wip.diff

diff --git a/exp/ingest/io/postgres_temp_set.go b/exp/ingest/io/postgres_temp_set.go
index 4ca7432b..3d097a7c 100644
--- a/exp/ingest/io/postgres_temp_set.go
+++ b/exp/ingest/io/postgres_temp_set.go
@@ -31,7 +31,7 @@ const (
 // If `Session` is passed, it will be cloned.
 type PostgresTempSet struct {
 	DSN     string
-	Session *db.Session
+	Session db.SessionInterface
 
 	afterFirstDump bool
 	// cache can contain both true and false values. false values can be set
diff --git a/services/horizon/internal/db2/history/main.go b/services/horizon/internal/db2/history/main.go
index 9847f47f..e763d208 100644
--- a/services/horizon/internal/db2/history/main.go
+++ b/services/horizon/internal/db2/history/main.go
@@ -454,6 +454,8 @@ type Q struct {
 	*db.Session
 }
 
+var _ db.SessionInterface = (*Q)(nil)
+
 // QSigners defines signer related queries.
 type QSigners interface {
 	GetLastLedgerExpIngestNonBlocking() (uint32, error)
diff --git a/services/horizon/internal/expingest/main.go b/services/horizon/internal/expingest/main.go
index 1be00df1..835aab8c 100644
--- a/services/horizon/internal/expingest/main.go
+++ b/services/horizon/internal/expingest/main.go
@@ -93,7 +93,7 @@ type dbQ interface {
 
 	Begin() error
 	Commit() error
-	Clone() *db.Session
+	Clone() db.SessionInterface
 	Rollback() error
 	GetTx() *sqlx.Tx
 	GetExpIngestVersion() (int, error)
@@ -184,7 +184,8 @@ func NewSystem(config Config) (*System, error) {
 		return nil, errors.Wrap(err, "error creating ledger backend")
 	}
 
-	historyQ := &history.Q{config.HistorySession.Clone()}
+	clone, _ := config.HistorySession.Clone()
+	historyQ := &history.Q{&clone}
 
 	historyAdapter := adapters.MakeHistoryArchiveAdapter(archive)
 
diff --git a/services/horizon/internal/expingest/main_test.go b/services/horizon/internal/expingest/main_test.go
index 4e121723..f54d2c42 100644
--- a/services/horizon/internal/expingest/main_test.go
+++ b/services/horizon/internal/expingest/main_test.go
@@ -4,7 +4,6 @@ import (
 	"context"
 	"testing"
 
-	"github.com/jmoiron/sqlx"
 	"github.com/stellar/go/services/horizon/internal/db2/history"
 	"github.com/stellar/go/support/db"
 	"github.com/stellar/go/support/errors"
@@ -45,6 +44,7 @@ func TestStateMachineRunReturnsErrorWhenNextStateIsShutdownWithError(t *testing.
 
 type mockDBQ struct {
 	mock.Mock
+	db.MockSession
 
 	history.MockQAccounts
 	history.MockQAssetStats
@@ -58,34 +58,13 @@ type mockDBQ struct {
 	history.MockQTrustLines
 }
 
-func (m *mockDBQ) Begin() error {
-	args := m.Called()
-	return args.Error(0)
-}
-
-func (m *mockDBQ) Clone() *db.Session {
-	args := m.Called()
-	return args.Get(0).(*db.Session)
-}
+var _ db.SessionInterface = (*mockDBQ)(nil)
 
 func (m *mockDBQ) Commit() error {
 	args := m.Called()
 	return args.Error(0)
 }
 
-func (m *mockDBQ) Rollback() error {
-	args := m.Called()
-	return args.Error(0)
-}
-
-func (m *mockDBQ) GetTx() *sqlx.Tx {
-	args := m.Called()
-	if args.Get(0) == nil {
-		return nil
-	}
-	return args.Get(0).(*sqlx.Tx)
-}
-
 func (m *mockDBQ) GetLastLedgerExpIngest() (uint32, error) {
 	args := m.Called()
 	return args.Get(0).(uint32), args.Error(1)
diff --git a/support/db/main.go b/support/db/main.go
index b625b174..05bb8547 100644
--- a/support/db/main.go
+++ b/support/db/main.go
@@ -134,13 +134,14 @@ type SessionInterface interface {
 	Begin() error
 	Rollback() error
 	TruncateTables(tables []string) error
-	Clone() *Session
+	Clone() SessionInterface
 	Close() error
 	Get(dest interface{}, query squirrel.Sqlizer) error
 	GetRaw(dest interface{}, query string, args ...interface{}) error
 	Select(dest interface{}, query squirrel.Sqlizer) error
 	SelectRaw(dest interface{}, query string, args ...interface{}) error
 	GetTable(name string) *Table
+	GetTx() *sqlx.Tx
 	Exec(query squirrel.Sqlizer) (sql.Result, error)
 	ExecRaw(query string, args ...interface{}) (sql.Result, error)
 	NoRows(err error) bool
diff --git a/support/db/mock_session.go b/support/db/mock_session.go
index fe96d622..029c3026 100644
--- a/support/db/mock_session.go
+++ b/support/db/mock_session.go
@@ -5,6 +5,7 @@ import (
 
 	"github.com/Masterminds/squirrel"
 	sq "github.com/Masterminds/squirrel"
+	"github.com/jmoiron/sqlx"
 	"github.com/stretchr/testify/mock"
 )
 
@@ -29,9 +30,9 @@ func (m *MockSession) TruncateTables(tables []string) error {
 	return args.Error(0)
 }
 
-func (m *MockSession) Clone() *Session {
+func (m *MockSession) Clone() SessionInterface {
 	args := m.Called()
-	return args.Get(0).(*Session)
+	return args.Get(0).(SessionInterface)
 }
 
 func (m *MockSession) Close() error {
@@ -49,6 +50,14 @@ func (m *MockSession) GetRaw(dest interface{}, query string, args ...interface{}
 	return argss.Error(0)
 }
 
+func (m *MockSession) GetTx() *sqlx.Tx {
+	args := m.Called()
+	if args.Get(0) == nil {
+		return nil
+	}
+	return args.Get(0).(*sqlx.Tx)
+}
+
 func (m *MockSession) Select(dest interface{}, query squirrel.Sqlizer) error {
 	argss := m.Called(dest, query)
 	return argss.Error(0)
diff --git a/support/db/session.go b/support/db/session.go
index 799af9fc..b4df3b54 100644
--- a/support/db/session.go
+++ b/support/db/session.go
@@ -63,7 +63,7 @@ func (s *Session) GetTx() *sqlx.Tx {
 // Clone clones the receiver, returning a new instance backed by the same
 // context and db. The result will not be bound to any transaction that the
 // source is currently within.
-func (s *Session) Clone() *Session {
+func (s *Session) Clone() SessionInterface {
 	return &Session{
 		DB:  s.DB,
 		Ctx: s.Ctx,