Index: src/analyze.c
==================================================================
--- src/analyze.c
+++ src/analyze.c
@@ -1527,11 +1527,23 @@
     }
     aiRowEst = pIndex->aiRowEst;
 #endif
     pIndex->bUnordered = 0;
     decodeIntArray((char*)z, nCol, aiRowEst, pIndex->aiRowLogEst, pIndex);
-    if( pIndex->pPartIdxWhere==0 ) pTable->nRowLogEst = pIndex->aiRowLogEst[0];
+    if( pIndex->pPartIdxWhere==0 ){
+      int i, j;
+      /* TUNING: Any column that cannot narrow down the number of table rows
+      ** to less than 30 should not be considered as a column for use in
+      ** an automatic index */
+      for(i=0; i<nCol; i++){
+        assert( 49==sqlite3LogEst(30) );
+        if( aiRowEst[i+1]>49 && (j = pIndex->aiColumn[i])>=0 ){
+          pTable->aCol[j].colFlags |= COLFLAG_NOAUTO;
+        }
+      }
+      pTable->nRowLogEst = pIndex->aiRowLogEst[0];
+    }
   }else{
     Index fakeIdx;
     fakeIdx.szIdxRow = pTable->szTabRow;
 #ifdef SQLITE_ENABLE_COSTMULT
     fakeIdx.pTable = pTable;

Index: src/build.c
==================================================================
--- src/build.c
+++ src/build.c
@@ -3151,12 +3151,20 @@
     }else{
       j = pCExpr->iColumn;
       assert( j<=0x7fff );
       if( j<0 ){
         j = pTab->iPKey;
-      }else if( pTab->aCol[j].notNull==0 ){
-        pIndex->uniqNotNull = 0;
+      }else{
+        if( pTab->aCol[j].notNull==0 ){
+          pIndex->uniqNotNull = 0;
+        }
+        if( i==0 && pPIWhere==0 ){
+          /* Exclude the left-most column of every complete index from
+          ** consideration as an automatic index term.  Better to use the real
+          ** index */
+          pTab->aCol[j].colFlags |= COLFLAG_NOAUTO;
+        }
       }
       pIndex->aiColumn[i] = (i16)j;
     }
     zColl = 0;
     if( pListItem->pExpr->op==TK_COLLATE ){

Index: src/sqliteInt.h
==================================================================
--- src/sqliteInt.h
+++ src/sqliteInt.h
@@ -1538,10 +1538,11 @@
 
 /* Allowed values for Column.colFlags:
 */
 #define COLFLAG_PRIMKEY  0x0001    /* Column is part of the primary key */
 #define COLFLAG_HIDDEN   0x0002    /* A hidden column in a virtual table */
+#define COLFLAG_NOAUTO   0x0004    /* Not useful in an automatic index */
 
 /*
 ** A "Collating Sequence" is defined by an instance of the following
 ** structure. Conceptually, a collating sequence consists of a name and
 ** a comparison routine that defines the order of that sequence.

Index: src/where.c
==================================================================
--- src/where.c
+++ src/where.c
@@ -576,19 +576,23 @@
 ** index existed.
 */
 static int termCanDriveIndex(
   WhereTerm *pTerm,              /* WHERE clause term to check */
   struct SrcList_item *pSrc,     /* Table we are trying to access */
-  Bitmask notReady               /* Tables in outer loops of the join */
+  Bitmask notReady,              /* Tables in outer loops of the join */
+  int excludeNoauto              /* Answer FALSE if pTerm is COLFLAG_NOAUTO */
 ){
   char aff;
+  Column *pCol;
   if( pTerm->leftCursor!=pSrc->iCursor ) return 0;
   if( (pTerm->eOperator & (WO_EQ|WO_IS))==0 ) return 0;
   if( (pTerm->prereqRight & notReady)!=0 ) return 0;
   if( pTerm->u.leftColumn<0 ) return 0;
-  aff = pSrc->pTab->aCol[pTerm->u.leftColumn].affinity;
+  pCol = &pSrc->pTab->aCol[pTerm->u.leftColumn];
+  aff = pCol->affinity;
   if( !sqlite3IndexAffinityOk(pTerm->pExpr, aff) ) return 0;
+  if( excludeNoauto && (pCol->colFlags & COLFLAG_NOAUTO)!=0 ) return 0;
   testcase( pTerm->pExpr->op==TK_IS );
   return 1;
 }
 #endif
 
@@ -653,11 +657,11 @@
      && !ExprHasProperty(pExpr, EP_FromJoin)
      && sqlite3ExprIsTableConstant(pExpr, pSrc->iCursor) ){
       pPartial = sqlite3ExprAnd(pParse->db, pPartial,
                                 sqlite3ExprDup(pParse->db, pExpr, 0));
     }
-    if( termCanDriveIndex(pTerm, pSrc, notReady) ){
+    if( termCanDriveIndex(pTerm, pSrc, notReady, 0) ){
       int iCol = pTerm->u.leftColumn;
       Bitmask cMask = iCol>=BMS ? MASKBIT(BMS-1) : MASKBIT(iCol);
       testcase( iCol==BMS );
       testcase( iCol==BMS-1 );
       if( !sentWarning ){
@@ -706,11 +710,11 @@
   pIdx->zName = "auto-index";
   pIdx->pTable = pTable;
   n = 0;
   idxCols = 0;
   for(pTerm=pWC->a; pTerm<pWCEnd; pTerm++){
-    if( termCanDriveIndex(pTerm, pSrc, notReady) ){
+    if( termCanDriveIndex(pTerm, pSrc, notReady, 0) ){
       int iCol = pTerm->u.leftColumn;
       Bitmask cMask = iCol>=BMS ? MASKBIT(BMS-1) : MASKBIT(iCol);
       testcase( iCol==BMS-1 );
       testcase( iCol==BMS );
       if( (idxCols & cMask)==0 ){
@@ -2625,11 +2629,11 @@
     /* Generate auto-index WhereLoops */
     WhereTerm *pTerm;
     WhereTerm *pWCEnd = pWC->a + pWC->nTerm;
     for(pTerm=pWC->a; rc==SQLITE_OK && pTerm<pWCEnd; pTerm++){
       if( pTerm->prereqRight & pNew->maskSelf ) continue;
-      if( termCanDriveIndex(pTerm, pSrc, 0) ){
+      if( termCanDriveIndex(pTerm, pSrc, 0, 1) ){
         pNew->u.btree.nEq = 1;
         pNew->nSkip = 0;
         pNew->u.btree.pIndex = 0;
         pNew->nLTerm = 1;
         pNew->aLTerm[0] = pTerm;