ORC-229. Add an UNSTABLE-PRE-2.0 file format version.

Fixes #153

Signed-off-by: Owen O'Malley <omalley@apache.org>

java/core/src/java/org/apache/orc/OrcFile.java

@@ -62,6 +62,20 @@ public class OrcFile {
   public enum Version {
     V_0_11("0.11", 0, 11),
     V_0_12("0.12", 0, 12),
+
+    /**
+     * Do not use this format except for testing. It will not be compatible
+     * with other versions of the software. While we iterate on the ORC 2.0
+     * format, we will make incompatible format changes under this version
+     * without providing any forward or backward compatibility.
+     *
+     * When 2.0 is released, this version identifier will be completely removed.
+     */
+    UNSTABLE_PRE_2_0("UNSTABLE-PRE-2.0", 1, 9999),
+
+    /**
+     * The generic identifier for all unknown versions.
+     */
     FUTURE("future", Integer.MAX_VALUE, Integer.MAX_VALUE);
 
     public static final Version CURRENT = V_0_12;

java/core/src/java/org/apache/orc/impl/WriterImpl.java

@@ -149,6 +149,13 @@ public Writer getWriter() {
       this.bufferSize = getEstimatedBufferSize(adjustedStripeSize,
           numColumns, opts.getBufferSize());
     }
+    if (version == OrcFile.Version.FUTURE) {
+      throw new IllegalArgumentException("Can not write in a unknown version.");
+    } else if (version == OrcFile.Version.UNSTABLE_PRE_2_0) {
+      LOG.warn("ORC files written in " + version.getName() + " will not be" +
+          " readable by other versions of the software. It is only for" +
+          " developer testing.");
+    }
     if (version == OrcFile.Version.V_0_11) {
       /* do not write bloom filters for ORC v11 */
       this.bloomFilterColumns = new boolean[schema.getMaximumId() + 1];