timeline_dir, self.wal_seg_size, |x| x > segno).await?;
 
-        let (mut file, is_partial) = self.open_or_create(segno).await?;
+        let (mut file, _) = self.open_or_create(segno).await?;
 
         // Fill end with zeroes
         file.seek(SeekFrom::Start(xlogoff as u64)).await?;
         write_zeroes(&mut file, self.wal_seg_size - xlogoff).await?;
         self.fdatasync_file(&file).await?;
 
-        if !is_partial {
-            // Make segment partial once again
-            let (wal_file_path, wal_file_partial_path) =
-                wal_file_paths(&self.timeline_dir, segno, self.wal_seg_size)?;
-            fs::rename(wal_file_path, wal_file_partial_path).await?;
-        }
-
         // Update LSNs
         self.write_lsn = end_pos;
         self.write_record_lsn = end_pos;

test_runner/regress/test_pg_waldump.py

@@ -1,5 +1,4 @@
 import os
-import shutil
 
 from fixtures.neon_fixtures import NeonEnv, PgBin
 from fixtures.utils import subprocess_capture
@@ -48,14 +47,13 @@ def test_pg_waldump(neon_simple_env: NeonEnv, test_output_dir, pg_bin: PgBin):
     endpoint.stop()
 
     assert endpoint.pgdata_dir
-    wal_path = os.path.join(endpoint.pgdata_dir, "pg_wal/000000010000000000000001")
+    seg_path = os.path.join(endpoint.pgdata_dir, "pg_wal/000000010000000000000001")
     pg_waldump_path = os.path.join(pg_bin.pg_bin_path, "pg_waldump")
     # check segment on compute
-    check_wal_segment(pg_waldump_path, wal_path, test_output_dir)
+    check_wal_segment(pg_waldump_path, seg_path, test_output_dir)
 
-    # Check file on safekeepers as well. pg_waldump is strict about file naming, so remove .partial suffix.
+    # Check file on safekeepers as well.
     sk = env.safekeepers[0]
     sk_tli_dir = sk.timeline_dir(tenant_id, timeline_id)
-    non_partial_path = os.path.join(sk_tli_dir, "000000010000000000000001")
-    shutil.copyfile(os.path.join(sk_tli_dir, "000000010000000000000001.partial"), non_partial_path)
-    check_wal_segment(pg_waldump_path, non_partial_path, test_output_dir)
+    seg_path = os.path.join(sk_tli_dir, "000000010000000000000001")
+    check_wal_segment(pg_waldump_path, seg_path, test_output_dir)

test_runner/regress/test_wal_acceptor.py

@@ -592,9 +592,9 @@ def test_s3_wal_replay(neon_env_builder: NeonEnvBuilder):
     # save the last (partial) file to put it back after recreation; others will be fetched from s3
     sk = env.safekeepers[0]
     tli_dir = Path(sk.data_dir()) / str(tenant_id) / str(timeline_id)
-    f_partial = Path([f for f in os.listdir(tli_dir) if f.endswith(".partial")][0])
+    f_partial = sk.list_segments(tenant_id, timeline_id)[-1]
     f_partial_path = tli_dir / f_partial
-    f_partial_saved = Path(sk.data_dir()) / f_partial.name
+    f_partial_saved = Path(sk.data_dir()) / f_partial
     f_partial_path.rename(f_partial_saved)
 
     pg_version = sk.http_client().timeline_status(tenant_id, timeline_id).pg_version