Index: ext/fts3/fts3.c
==================================================================
--- ext/fts3/fts3.c
+++ ext/fts3/fts3.c
@@ -1469,10 +1469,23 @@
   sqlite3_vtab **ppVtab,          /* OUT: New sqlite3_vtab object */
   char **pzErr                    /* OUT: sqlite3_malloc'd error message */
 ){
   return fts3InitVtab(1, db, pAux, argc, argv, ppVtab, pzErr);
 }
+
+/*
+** Set the pIdxInfo->estimatedRows variable to nRow. Unless this
+** extension is currently being used by a version of SQLite too old to
+** support estimatedRows. In that case this function is a no-op.
+*/
+static void setEstimatedRows(sqlite3_index_info *pIdxInfo, i64 nRow){
+#if SQLITE_VERSION_NUMBER>=3008002
+  if( sqlite3_libversion_number()>=3008002 ){
+    pIdxInfo->estimatedRows = nRow;
+  }
+#endif
+}
 
 /* 
 ** Implementation of the xBestIndex method for FTS3 tables. There
 ** are three possible strategies, in order of preference:
 **
@@ -1497,11 +1510,24 @@
   pInfo->idxNum = FTS3_FULLSCAN_SEARCH;
   pInfo->estimatedCost = 5000000;
   for(i=0; i<pInfo->nConstraint; i++){
     int bDocid;                 /* True if this constraint is on docid */
     struct sqlite3_index_constraint *pCons = &pInfo->aConstraint[i];
-    if( pCons->usable==0 ) continue;
+    if( pCons->usable==0 ){
+      if( pCons->op==SQLITE_INDEX_CONSTRAINT_MATCH ){
+        /* There exists an unusable MATCH constraint. This means that if
+        ** the planner does elect to use the results of this call as part
+        ** of the overall query plan the user will see an "unable to use
+        ** function MATCH in the requested context" error. To discourage
+        ** this, return a very high cost here.  */
+        pInfo->idxNum = FTS3_FULLSCAN_SEARCH;
+        pInfo->estimatedCost = 1e50;
+        setEstimatedRows(pInfo, ((sqlite3_int64)1) << 50);
+        return SQLITE_OK;
+      }
+      continue;
+    }
 
     bDocid = (pCons->iColumn<0 || pCons->iColumn==p->nColumn+1);
 
     /* A direct lookup on the rowid or docid column. Assign a cost of 1.0. */
     if( iCons<0 && pCons->op==SQLITE_INDEX_CONSTRAINT_EQ && bDocid ){

ADDED   test/fts3join.test
Index: test/fts3join.test
==================================================================
--- /dev/null
+++ test/fts3join.test
@@ -0,0 +1,66 @@
+# 2014 January 4
+#
+# The author disclaims copyright to this source code.  In place of
+# a legal notice, here is a blessing:
+#
+#    May you do good and not evil.
+#    May you find forgiveness for yourself and forgive others.
+#    May you share freely, never taking more than you give.
+#
+#*************************************************************************
+# This file implements regression tests for SQLite library.  The
+# focus of this script is testing the FTS3 module.
+#
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+set ::testprefix fts3join
+
+# If SQLITE_ENABLE_FTS3 is defined, omit this file.
+ifcapable !fts3 {
+  finish_test
+  return
+}
+
+do_execsql_test 1.0 {
+  CREATE VIRTUAL TABLE ft1 USING fts4(x);
+  INSERT INTO ft1 VALUES('aaa aaa');
+  INSERT INTO ft1 VALUES('aaa bbb');
+  INSERT INTO ft1 VALUES('bbb aaa');
+  INSERT INTO ft1 VALUES('bbb bbb');
+
+  CREATE TABLE t1(id, y);
+  INSERT INTO t1 VALUES(1, 'aaa');
+  INSERT INTO t1 VALUES(2, 'bbb');
+}
+
+do_execsql_test 1.1 {
+  SELECT docid FROM ft1, t1 WHERE ft1 MATCH y AND id=1;
+} {1 2 3}
+
+do_execsql_test 1.2 {
+  SELECT docid FROM ft1, t1 WHERE ft1 MATCH y AND id=1 ORDER BY docid;
+} {1 2 3}
+
+do_execsql_test 2.0 {
+  CREATE VIRTUAL TABLE ft2 USING fts4(x);
+  CREATE VIRTUAL TABLE ft3 USING fts4(y);
+
+  INSERT INTO ft2 VALUES('abc');
+  INSERT INTO ft2 VALUES('def');
+  INSERT INTO ft3 VALUES('ghi');
+  INSERT INTO ft3 VALUES('abc');
+}
+
+do_execsql_test 2.1 { SELECT * FROM ft2, ft3 WHERE x MATCH y; } {abc abc}
+do_execsql_test 2.2 { SELECT * FROM ft2, ft3 WHERE y MATCH x; } {abc abc}
+do_execsql_test 2.3 { SELECT * FROM ft3, ft2 WHERE x MATCH y; } {abc abc}
+do_execsql_test 2.4 { SELECT * FROM ft3, ft2 WHERE y MATCH x; } {abc abc}
+
+do_catchsql_test 2.5 { 
+  SELECT * FROM ft3, ft2 WHERE y MATCH x AND x MATCH y; 
+} {1 {unable to use function MATCH in the requested context}}
+
+finish_test
+
+