diff --git a/manifest b/manifest
index 0da10ee6c4..953aa940c7 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Allow\sconstraint\snames\son\sDEFAULT\svalues\sin\sa\stable\sdefinition.\nTicket\s#2109.\s(CVS\s3535)
-D 2006-12-20T02:15:00
+C The\squery\soptimizer\sdoes\sa\sbetter\sjob\sof\soptimizing\sout\sORDER\sBY\sclauses\nthat\scontain\sthe\srowid\sor\swhich\suse\sindices\sthat\scontain\sthe\srowid.\nTicket\s#2116.\s(CVS\s3536)
+D 2006-12-20T03:24:19
 F Makefile.in 8e14898d41a53033ecb687d93c9cd5d109fb9ae3
 F Makefile.linux-gcc 2d8574d1ba75f129aba2019f0b959db380a90935
 F README 9c4e2d6706bdcc3efdd773ce752a8cdab4f90028
@@ -129,7 +129,7 @@ F src/vdbeaux.c 05cc6f0f82b86dfb4c356e06ab07ec8cc83a2eda
 F src/vdbefifo.c 9efb94c8c3f4c979ebd0028219483f88e57584f5
 F src/vdbemem.c 26623176bf1c616aa478da958fac49502491a921
 F src/vtab.c aa30e940058ea56a1b7a9a7019ec21d307316fb4
-F src/where.c b34cc2c7f753cdf76aa37a71e579c2e266e50958
+F src/where.c f55d4459a122457a135cf9ec859bf28777d9156f
 F tclinstaller.tcl 046e3624671962dc50f0481d7c25b38ef803eb42
 F test/aggerror.test a867e273ef9e3d7919f03ef4f0e8c0d2767944f2
 F test/all.test b62fcd122052efaff1b0979aefa2dd65cfc8ee52
@@ -348,7 +348,7 @@ F test/vtab6.test ec0036f29f8a803da9935206f2d9d1b6a8026392
 F test/vtab7.test 5f9ef9fb84733e928d5d0267c821072561b198d5
 F test/vtab9.test 87afba55339b0c255e9697fbfb5bfb6120505d9d
 F test/vtab_err.test c07f7665dd90bc757f80f05e7951d826eda9bc48
-F test/where.test ee7c9a6659b07e1ee61177f6e7ff71565ee2c9df
+F test/where.test 8dcc1b1a6f17b6bad2dc6a9917eafe62d4ea57eb
 F test/where2.test 61d5b20d9bedc8788a773bbdc5b2ef887725928e
 F test/where3.test 0a30fe9808b0fa01c46d0fcf4fac0bf6cf75bb30
 F tool/diffdb.c 7524b1b5df217c20cd0431f6789851a4e0cb191b
@@ -423,7 +423,7 @@ F www/tclsqlite.tcl bb0d1357328a42b1993d78573e587c6dcbc964b9
 F www/vdbe.tcl 87a31ace769f20d3627a64fa1fade7fed47b90d0
 F www/version3.tcl 890248cf7b70e60c383b0e84d77d5132b3ead42b
 F www/whentouse.tcl 97e2b5cd296f7d8057e11f44427dea8a4c2db513
-P c3d118b40811b201e4a98b62549c5439d7d5098d
-R ee31e902c9098dae721605bcf38ca561
+P 893d58c23da2a9b900a13eaa5202d94429862136
+R b71e90ccc82c8a1640aa72f2c870612e
 U drh
-Z 6de8d7d606a906d10c3edc457d084a8d
+Z 9fec3d60f3cf9eea1be494a067e0f511
diff --git a/manifest.uuid b/manifest.uuid
index 2ad57094a0..89fb96bd75 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-893d58c23da2a9b900a13eaa5202d94429862136
\ No newline at end of file
+f245f5c2c2d337fe6458824beb7f9e721837765f
\ No newline at end of file
diff --git a/src/where.c b/src/where.c
index 1d640cb26e..a0d2f81096 100644
--- a/src/where.c
+++ b/src/where.c
@@ -16,7 +16,7 @@
 ** so is applicable.  Because this module is responsible for selecting
 ** indices, you might also think of this module as the "query optimizer".
 **
-** $Id: where.c,v 1.233 2006/12/16 16:25:16 drh Exp $
+** $Id: where.c,v 1.234 2006/12/20 03:24:19 drh Exp $
 */
 #include "sqliteInt.h"
 
@@ -868,11 +868,19 @@ static int isSortingIndex(
 
   /* Match terms of the ORDER BY clause against columns of
   ** the index.
+  **
+  ** Note that indices have pIdx->nColumn regular columns plus
+  ** one additional column containing the rowid.  The rowid column
+  ** of the index is also allowed to match against the ORDER BY
+  ** clause.
   */
-  for(i=j=0, pTerm=pOrderBy->a; j<nTerm && i<pIdx->nColumn; i++){
+  for(i=j=0, pTerm=pOrderBy->a; j<nTerm && i<=pIdx->nColumn; i++){
     Expr *pExpr;       /* The expression of the ORDER BY pTerm */
     CollSeq *pColl;    /* The collating sequence of pExpr */
     int termSortOrder; /* Sort order for this term */
+    int iColumn;       /* The i-th column of the index.  -1 for rowid */
+    int iSortOrder;    /* 1 for DESC, 0 for ASC on the i-th index term */
+    const char *zColl; /* Name of the collating sequence for i-th index term */
 
     pExpr = pTerm->pExpr;
     if( pExpr->op!=TK_COLUMN || pExpr->iTable!=base ){
@@ -881,9 +889,22 @@ static int isSortingIndex(
       return 0;
     }
     pColl = sqlite3ExprCollSeq(pParse, pExpr);
-    if( !pColl ) pColl = db->pDfltColl;
-    if( pExpr->iColumn!=pIdx->aiColumn[i] || 
-        sqlite3StrICmp(pColl->zName, pIdx->azColl[i]) ){
+    if( !pColl ){
+      pColl = db->pDfltColl;
+    }
+    if( i<pIdx->nColumn ){
+      iColumn = pIdx->aiColumn[i];
+      if( iColumn==pIdx->pTable->iPKey ){
+        iColumn = -1;
+      }
+      iSortOrder = pIdx->aSortOrder[i];
+      zColl = pIdx->azColl[i];
+    }else{
+      iColumn = -1;
+      iSortOrder = 0;
+      zColl = pColl->zName;
+    }
+    if( pExpr->iColumn!=iColumn || sqlite3StrICmp(pColl->zName, zColl) ){
       /* Term j of the ORDER BY clause does not match column i of the index */
       if( i<nEqCol ){
         /* If an index column that is constrained by == fails to match an
@@ -899,8 +920,8 @@ static int isSortingIndex(
     }
     assert( pIdx->aSortOrder!=0 );
     assert( pTerm->sortOrder==0 || pTerm->sortOrder==1 );
-    assert( pIdx->aSortOrder[i]==0 || pIdx->aSortOrder[i]==1 );
-    termSortOrder = pIdx->aSortOrder[i] ^ pTerm->sortOrder;
+    assert( iSortOrder==0 || iSortOrder==1 );
+    termSortOrder = iSortOrder ^ pTerm->sortOrder;
     if( i>nEqCol ){
       if( termSortOrder!=sortOrder ){
         /* Indices can only be used if all ORDER BY terms past the
@@ -912,13 +933,25 @@ static int isSortingIndex(
     }
     j++;
     pTerm++;
+    if( iColumn<0 ){
+      /* If the indexed column is the primary key and everything matches
+      ** so far, then we are assured that the index can be used to sort
+      ** because the primary key is unique and so none of the other columns
+      ** will make any difference
+      */
+      j = nTerm;
+    }
   }
 
-  /* The index can be used for sorting if all terms of the ORDER BY clause
-  ** are covered.
-  */
+  *pbRev = sortOrder!=0;
   if( j>=nTerm ){
-    *pbRev = sortOrder!=0;
+    /* All terms of the ORDER BY clause are covered by this index so
+    ** this index can be used for sorting. */
+    return 1;
+  }
+  if( j==pIdx->nColumn && pIdx->onError!=OE_None ){
+    /* All terms of this index match some prefix of the ORDER BY clause
+    ** and this index is UNIQUE, so this index can be used for sorting. */
     return 1;
   }
   return 0;
@@ -939,8 +972,7 @@ static int sortableByRowid(
   assert( pOrderBy!=0 );
   assert( pOrderBy->nExpr>0 );
   p = pOrderBy->a[0].pExpr;
-  if( pOrderBy->nExpr==1 && p->op==TK_COLUMN && p->iTable==base
-          && p->iColumn==-1 ){
+  if( p->op==TK_COLUMN && p->iTable==base && p->iColumn==-1 ){
     *pbRev = pOrderBy->a[0].sortOrder;
     return 1;
   }
diff --git a/test/where.test b/test/where.test
index 83bcd0b8d6..8eeb3f81e6 100644
--- a/test/where.test
+++ b/test/where.test
@@ -11,7 +11,7 @@
 # This file implements regression tests for SQLite library.  The
 # focus of this file is testing the use of indices in WHERE clases.
 #
-# $Id: where.test,v 1.38 2005/11/14 22:29:06 drh Exp $
+# $Id: where.test,v 1.39 2006/12/20 03:24:19 drh Exp $
 
 set testdir [file dirname $argv0]
 source $testdir/tester.tcl
@@ -589,22 +589,22 @@ do_test where-6.21 {
   cksort {
     SELECT y FROM t1 ORDER BY rowid, y LIMIT 3;
   }
-} {4 9 16 sort}
+} {4 9 16 nosort}
 do_test where-6.22 {
   cksort {
     SELECT y FROM t1 ORDER BY rowid, y DESC LIMIT 3;
   }
-} {4 9 16 sort}
+} {4 9 16 nosort}
 do_test where-6.23 {
   cksort {
     SELECT y FROM t1 WHERE y>4 ORDER BY rowid, w, x LIMIT 3;
   }
-} {9 16 25 sort}
+} {9 16 25 nosort}
 do_test where-6.24 {
   cksort {
     SELECT y FROM t1 WHERE y>=9 ORDER BY rowid, x DESC, w LIMIT 3;
   }
-} {9 16 25 sort}
+} {9 16 25 nosort}
 do_test where-6.25 {
   cksort {
     SELECT y FROM t1 WHERE y>4 AND y<25 ORDER BY rowid;
@@ -619,7 +619,7 @@ do_test where-6.27 {
   cksort {
     SELECT y FROM t1 WHERE y<=25 ORDER BY _rowid_, w+y;
   }
-} {4 9 16 25 sort}
+} {4 9 16 25 nosort}
 
 
 # Tests for reverse-order sorting.
@@ -793,7 +793,7 @@ do_test where-7.34 {
   cksort {
     SELECT y FROM t1 WHERE y<25 AND y>4 ORDER BY rowid DESC, y DESC
   }
-} {16 9 sort}
+} {16 9 nosort}
 do_test where-7.35 {
   cksort {
     SELECT y FROM t1 WHERE y<25 AND y>=4 ORDER BY rowid DESC
@@ -874,7 +874,6 @@ do_test where-10.4 {
 # that array.
 #
 do_test where-11.1 {
-btree_breakpoint
   execsql {
    CREATE TABLE t99(Dte INT, X INT);
    DELETE FROM t99 WHERE (Dte = 2451337) OR (Dte = 2451339) OR
@@ -902,6 +901,143 @@ btree_breakpoint
   }
 } {}
 
+# Ticket #2116:  Make sure sorting by index works well with nn INTEGER PRIMARY
+# KEY.
+#
+do_test where-12.1 {
+  execsql {
+    CREATE TABLE t6(a INTEGER PRIMARY KEY, b TEXT);
+    INSERT INTO t6 VALUES(1,'one');
+    INSERT INTO t6 VALUES(4,'four');
+    CREATE INDEX t6i1 ON t6(b);
+  }
+  cksort {
+    SELECT * FROM t6 ORDER BY b;
+  }
+} {4 four 1 one nosort}
+do_test where-12.2 {
+  cksort {
+    SELECT * FROM t6 ORDER BY b, a;
+  }
+} {4 four 1 one nosort}
+do_test where-12.3 {
+  cksort {
+    SELECT * FROM t6 ORDER BY a;
+  }
+} {1 one 4 four nosort}
+do_test where-12.4 {
+  cksort {
+    SELECT * FROM t6 ORDER BY a, b;
+  }
+} {1 one 4 four nosort}
+do_test where-12.5 {
+  cksort {
+    SELECT * FROM t6 ORDER BY b DESC;
+  }
+} {1 one 4 four nosort}
+do_test where-12.6 {
+  cksort {
+    SELECT * FROM t6 ORDER BY b DESC, a DESC;
+  }
+} {1 one 4 four nosort}
+do_test where-12.7 {
+  cksort {
+    SELECT * FROM t6 ORDER BY b DESC, a ASC;
+  }
+} {1 one 4 four sort}
+do_test where-12.8 {
+  cksort {
+    SELECT * FROM t6 ORDER BY b ASC, a DESC;
+  }
+} {4 four 1 one sort}
+do_test where-12.9 {
+  cksort {
+    SELECT * FROM t6 ORDER BY a DESC;
+  }
+} {4 four 1 one nosort}
+do_test where-12.10 {
+  cksort {
+    SELECT * FROM t6 ORDER BY a DESC, b DESC;
+  }
+} {4 four 1 one nosort}
+do_test where-12.11 {
+  cksort {
+    SELECT * FROM t6 ORDER BY a DESC, b ASC;
+  }
+} {4 four 1 one nosort}
+do_test where-12.12 {
+  cksort {
+    SELECT * FROM t6 ORDER BY a ASC, b DESC;
+  }
+} {1 one 4 four nosort}
+do_test where-13.1 {
+  execsql {
+    CREATE TABLE t7(a INTEGER PRIMARY KEY, b TEXT);
+    INSERT INTO t7 VALUES(1,'one');
+    INSERT INTO t7 VALUES(4,'four');
+    CREATE INDEX t7i1 ON t7(b);
+  }
+  cksort {
+    SELECT * FROM t7 ORDER BY b;
+  }
+} {4 four 1 one nosort}
+do_test where-13.2 {
+  cksort {
+    SELECT * FROM t7 ORDER BY b, a;
+  }
+} {4 four 1 one nosort}
+do_test where-13.3 {
+  cksort {
+    SELECT * FROM t7 ORDER BY a;
+  }
+} {1 one 4 four nosort}
+do_test where-13.4 {
+  cksort {
+    SELECT * FROM t7 ORDER BY a, b;
+  }
+} {1 one 4 four nosort}
+do_test where-13.5 {
+  cksort {
+    SELECT * FROM t7 ORDER BY b DESC;
+  }
+} {1 one 4 four nosort}
+do_test where-13.6 {
+  cksort {
+    SELECT * FROM t7 ORDER BY b DESC, a DESC;
+  }
+} {1 one 4 four nosort}
+do_test where-13.7 {
+  cksort {
+    SELECT * FROM t7 ORDER BY b DESC, a ASC;
+  }
+} {1 one 4 four sort}
+do_test where-13.8 {
+  cksort {
+    SELECT * FROM t7 ORDER BY b ASC, a DESC;
+  }
+} {4 four 1 one sort}
+do_test where-13.9 {
+  cksort {
+    SELECT * FROM t7 ORDER BY a DESC;
+  }
+} {4 four 1 one nosort}
+do_test where-13.10 {
+  cksort {
+    SELECT * FROM t7 ORDER BY a DESC, b DESC;
+  }
+} {4 four 1 one nosort}
+do_test where-13.11 {
+  cksort {
+    SELECT * FROM t7 ORDER BY a DESC, b ASC;
+  }
+} {4 four 1 one nosort}
+do_test where-13.12 {
+  cksort {
+    SELECT * FROM t7 ORDER BY a ASC, b DESC;
+  }
+} {1 one 4 four nosort}
+
+
 
 integrity_check {where-99.0}