Support PITR backups on PostgreSQL 15+

Author: natefoo

files/backup.py

@@ -33,8 +33,6 @@
 import psycopg2
 
 
-START_BACKUP_SQL = "SELECT pg_start_backup(%(label)s, false, false)"
-STOP_BACKUP_SQL = "SELECT * FROM pg_stop_backup(false, true)"
 RSYNC_EXCLUDES = (
     'pg_wal/*',  # >= 10
     'pg_xlog/*', # < 10
@@ -87,10 +85,26 @@ def __init__(self):
         self._cursor = None
         self._label = None
         self._rsync_opts = None
+        self._pg_major_version = None
 
     def set_rsync_opts(self, opts):
         self._rsync_opts = opts
 
+    @property
+    def pg_major_version(self):
+        if self._pg_major_version is None:
+            self.cursor.execute('SHOW server_version_num')
+            # server_version_num is an int in the format (major*10000)+minor for > 9.6 or
+            # (major*10000)+(minor*100)+patch for 9.6 and older.
+            version_int = self.cursor.fetchone()[0]
+            try:
+                self._pg_major_version = int(int(version_int) / 10000)
+                log.info("PostgreSQL server major version: %s", self._pg_major_version)
+            except:
+                log.error("Unable to parse PostgreSQL server_version: %s", version_int)
+                raise
+        return self._pg_major_version
+
     @property
     def rsync_cmd(self):
         cmd = ['rsync']
@@ -152,7 +166,11 @@ def log_command(cmd):
 
 def initiate_backup():
     log.info("Initiating backup with pg_start_backup()")
-    state.cursor.execute(START_BACKUP_SQL, {'label': state.label})
+    if state.pg_major_version < 15:
+        start_backup_sql = "SELECT pg_start_backup(%(label)s, false, false)"
+    else:
+        start_backup_sql = "SELECT pg_backup_start(%(label)s, false)"
+    state.cursor.execute(start_backup_sql, {'label': state.label})
 
 
 def perform_backup(backup_path, rsync_backup_opts):
@@ -193,7 +211,11 @@ def write_backup_file(backup_path, file_contents, file_name):
 
 def finalize_backup(backup_path):
     log.info("Finalizing backup with pg_stop_backup()")
-    state.cursor.execute(STOP_BACKUP_SQL)
+    if state.pg_major_version < 15:
+        stop_backup_sql = "SELECT * FROM pg_stop_backup(false, true)"
+    else:
+        stop_backup_sql = "SELECT * FROM pg_packup_stop(true)"
+    state.cursor.execute(stop_backup_sql)
     row = state.cursor.fetchone()
     last_segment = row[0]
     backup_label = row[1]