diff --git a/pkg/sql/utils.go b/pkg/sql/utils.go
index 420107602..513f85d91 100644
--- a/pkg/sql/utils.go
+++ b/pkg/sql/utils.go
@@ -1,10 +1,10 @@
 package sql
 
 import (
+	"github.com/golang/geo/s2"
 	"github.com/interuss/dss/pkg/geo"
 	"github.com/interuss/stacktrace"
-
-	"github.com/golang/geo/s2"
+	"slices"
 )
 
 func CellUnionToCellIds(cu s2.CellUnion) []int64 {
@@ -13,6 +13,8 @@ func CellUnionToCellIds(cu s2.CellUnion) []int64 {
 		// TODO consider validating the cell here: it is/was done in many similar conversion loops
 		pgCids[i] = int64(cell)
 	}
+	// Sort the cell IDs for optimisation purpose (see https://github.com/interuss/dss/issues/814)
+	slices.Sort(pgCids)
 	return pgCids
 }
 
@@ -24,5 +26,7 @@ func CellUnionToCellIdsWithValidation(cu s2.CellUnion) ([]int64, error) {
 		}
 		pgCids[i] = int64(cell)
 	}
+	// Sort the cell IDs for optimisation purpose (see https://github.com/interuss/dss/issues/814)
+	slices.Sort(pgCids)
 	return pgCids, nil
 }