Add a small cost penalty to sorting to bias the query planner in favor of

plans that do not require a final sorting pass.

FossilOrigin-Name: 85b9beb4605eb0cfe2ed063c2a1925186c9e37031f78c875e60a347cce891638

1 files changed, 5 insertions, 1 deletions

diff --git a/src/where.c b/src/where.c
index b7e51f3d9..722a0062a 100644
--- a/src/where.c
+++ b/src/where.c
@@ -4056,7 +4056,11 @@ static int wherePathSolver(WhereInfo *pWInfo, LogEst nRowEst){
                 pWInfo, nRowEst, nOrderBy, isOrdered
             );
           }
-          rCost = sqlite3LogEstAdd(rUnsorted, aSortCost[isOrdered]);
+          /* TUNING:  Add a small extra penalty (5) to sorting as an
+          ** extra encouragment to the query planner to select a plan
+          ** where the rows emerge in the correct order without any sorting
+          ** required. */
+          rCost = sqlite3LogEstAdd(rUnsorted, aSortCost[isOrdered]) + 5;
 
           WHERETRACE(0x002,
               ("---- sort cost=%-3d (%d/%d) increases cost %3d to %-3d\n",