Index: src/analyze.c
==================================================================
--- src/analyze.c
+++ src/analyze.c
@@ -1682,13 +1682,11 @@
     zIndex = (char *)sqlite3_column_text(pStmt, 0);
     if( zIndex==0 ) continue;
     nSample = sqlite3_column_int(pStmt, 1);
     pIdx = findIndexOrPrimaryKey(db, zIndex, zDb);
     assert( pIdx==0 || pIdx->nSample==0 );
-    /* Index.nSample is non-zero at this point if data has already been
-    ** loaded from the stat4 table. */
-    if( pIdx==0 || pIdx->nSample ) continue;
+    if( pIdx==0 ) continue;
     assert( !HasRowid(pIdx->pTable) || pIdx->nColumn==pIdx->nKeyCol+1 );
     if( !HasRowid(pIdx->pTable) && IsPrimaryKeyIndex(pIdx) ){
       nIdxCol = pIdx->nKeyCol;
     }else{
       nIdxCol = pIdx->nColumn;

Index: src/sqliteInt.h
==================================================================
--- src/sqliteInt.h
+++ src/sqliteInt.h
@@ -1571,12 +1571,12 @@
 #define SQLITE_OrderByIdxJoin 0x0040   /* ORDER BY of joins via index */
 #define SQLITE_Transitive     0x0080   /* Transitive constraints */
 #define SQLITE_OmitNoopJoin   0x0100   /* Omit unused tables in joins */
 #define SQLITE_CountOfView    0x0200   /* The count-of-view optimization */
 #define SQLITE_CursorHints    0x0400   /* Add OP_CursorHint opcodes */
-#define SQLITE_Stat34         0x0800   /* Use STAT4 data */
-   /* TH3 expects the Stat34  ^^^^^^ value to be 0x0800.  Don't change it */
+#define SQLITE_Stat4          0x0800   /* Use STAT4 data */
+   /* TH3 expects the Stat4   ^^^^^^ value to be 0x0800.  Don't change it */
 #define SQLITE_PushDown       0x1000   /* The push-down optimization */
 #define SQLITE_SimplifyJoin   0x2000   /* Convert LEFT JOIN to JOIN */
 #define SQLITE_SkipScan       0x4000   /* Skip-scans */
 #define SQLITE_PropagateConst 0x8000   /* The constant propagation opt */
 #define SQLITE_AllOpts        0xffff   /* All optimizations */

Index: src/test1.c
==================================================================
--- src/test1.c
+++ src/test1.c
@@ -7171,11 +7171,11 @@
     { "distinct-opt",        SQLITE_DistinctOpt    },
     { "cover-idx-scan",      SQLITE_CoverIdxScan   },
     { "order-by-idx-join",   SQLITE_OrderByIdxJoin },
     { "transitive",          SQLITE_Transitive     },
     { "omit-noop-join",      SQLITE_OmitNoopJoin   },
-    { "stat4",               SQLITE_Stat34         },
+    { "stat4",               SQLITE_Stat4          },
     { "skip-scan",           SQLITE_SkipScan       },
   };
 
   if( objc!=4 ){
     Tcl_WrongNumArgs(interp, 1, objv, "DB OPT BOOLEAN");

Index: src/where.c
==================================================================
--- src/where.c
+++ src/where.c
@@ -1472,12 +1472,12 @@
 
 #ifdef SQLITE_ENABLE_STAT4
   Index *p = pLoop->u.btree.pIndex;
   int nEq = pLoop->u.btree.nEq;
 
-  if( p->nSample>0 && nEq<p->nSampleCol
-   && OptimizationEnabled(pParse->db, SQLITE_Stat34)
+  if( p->nSample>0 && ALWAYS(nEq<p->nSampleCol)
+   && OptimizationEnabled(pParse->db, SQLITE_Stat4)
   ){
     if( nEq==pBuilder->nRecValid ){
       UnpackedRecord *pRec = pBuilder->pRec;
       tRowcnt a[2];
       int nBtm = pLoop->u.btree.nBtm;
@@ -2631,11 +2631,11 @@
         tRowcnt nOut = 0;
         if( nInMul==0 
          && pProbe->nSample 
          && pNew->u.btree.nEq<=pProbe->nSampleCol
          && ((eOp & WO_IN)==0 || !ExprHasProperty(pTerm->pExpr, EP_xIsSelect))
-         && OptimizationEnabled(db, SQLITE_Stat34)
+         && OptimizationEnabled(db, SQLITE_Stat4)
         ){
           Expr *pExpr = pTerm->pExpr;
           if( (eOp & (WO_EQ|WO_ISNULL|WO_IS))!=0 ){
             testcase( eOp & WO_EQ );
             testcase( eOp & WO_IS );

Index: src/whereexpr.c
==================================================================
--- src/whereexpr.c
+++ src/whereexpr.c
@@ -1391,11 +1391,11 @@
   */
   if( pExpr->op==TK_NOTNULL
    && pExpr->pLeft->op==TK_COLUMN
    && pExpr->pLeft->iColumn>=0
    && !ExprHasProperty(pExpr, EP_FromJoin)
-   && OptimizationEnabled(db, SQLITE_Stat34)
+   && OptimizationEnabled(db, SQLITE_Stat4)
   ){
     Expr *pNewExpr;
     Expr *pLeft = pExpr->pLeft;
     int idxNew;
     WhereTerm *pNewTerm;