Can't WAL or optimize read only databases

apsw/bestpractice.py

@@ -16,7 +16,10 @@ def connection_wal(connection: apsw.Connection) -> None:
     Reduces contention and improves write performance.  WAL is
     `described here <https://www.sqlite.org/wal.html>`__.
     """
-    connection.pragma("journal_mode", "wal")
+    try:
+        connection.pragma("journal_mode", "wal")
+    except apsw.ReadOnlyError:
+        pass
 
 
 def connection_busy_timeout(connection: apsw.Connection, duration_ms: int = 100) -> None:
@@ -70,7 +73,10 @@ def connection_optimize(connection: apsw.Connection) -> None:
     There is more detail in the `documentation
     <https://sqlite.org/lang_analyze.html>`__.
     """
-    connection.pragma("optimize", 0x10002)
+    try:
+        connection.pragma("optimize", 0x10002)
+    except apsw.ReadOnlyError:
+        pass
 
 def connection_recursive_triggers(connection: apsw.Connection) -> None:
     """Recursive triggers are off for historical backwards compatibility

apsw/tests.py

@@ -10132,6 +10132,9 @@ def testBestPractice(self) -> None:
             with self.assertNoLogs():
                 self.assertRaises(apsw.SQLError, con.execute, dqs)
 
+        # can't optimize or WAL readonly databases
+        apsw.Connection(self.db.filename, flags = apsw.SQLITE_OPEN_READONLY)
+
     def testExtDataClassRowFactory(self) -> None:
         "apsw.ext.DataClassRowFactory"
         dcrf = apsw.ext.DataClassRowFactory()