For read-only databases, for the trace level "debug", the trace info is written…

For read-only databases, for the trace level "debug", the trace info is written to the temp directory.

h2/src/docsrc/html/changelog.html

@@ -18,7 +18,10 @@ Change Log
 <h1>Change Log</h1>
 
 <h2>Next Version (unreleased)</h2>
-<ul><li>Closing the file lock will now wait until the background thread is stopped.
+<ul><li>The method TableEngine.createTable() now returns a Table object.
+</li><li>For read-only databases, for the trace level "debug",
+    the trace info is written to the temp directory.
+</li><li>Closing the file lock will now wait until the background thread is stopped.
 </li><li>In version 1.3.172, a performance regression was introduced when
     fixing the issue 389 (when there is a multi-column primary key, 
     H2 does not seem to always pick the right index). This was related to

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

@@ -534,7 +534,12 @@ public class Database implements DataHandler {
                 readOnly = true;
             }
             if (readOnly) {
-                traceSystem = new TraceSystem(null);
+                if (traceLevelFile >= TraceSystem.DEBUG) {
+                    String traceFile = Utils.getProperty("java.io.tmpdir", ".") + "/" + "h2_" + System.currentTimeMillis();
+                    traceSystem = new TraceSystem(traceFile + Constants.SUFFIX_TRACE_FILE);
+                } else {
+                    traceSystem = new TraceSystem(null);
+                }
             } else {
                 traceSystem = new TraceSystem(databaseName + Constants.SUFFIX_TRACE_FILE);
             }