Use only a single query for GetIDWithMaxHeight

api/grpcserver/v2alpha1/activation.go

@@ -242,15 +242,10 @@ func (s *ActivationService) ActivationsCount(
 }
 
 func (s *ActivationService) Highest(
-	ctx context.Context,
+	_ context.Context,
 	_ *spacemeshv2alpha1.HighestRequest,
 ) (*spacemeshv2alpha1.HighestResponse, error) {
-	var highest types.ATXID
-	err := s.db.WithTxImmediate(ctx, func(tx sql.Transaction) error {
-		var err error
-		highest, err = atxs.GetIDWithMaxHeight(tx, types.EmptyNodeID, atxs.FilterAll)
-		return err
-	})
+	highest, err := atxs.GetIDWithMaxHeight(s.db, types.EmptyNodeID, atxs.FilterAll)
 	if err != nil {
 		return &spacemeshv2alpha1.HighestResponse{
 			Activation: &spacemeshv2alpha1.Activation{

api/grpcserver/v2beta1/activation.go

@@ -242,15 +242,10 @@ func (s *ActivationService) ActivationsCount(
 }
 
 func (s *ActivationService) Highest(
-	ctx context.Context,
+	_ context.Context,
 	_ *spacemeshv2beta1.HighestRequest,
 ) (*spacemeshv2beta1.HighestResponse, error) {
-	var highest types.ATXID
-	err := s.db.WithTxImmediate(ctx, func(tx sql.Transaction) error {
-		var err error
-		highest, err = atxs.GetIDWithMaxHeight(tx, types.EmptyNodeID, atxs.FilterAll)
-		return err
-	})
+	highest, err := atxs.GetIDWithMaxHeight(s.db, types.EmptyNodeID, atxs.FilterAll)
 	if err != nil {
 		return &spacemeshv2beta1.HighestResponse{
 			Activation: &spacemeshv2beta1.Activation{

datastore/store.go

@@ -217,13 +217,7 @@ func (db *CachedDB) IterateMalfeasanceProofs(
 // MaxHeightAtx returns the ATX ID with the maximum height.
 // Deprecated: replaced by atxs.GetIDWithMaxHeight.
 func (db *CachedDB) MaxHeightAtx() (types.ATXID, error) {
-	var id types.ATXID
-	err := db.WithTxImmediate(context.Background(), func(tx sql.Transaction) error {
-		var err error
-		id, err = atxs.GetIDWithMaxHeight(tx, types.EmptyNodeID, atxs.FilterAll)
-		return err
-	})
-	return id, err
+	return atxs.GetIDWithMaxHeight(db, types.EmptyNodeID, atxs.FilterAll)
 }
 
 // Hint marks which DB should be queried for a certain provided hash.

sql/atxs/atxs.go

@@ -518,27 +518,15 @@ func FilterAll(types.ATXID) bool { return true }
 // highest ticked atx still in previous epoch and the atxs building on top of it have not been published yet.
 // Selecting from the last two epochs to strike a balance between being fair to honest miners while not giving
 // unfair advantage for malicious actors who retroactively publish a high tick atx many epochs back.
-func GetIDWithMaxHeight(tx sql.Transaction, pref types.NodeID, filter Filter) (types.ATXID, error) {
+func GetIDWithMaxHeight(db sql.Executor, pref types.NodeID, filter Filter) (types.ATXID, error) {
 	if filter == nil {
 		filter = FilterAll
 	}
 
-	// find max epoch
-	var maxEpoch types.EpochID
-	if _, err := tx.Exec("select max(epoch) from atxs;", nil, func(stmt *sql.Statement) bool {
-		maxEpoch = types.EpochID(uint32(stmt.ColumnInt64(0)))
-		return false
-	}); err != nil {
-		return types.ATXID{}, fmt.Errorf("selecting max epoch: %w", err)
-	}
-
 	var (
 		rst     types.ATXID
 		highest uint64
 	)
-	enc := func(stmt *sql.Statement) {
-		stmt.BindInt64(1, int64(maxEpoch-1))
-	}
 	dec := func(stmt *sql.Statement) bool {
 		var id types.ATXID
 		stmt.ColumnBytes(0, id[:])
@@ -567,20 +555,21 @@ func GetIDWithMaxHeight(tx sql.Transaction, pref types.NodeID, filter Filter) (t
 		return true
 	}
 
-	_, err := tx.Exec(`
+	_, err := db.Exec(`
+		WITH max_epoch AS (SELECT MAX(epoch) AS max_epoch FROM atxs)
 		SELECT a.id, a.height, a.pubkey
 		FROM (
 			SELECT id, base_tick_height + tick_count AS height, pubkey, epoch
 			FROM atxs
-			WHERE epoch >= ?1
+			WHERE epoch >= (SELECT max_epoch FROM max_epoch)-1
 		) a
 		WHERE NOT EXISTS (
 			SELECT 1 FROM identities i WHERE i.pubkey = a.pubkey
 		) AND NOT EXISTS (
 		 	SELECT 1 FROM malfeasance m WHERE m.pubkey = a.pubkey
 		)
 		ORDER BY a.height DESC, a.epoch DESC
-	`, enc, dec)
+	`, nil, dec)
 	switch {
 	case err != nil:
 		return types.ATXID{}, fmt.Errorf("selecting high-tick atx: %w", err)

sql/atxs/atxs_test.go

@@ -941,14 +941,10 @@ func TestGetIDWithMaxHeight(t *testing.T) {
 			if tc.pref > 0 {
 				pref = sigs[tc.pref].NodeID()
 			}
-			var rst types.ATXID
-			err := db.WithTxImmediate(context.Background(), func(tx sql.Transaction) error {
-				var err error
-				rst, err = atxs.GetIDWithMaxHeight(tx, pref, func(id types.ATXID) bool {
-					_, ok := filtered[id]
-					return !ok
-				})
-				return err
+
+			rst, err := atxs.GetIDWithMaxHeight(db, pref, func(id types.ATXID) bool {
+				_, ok := filtered[id]
+				return !ok
 			})
 			if len(tc.atxs) == 0 || tc.expect < 0 {
 				require.ErrorIs(t, err, sql.ErrNotFound)