Index: src/where.c
==================================================================
--- src/where.c
+++ src/where.c
@@ -3790,10 +3790,20 @@
   ** below.  */
   LogEst rScale, rSortCost;
   assert( nOrderBy>0 && 66==sqlite3LogEst(100) );
   rScale = sqlite3LogEst((nOrderBy-nSorted)*100/nOrderBy) - 66;
   rSortCost = nRow + rScale + 16;
+
+  /* For wide sorts (many payload columns) increase the sorting cost
+  ** to account for the additional I/O used by the external sorting
+  ** algorithm when it flushes PMAs to disk.
+  */
+  if( pWInfo->pResultSet
+   && pWInfo->pResultSet->nExpr>6
+  ){
+    rSortCost += sqlite3LogEst(pWInfo->pResultSet->nExpr) - 26;
+  }
 
   /* Multiple by log(M) where M is the number of output rows.
   ** Use the LIMIT for M if it is smaller */
   if( (pWInfo->wctrlFlags & WHERE_USE_LIMIT)!=0 && pWInfo->iLimit<nRow ){
     nRow = pWInfo->iLimit;