Index: src/build.c
==================================================================
--- src/build.c
+++ src/build.c
@@ -3925,14 +3925,17 @@
     assert( p->nSrc>0 );
     pItem = &p->a[p->nSrc-1];
     assert( pItem->fg.notIndexed==0 );
     assert( pItem->fg.isIndexedBy==0 );
     assert( pItem->fg.isTabFunc==0 );
-    if( pIndexedBy->n==1 && !pIndexedBy->z ){
-      /* A "NOT INDEXED" clause was supplied. See parse.y 
-      ** construct "indexed_opt" for details. */
-      pItem->fg.notIndexed = 1;
+    if( pIndexedBy->n>=1 && !pIndexedBy->z ){
+      if( pIndexedBy->n==1 ){
+        pItem->fg.notIndexed = 1;
+      }else{
+        assert( pIndexedBy->n==2 );
+        pItem->fg.useAutoIdx = 1;
+      }
     }else{
       pItem->u1.zIndexedBy = sqlite3NameFromToken(pParse->db, pIndexedBy);
       pItem->fg.isIndexedBy = 1;
     }
   }

Index: src/parse.y
==================================================================
--- src/parse.y
+++ src/parse.y
@@ -650,15 +650,16 @@
   A = sqlite3SrcListAppendFromTerm(pParse,A,&Y,&D,&Z,0,N,U);
   sqlite3SrcListFuncArgs(pParse, A, E);
 }
 %ifndef SQLITE_OMIT_SUBQUERY
   seltablist(A) ::= stl_prefix(A) LP select(S) RP
-                    as(Z) on_opt(N) using_opt(U). {
+                    as(Z) indexed_opt(I) on_opt(N) using_opt(U). {
     A = sqlite3SrcListAppendFromTerm(pParse,A,0,0,&Z,S,N,U);
+    sqlite3SrcListIndexedBy(pParse, A, &I);
   }
   seltablist(A) ::= stl_prefix(A) LP seltablist(F) RP
-                    as(Z) on_opt(N) using_opt(U). {
+                    as(Z) indexed_opt(I) on_opt(N) using_opt(U). {
     if( A==0 && Z.n==0 && N==0 && U==0 ){
       A = F;
     }else if( F->nSrc==1 ){
       A = sqlite3SrcListAppendFromTerm(pParse,A,0,0,&Z,0,N,U);
       if( A ){
@@ -675,10 +676,11 @@
       Select *pSubquery;
       sqlite3SrcListShiftJoinType(F);
       pSubquery = sqlite3SelectNew(pParse,0,F,0,0,0,0,SF_NestedFrom,0);
       A = sqlite3SrcListAppendFromTerm(pParse,A,0,0,&Z,pSubquery,N,U);
     }
+    sqlite3SrcListIndexedBy(pParse, A, &I);
   }
 %endif  SQLITE_OMIT_SUBQUERY
 
 %type dbnm {Token}
 dbnm(A) ::= .          {A.z=0; A.n=0;}
@@ -749,10 +751,11 @@
 //
 %type indexed_opt {Token}
 indexed_opt(A) ::= .                 {A.z=0; A.n=0;}
 indexed_opt(A) ::= INDEXED BY nm(X). {A = X;}
 indexed_opt(A) ::= NOT INDEXED.      {A.z=0; A.n=1;}
+indexed_opt(A) ::= INDEXED.          {A.z=0; A.n=2;}
 
 %type using_opt {IdList*}
 %destructor using_opt {sqlite3IdListDelete(pParse->db, $$);}
 using_opt(U) ::= USING LP idlist(L) RP.  {U = L;}
 using_opt(U) ::= .                        {U = 0;}

Index: src/sqliteInt.h
==================================================================
--- src/sqliteInt.h
+++ src/sqliteInt.h
@@ -2606,10 +2606,11 @@
       unsigned isIndexedBy :1;   /* True if there is an INDEXED BY clause */
       unsigned isTabFunc :1;     /* True if table-valued-function syntax */
       unsigned isCorrelated :1;  /* True if sub-query is correlated */
       unsigned viaCoroutine :1;  /* Implemented as a co-routine */
       unsigned isRecursive :1;   /* True for recursive reference in WITH */
+      unsigned useAutoIdx  :1;   /* Use an automatic index if possible */
     } fg;
     int iCursor;      /* The VDBE cursor number used to access this table */
     Expr *pOn;        /* The ON clause of a join */
     IdList *pUsing;   /* The USING clause of a join */
     Bitmask colUsed;  /* Bit N (1<<N) set if column N of pTab is used */

Index: src/where.c
==================================================================
--- src/where.c
+++ src/where.c
@@ -2870,11 +2870,11 @@
         pNew->rSetup = rLogSize + rSize + 4;
         if( pTab->pSelect==0 && (pTab->tabFlags & TF_Ephemeral)==0 ){
           pNew->rSetup += 24;
         }
         ApplyCostMultiplier(pNew->rSetup, pTab->costMult);
-        if( pNew->rSetup<0 ) pNew->rSetup = 0;
+        if( pNew->rSetup<0 || pSrc->fg.useAutoIdx ) pNew->rSetup = 0;
         /* TUNING: Each index lookup yields 20 rows in the table.  This
         ** is more than the usual guess of 10 rows, since we have no way
         ** of knowing how selective the index will ultimately be.  It would
         ** not be unreasonable to make this value much larger. */
         pNew->nOut = 43;  assert( 43==sqlite3LogEst(20) );
@@ -4003,13 +4003,16 @@
         Bitmask maskNew;                  /* Mask of src visited by (..) */
         Bitmask revMask = 0;              /* Mask of rev-order loops for (..) */
 
         if( (pWLoop->prereq & ~pFrom->maskLoop)!=0 ) continue;
         if( (pWLoop->maskSelf & pFrom->maskLoop)!=0 ) continue;
-        if( (pWLoop->wsFlags & WHERE_AUTO_INDEX)!=0 && pFrom->nRow<10 ){
+        if( (pWLoop->wsFlags & WHERE_AUTO_INDEX)!=0
+         && (pWInfo->wctrlFlags & WHERE_USE_LIMIT)!=0
+         && pWInfo->iLimit<10
+        ){
           /* Do not use an automatic index if the this loop is expected
-          ** to run less than 2 times. */
+          ** to run less than twice due to a LIMIT clause. */
           assert( 10==sqlite3LogEst(2) );
           continue;
         }
         /* At this point, pWLoop is a candidate to be the next loop. 
         ** Compute its cost */