--- a/src/org/tmatesoft/hg/internal/FNCacheFile.java	Mon Feb 25 18:41:44 2013 +0100
+++ b/src/org/tmatesoft/hg/internal/FNCacheFile.java	Mon Feb 25 19:48:20 2013 +0100
@@ -21,27 +21,35 @@
 import java.io.IOException;
 import java.nio.charset.Charset;
 import java.util.ArrayList;
+import java.util.List;
 
 import org.tmatesoft.hg.util.Path;
 
 /**
+ * Append-only fncache support
+ * 
  * <blockquote>
  * The fncache file contains the paths of all filelog files in the store as encoded by mercurial.filelog.encodedir. The paths are separated by '\n' (LF).
  * </blockquote>
  * @see http://mercurial.selenic.com/wiki/fncacheRepoFormat
+ * 
+ * 
  * @author Artem Tikhomirov
  * @author TMate Software Ltd.
  */
 public class FNCacheFile {
 	
 	private final Internals repo;
-	private final ArrayList<Path> files;
+//	private final List<Path> files;
+	private List<Path> added;
 
 	public FNCacheFile(Internals internalRepo) {
 		repo = internalRepo;
-		files = new ArrayList<Path>();
+//		files = new ArrayList<Path>();
 	}
 
+	/*
+	 * For append-only option, we don't care reading the original content
 	public void read(Path.Source pathFactory) throws IOException {
 		File f = fncacheFile();
 		files.clear();
@@ -52,20 +60,22 @@
 		// names in fncache are in local encoding, shall translate to unicode
 		new LineReader(f, repo.getSessionContext().getLog(), repo.getFilenameEncoding()).read(new LineReader.SimpleLineCollector(), entries);
 		for (String e : entries) {
+			// FIXME plain wrong, need either to decode paths and strip off .i/.d or (if keep names as is) change write()
 			files.add(pathFactory.path(e));
 		}
 	}
+	*/
 	
 	public void write() throws IOException {
-		if (files.isEmpty()) {
+		if (added == null || added.isEmpty()) {
 			return;
 		}
 		File f = fncacheFile();
 		f.getParentFile().mkdirs();
 		final Charset filenameEncoding = repo.getFilenameEncoding();
-		FileOutputStream fncacheFile = new FileOutputStream(f);
-		for (Path p : files) {
-			String s = "data/" + p.toString() + ".i"; // TODO post-1.0 this is plain wrong. (a) likely need .d files, too; (b) what about dh/ location? 
+		FileOutputStream fncacheFile = new FileOutputStream(f, true);
+		for (Path p : added) {
+			String s = "data/" + p.toString() + ".i"; // TODO post-1.0 this is plain wrong. (a) need .d files, too; (b) what about dh/ location? 
 			fncacheFile.write(s.getBytes(filenameEncoding));
 			fncacheFile.write(0x0A); // http://mercurial.selenic.com/wiki/fncacheRepoFormat
 		}
@@ -73,7 +83,10 @@
 	}
 
 	public void add(Path p) {
-		files.add(p);
+		if (added == null) {
+			added = new ArrayList<Path>();
+		}
+		added.add(p);
 	}
 
 	private File fncacheFile() {