Creating a linked table from an MVStore database to a non-MVStore database…

Creating a linked table from an MVStore database to a non-MVStore database created a second (non-MVStore) database file.

h2/src/main/org/h2/engine/ConnectionInfo.java

@@ -248,7 +248,7 @@ public class ConnectionInfo implements Cloneable {
     }
 
     private void readSettingsFromURL() {
-        DbSettings dbSettings = DbSettings.getInstance(null);
+        DbSettings defaultSettings = DbSettings.getDefaultSettings();
         int idx = url.indexOf(';');
         if (idx >= 0) {
             String settings = url.substring(idx + 1);
@@ -265,7 +265,7 @@ public class ConnectionInfo implements Cloneable {
                 String value = setting.substring(equal + 1);
                 String key = setting.substring(0, equal);
                 key = StringUtils.toUpperEnglish(key);
-                if (!isKnownSetting(key) && !dbSettings.containsKey(key)) {
+                if (!isKnownSetting(key) && !defaultSettings.containsKey(key)) {
                     throw DbException.get(ErrorCode.UNSUPPORTED_SETTING_1, key);
                 }
                 String old = prop.getProperty(key);
@@ -639,14 +639,11 @@ public class ConnectionInfo implements Cloneable {
     }
 
     public DbSettings getDbSettings() {
-        DbSettings defaultSettings = DbSettings.getInstance(null);
-        HashMap<String, String> s = null;
+        DbSettings defaultSettings = DbSettings.getDefaultSettings();
+        HashMap<String, String> s = New.hashMap();
         for (Object k : prop.keySet()) {
             String key = k.toString();
             if (!isKnownSetting(key) && defaultSettings.containsKey(key)) {
-                if (s == null) {
-                    s = New.hashMap();
-                }
                 s.put(key, prop.getProperty(key));
             }
         }

h2/src/main/org/h2/engine/DbSettings.java

@@ -341,19 +341,26 @@ public class DbSettings extends SettingsBase {
 
     /**
      * INTERNAL.
-     * Get the settings for the given properties (may be null).
+     * Get the settings for the given properties (may not be null).
      *
      * @param s the settings
      * @return the settings
      */
     public static DbSettings getInstance(HashMap<String, String> s) {
-        if (s == null || s.isEmpty()) {
-            if (defaultSettings == null) {
-                defaultSettings = new DbSettings(new HashMap<String, String>());
-            }
-            return defaultSettings;
-        }
         return new DbSettings(s);
     }
+    
+    /**
+     * INTERNAL.
+     * Get the default settings. Those must not be modified.
+     *
+     * @return the settings
+     */
+    public static DbSettings getDefaultSettings() {
+        if (defaultSettings == null) {
+            defaultSettings = new DbSettings(new HashMap<String, String>());
+        }
+        return defaultSettings;
+    }
 
 }

h2/src/main/org/h2/engine/Engine.java

@@ -182,7 +182,7 @@ public class Engine implements SessionFactory {
             }
         }
         session.setAllowLiterals(true);
-        DbSettings defaultSettings = DbSettings.getInstance(null);
+        DbSettings defaultSettings = DbSettings.getDefaultSettings();
         for (String setting : ci.getKeys()) {
             if (defaultSettings.containsKey(setting)) {
                 // database setting are only used when opening the database