Because SQLite internally calculates query plan costs using a logarithmic scale, very large estimated sorting costs can cause all other estimated costs to be rounded down to zero. In these cases break ties between plans with the same total cost by comparing the costs with sorting excluded. This is an alternative fix for the same problem as addressed by [2af630c572].

FossilOrigin-Name: 299b9570279ded7158d22349ef93384286a5c755

src/whereInt.h

@@ -183,6 +183,7 @@ struct WherePath {
   Bitmask revLoop;      /* aLoop[]s that should be reversed for ORDER BY */
   LogEst nRow;          /* Estimated number of rows generated by this path */
   LogEst rCost;         /* Total cost of this path */
+  LogEst rUnsorted;     /* Total cost of this path ignoring sorting costs */
   i8 isOrdered;         /* No. of ORDER BY terms satisfied. -1 for unknown */
   WhereLoop **aLoop;    /* Array of WhereLoop objects implementing this path */
 };