Index: src/where.c
==================================================================
--- src/where.c
+++ src/where.c
@@ -4010,31 +4010,35 @@
     sqlite3DbFree(db, pWInfo);
   }
 }
 
 /*
-** Return TRUE if both of the following are true:
+** Return TRUE if all of the following are true:
 **
 **   (1)  X has the same or lower cost that Y
 **   (2)  X is a proper subset of Y
+**   (3)  X skips at least as many columns as Y
 **
 ** By "proper subset" we mean that X uses fewer WHERE clause terms
 ** than Y and that every WHERE clause term used by X is also used
 ** by Y.
 **
 ** If X is a proper subset of Y then Y is a better choice and ought
 ** to have a lower cost.  This routine returns TRUE when that cost 
-** relationship is inverted and needs to be adjusted.
+** relationship is inverted and needs to be adjusted.  The third rule
+** was added because if X uses skip-scan less than Y it still might
+** deserve a lower cost even if it is a proper subset of Y.
 */
 static int whereLoopCheaperProperSubset(
   const WhereLoop *pX,       /* First WhereLoop to compare */
   const WhereLoop *pY        /* Compare against this WhereLoop */
 ){
   int i, j;
   if( pX->nLTerm-pX->nSkip >= pY->nLTerm-pY->nSkip ){
     return 0; /* X is not a subset of Y */
   }
+  if( pY->nSkip > pX->nSkip ) return 0;
   if( pX->rRun >= pY->rRun ){
     if( pX->rRun > pY->rRun ) return 0;    /* X costs more than Y */
     if( pX->nOut > pY->nOut ) return 0;    /* X costs more than Y */
   }
   for(i=pX->nLTerm-1; i>=0; i--){
@@ -4066,13 +4070,11 @@
   for(; p; p=p->pNextLoop){
     if( p->iTab!=pTemplate->iTab ) continue;
     if( (p->wsFlags & WHERE_INDEXED)==0 ) continue;
     if( whereLoopCheaperProperSubset(p, pTemplate) ){
       /* Adjust pTemplate cost downward so that it is cheaper than its 
-      ** subset p.  Except, do not adjust the cost estimate downward for
-      ** a loop that skips more columns. */
-      if( pTemplate->nSkip>p->nSkip ) continue;
+      ** subset p. */
       WHERETRACE(0x80,("subset cost adjustment %d,%d to %d,%d\n",
                        pTemplate->rRun, pTemplate->nOut, p->rRun, p->nOut-1));
       pTemplate->rRun = p->rRun;
       pTemplate->nOut = p->nOut - 1;
     }else if( whereLoopCheaperProperSubset(pTemplate, p) ){