diff --git a/src/github.com/matrix-org/dendrite/syncapi/storage/account_data_table.go b/src/github.com/matrix-org/dendrite/syncapi/storage/account_data_table.go
index 4a23d697741d12292eb924f32911b3f88d8479b1..72aaf3551c2590628c27faeff537707112726b10 100644
--- a/src/github.com/matrix-org/dendrite/syncapi/storage/account_data_table.go
+++ b/src/github.com/matrix-org/dendrite/syncapi/storage/account_data_table.go
@@ -18,14 +18,20 @@ import (
 	"context"
 	"database/sql"
 
+	"github.com/matrix-org/dendrite/common"
+
 	"github.com/matrix-org/dendrite/syncapi/types"
 )
 
 const accountDataSchema = `
--- Stores the users account data
+-- This sequence is shared between all the tables generated from kafka logs.
+CREATE SEQUENCE IF NOT EXISTS syncapi_stream_id;
+
+-- Stores the types of account data that a user set has globally and in each room
+-- and the stream ID when that type was last updated.
 CREATE TABLE IF NOT EXISTS syncapi_account_data_type (
-    -- The highest numeric ID from the output_room_events at the time of saving the data
-    id BIGINT,
+    -- An incrementing ID which denotes the position in the log that this event resides at.
+    id BIGINT PRIMARY KEY DEFAULT nextval('syncapi_stream_id'),
     -- ID of the user the data belongs to
     user_id TEXT NOT NULL,
     -- ID of the room the data is related to (empty string if not related to a specific room)
@@ -33,8 +39,6 @@ CREATE TABLE IF NOT EXISTS syncapi_account_data_type (
     -- Type of the data
     type TEXT NOT NULL,
 
-    PRIMARY KEY(user_id, room_id, type),
-
     -- We don't want two entries of the same type for the same user
     CONSTRAINT syncapi_account_data_unique UNIQUE (user_id, room_id, type)
 );
@@ -43,18 +47,23 @@ CREATE UNIQUE INDEX IF NOT EXISTS syncapi_account_data_id_idx ON syncapi_account
 `
 
 const insertAccountDataSQL = "" +
-	"INSERT INTO syncapi_account_data_type (id, user_id, room_id, type) VALUES ($1, $2, $3, $4)" +
+	"INSERT INTO syncapi_account_data_type (user_id, room_id, type) VALUES ($1, $2, $3)" +
 	" ON CONFLICT ON CONSTRAINT syncapi_account_data_unique" +
-	" DO UPDATE SET id = EXCLUDED.id"
+	" DO UPDATE SET id = EXCLUDED.id" +
+	" RETURNING id"
 
 const selectAccountDataInRangeSQL = "" +
 	"SELECT room_id, type FROM syncapi_account_data_type" +
 	" WHERE user_id = $1 AND id > $2 AND id <= $3" +
 	" ORDER BY id ASC"
 
+const selectMaxAccountDataIDSQL = "" +
+	"SELECT MAX(id) FROM syncapi_account_data_type"
+
 type accountDataStatements struct {
 	insertAccountDataStmt        *sql.Stmt
 	selectAccountDataInRangeStmt *sql.Stmt
+	selectMaxAccountDataIDStmt   *sql.Stmt
 }
 
 func (s *accountDataStatements) prepare(db *sql.DB) (err error) {
@@ -68,15 +77,17 @@ func (s *accountDataStatements) prepare(db *sql.DB) (err error) {
 	if s.selectAccountDataInRangeStmt, err = db.Prepare(selectAccountDataInRangeSQL); err != nil {
 		return
 	}
+	if s.selectMaxAccountDataIDStmt, err = db.Prepare(selectMaxAccountDataIDSQL); err != nil {
+		return
+	}
 	return
 }
 
 func (s *accountDataStatements) insertAccountData(
 	ctx context.Context,
-	pos types.StreamPosition,
 	userID, roomID, dataType string,
-) (err error) {
-	_, err = s.insertAccountDataStmt.ExecContext(ctx, pos, userID, roomID, dataType)
+) (pos int64, err error) {
+	s.insertAccountDataStmt.QueryRowContext(ctx, userID, roomID, dataType).Scan(&pos)
 	return
 }
 
@@ -116,3 +127,15 @@ func (s *accountDataStatements) selectAccountDataInRange(
 
 	return
 }
+
+func (s *accountDataStatements) selectMaxAccountDataID(
+	ctx context.Context, txn *sql.Tx,
+) (id int64, err error) {
+	var nullableID sql.NullInt64
+	stmt := common.TxStmt(txn, s.selectMaxAccountDataIDStmt)
+	err = stmt.QueryRowContext(ctx).Scan(&nullableID)
+	if nullableID.Valid {
+		id = nullableID.Int64
+	}
+	return
+}
diff --git a/src/github.com/matrix-org/dendrite/syncapi/storage/output_room_events_table.go b/src/github.com/matrix-org/dendrite/syncapi/storage/output_room_events_table.go
index 7ae24990acb633ae5995fafe06a11fa8db0f11b4..660a3074dfd22d4237542b7f0c56e7b9bf71109d 100644
--- a/src/github.com/matrix-org/dendrite/syncapi/storage/output_room_events_table.go
+++ b/src/github.com/matrix-org/dendrite/syncapi/storage/output_room_events_table.go
@@ -26,12 +26,15 @@ import (
 )
 
 const outputRoomEventsSchema = `
+-- This sequence is shared between all the tables generated from kafka logs.
+CREATE SEQUENCE IF NOT EXISTS syncapi_stream_id;
+
 -- Stores output room events received from the roomserver.
 CREATE TABLE IF NOT EXISTS syncapi_output_room_events (
     -- An incrementing ID which denotes the position in the log that this event resides at.
     -- NB: 'serial' makes no guarantees to increment by 1 every time, only that it increments.
     --     This isn't a problem for us since we just want to order by this field.
-    id BIGSERIAL PRIMARY KEY,
+    id BIGINT PRIMARY KEY DEFAULT nextval('syncapi_stream_id'),
     -- The event ID for the event
     event_id TEXT NOT NULL,
     -- The 'room_id' key for the event.
@@ -60,7 +63,7 @@ const selectRecentEventsSQL = "" +
 	" WHERE room_id = $1 AND id > $2 AND id <= $3" +
 	" ORDER BY id DESC LIMIT $4"
 
-const selectMaxIDSQL = "" +
+const selectMaxEventIDSQL = "" +
 	"SELECT MAX(id) FROM syncapi_output_room_events"
 
 // In order for us to apply the state updates correctly, rows need to be ordered in the order they were received (id).
@@ -73,7 +76,7 @@ const selectStateInRangeSQL = "" +
 type outputRoomEventsStatements struct {
 	insertEventStmt        *sql.Stmt
 	selectEventsStmt       *sql.Stmt
-	selectMaxIDStmt        *sql.Stmt
+	selectMaxEventIDStmt   *sql.Stmt
 	selectRecentEventsStmt *sql.Stmt
 	selectStateInRangeStmt *sql.Stmt
 }
@@ -89,7 +92,7 @@ func (s *outputRoomEventsStatements) prepare(db *sql.DB) (err error) {
 	if s.selectEventsStmt, err = db.Prepare(selectEventsSQL); err != nil {
 		return
 	}
-	if s.selectMaxIDStmt, err = db.Prepare(selectMaxIDSQL); err != nil {
+	if s.selectMaxEventIDStmt, err = db.Prepare(selectMaxEventIDSQL); err != nil {
 		return
 	}
 	if s.selectRecentEventsStmt, err = db.Prepare(selectRecentEventsSQL); err != nil {
@@ -170,11 +173,11 @@ func (s *outputRoomEventsStatements) selectStateInRange(
 // MaxID returns the ID of the last inserted event in this table. 'txn' is optional. If it is not supplied,
 // then this function should only ever be used at startup, as it will race with inserting events if it is
 // done afterwards. If there are no inserted events, 0 is returned.
-func (s *outputRoomEventsStatements) selectMaxID(
+func (s *outputRoomEventsStatements) selectMaxEventID(
 	ctx context.Context, txn *sql.Tx,
 ) (id int64, err error) {
 	var nullableID sql.NullInt64
-	stmt := common.TxStmt(txn, s.selectMaxIDStmt)
+	stmt := common.TxStmt(txn, s.selectMaxEventIDStmt)
 	err = stmt.QueryRowContext(ctx).Scan(&nullableID)
 	if nullableID.Valid {
 		id = nullableID.Int64
diff --git a/src/github.com/matrix-org/dendrite/syncapi/storage/syncserver.go b/src/github.com/matrix-org/dendrite/syncapi/storage/syncserver.go
index 6594b938c8c5075f7ca3dfe8b565bedca9a2019d..a26b14c0e1bd5cd8396dc7c4591eb0a2380f85f1 100644
--- a/src/github.com/matrix-org/dendrite/syncapi/storage/syncserver.go
+++ b/src/github.com/matrix-org/dendrite/syncapi/storage/syncserver.go
@@ -174,11 +174,24 @@ func (d *SyncServerDatabase) SetPartitionOffset(topic string, partition int32, o
 
 // SyncStreamPosition returns the latest position in the sync stream. Returns 0 if there are no events yet.
 func (d *SyncServerDatabase) SyncStreamPosition(ctx context.Context) (types.StreamPosition, error) {
-	id, err := d.events.selectMaxID(ctx, nil)
+	return d.syncStreamPositionTx(ctx, nil)
+}
+
+func (d *SyncServerDatabase) syncStreamPositionTx(
+	ctx context.Context, txn *sql.Tx,
+) (types.StreamPosition, error) {
+	maxID, err := d.events.selectMaxEventID(ctx, txn)
+	if err != nil {
+		return 0, err
+	}
+	maxAccountDataID, err := d.accountData.selectMaxAccountDataID(ctx, txn)
 	if err != nil {
-		return types.StreamPosition(0), err
+		return 0, err
+	}
+	if maxAccountDataID > maxID {
+		maxID = maxAccountDataID
 	}
-	return types.StreamPosition(id), nil
+	return types.StreamPosition(maxID), nil
 }
 
 // IncrementalSync returns all the data needed in order to create an incremental sync response.
@@ -271,11 +284,10 @@ func (d *SyncServerDatabase) CompleteSync(
 	defer common.EndTransaction(txn, &succeeded)
 
 	// Get the current stream position which we will base the sync response on.
-	id, err := d.events.selectMaxID(ctx, txn)
+	pos, err := d.syncStreamPositionTx(ctx, txn)
 	if err != nil {
 		return nil, err
 	}
-	pos := types.StreamPosition(id)
 
 	// Extract room state and recent events for all rooms the user is joined to.
 	roomIDs, err := d.roomstate.selectRoomIDsWithMembership(ctx, txn, userID, "join")
@@ -348,13 +360,8 @@ func (d *SyncServerDatabase) GetAccountDataInRange(
 func (d *SyncServerDatabase) UpsertAccountData(
 	ctx context.Context, userID, roomID, dataType string,
 ) (types.StreamPosition, error) {
-	pos, err := d.SyncStreamPosition(ctx)
-	if err != nil {
-		return pos, err
-	}
-
-	err = d.accountData.insertAccountData(ctx, pos, userID, roomID, dataType)
-	return pos, err
+	pos, err := d.accountData.insertAccountData(ctx, userID, roomID, dataType)
+	return types.StreamPosition(pos), err
 }
 
 func (d *SyncServerDatabase) addInvitesToResponse(