feat(pg_dump): Add '--if-exists' option for pg_dump (#478)

Author: DmytroLitvinov

dbbackup/db/postgresql.py

@@ -100,6 +100,7 @@ class PgDumpBinaryConnector(PgDumpConnector):
     restore_cmd = "pg_restore"
     single_transaction = True
     drop = True
+    if_exists = False
 
     def _create_dump(self):
         cmd = f"{self.dump_cmd} "
@@ -120,6 +121,8 @@ def _restore_dump(self, dump):
             cmd += " --single-transaction"
         if self.drop:
             cmd += " --clean"
+        if self.if_exists:
+            cmd += " --if-exists"
         cmd = f"{self.restore_prefix} {cmd} {self.restore_suffix}"
         stdout, stderr = self.run_command(cmd, stdin=dump, env=self.restore_env)
         return stdout, stderr

docs/databases.rst

@@ -166,6 +166,13 @@ This corresponds to ``--clean`` argument of ``pg_dump`` and ``pg_restore``.
 
 Default: ``True``
 
+IF_EXISTS
+~~~~
+
+Use DROP ... IF EXISTS commands to drop objects in ``--clean`` mode of ``pg_dump``.
+
+Default: ``False``
+
 PostGIS
 -------