Index: src/vdbe.c
==================================================================
--- src/vdbe.c
+++ src/vdbe.c
@@ -2163,22 +2163,20 @@
 
 /* Opcode: MakeIdxKey P1 P2 P3 P4 P5
 **
 ** P1 is an open cursor. P2 is the first register in a contiguous array
 ** of N registers containing values to encode into a database key. Normally,
-** N is equal to the number of columns indexed by P1, plus the number of 
-** trailing primary key columns (if any). 
-**
-** Or, if P4 is a non-zero integer, then it contains the value for N.
+** N is taken from the KeyInfo object of P1.  However, of P4 is a positive
+** integer, P4 is used for N instead.
 **
 ** This instruction encodes the N values into a database key and writes
 ** the result to register P3. No affinity transformations are applied to 
 ** the input values before they are encoded. 
 **
 ** If the OPFLAG_SEQCOUNT bit of P5 is set, then a sequence number 
 ** (unique within the cursor) is appended to the record. The sole purpose
-** of this is to ensure that the key blob is unique within the cursors table.
+** of this is to ensure that the key blob is unique within the cursor table.
 **
 ** If the OPFLAG_PARTIALKEY bit of P5 is set, that means the value supplied
 ** for N is not the true number of values in the key, only the number that
 ** need to be encoded for this operation.  This effects the encoding of
 ** final BLOBs.
@@ -2198,13 +2196,15 @@
   pKeyInfo = pC->pKeyInfo;
   pData0 = &aMem[pOp->p2];
   pOut = &aMem[pOp->p3];
   aRec = 0;
 
-  /* If pOp->p5 is non-zero, encode the sequence number blob to append to
-  ** the end of the key. Variable nSeq is set to the number of bytes in
-  ** the encoded key.
+  /* If P4 contains OPFLAG_SEQCOUNT, encode the sequence number blob to be
+  ** appended to the end of the key.  Variable nSeq is set to the number
+  ** of bytes in the encoded key.  A non-standard encoding is used (not
+  ** the usual varint encoding) so that the OP_GrpCompare opcode can easily
+  ** back up over the sequence count to find the true end of the key.
   */
   nSeq = 0;
   if( pOp->p5 & OPFLAG_SEQCOUNT ){
     iSeq = pC->seqCount++;
     do {
@@ -2215,16 +2215,18 @@
     aSeq[sizeof(aSeq)-nSeq] |= 0x80;
   }
 
   memAboutToChange(p, pOut);
 
-  nField = pOp->p4.i;
-  if( nField==0 ) nField = pKeyInfo->nField;
+//  nField = pOp->p4.i;
+//  if( nField==0 ) nField = pKeyInfo->nField;
 
   if( pOp->p4type==P4_INT32 && pOp->p4.i ){
     nField = pOp->p4.i;
     assert( nField<=pKeyInfo->nField );
+  }else{
+    nField = pKeyInfo->nField;
   }
   rc = sqlite4VdbeEncodeKey(
     db, pData0, nField, pKeyInfo->nField,
     pC->iRoot, pKeyInfo, &aRec, &nRec, nSeq
   );