implement BestIndex estimated cost and usable constraint for when rep… (

#153)

* implement BestIndex estimated cost and usable constraint for when repository is supplied

* same fix for `refs` table

* rm the estimated cost changes for now

extensions/internal/git/log.go

@@ -94,6 +94,11 @@ func (tab *gitLogTable) BestIndex(input *sqlite.IndexInfoInput) (*sqlite.IndexIn
 			return nil, sqlite.SQLITE_CONSTRAINT
 		}
 
+		// if repository is provided, it must be usable
+		if idx == 9 && !constraint.Usable {
+			return nil, sqlite.SQLITE_CONSTRAINT
+		}
+
 		if !constraint.Usable {
 			continue
 		}

extensions/internal/git/refs.go

@@ -55,6 +55,11 @@ func (tab *gitRefTable) BestIndex(input *sqlite.IndexInfoInput) (*sqlite.IndexIn
 	out.ConstraintUsage = make([]*sqlite.ConstraintUsage, len(input.Constraints))
 
 	for i, constraint := range input.Constraints {
+		// if repository is provided, it must be usable
+		if constraint.ColumnIndex == 6 && !constraint.Usable {
+			return nil, sqlite.SQLITE_CONSTRAINT
+		}
+
 		if !constraint.Usable {
 			continue // we do not support unusable constraint at all
 		}