diff --git a/syncapi/storage/postgres/relations_table.go b/syncapi/storage/postgres/relations_table.go
new file mode 100644
index 000000000..acc156e91
--- /dev/null
+++ b/syncapi/storage/postgres/relations_table.go
@@ -0,0 +1,161 @@
+// Copyright 2017-2018 New Vector Ltd
+// Copyright 2019-2020 The Matrix.org Foundation C.I.C.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package postgres
+
+import (
+	"context"
+	"database/sql"
+
+	"github.com/matrix-org/dendrite/internal"
+	"github.com/matrix-org/dendrite/internal/sqlutil"
+	"github.com/matrix-org/dendrite/syncapi/storage/tables"
+	"github.com/matrix-org/dendrite/syncapi/types"
+)
+
+const relationsSchema = `
+CREATE TABLE IF NOT EXISTS syncapi_relations (
+	id BIGINT PRIMARY KEY DEFAULT nextval('syncapi_relation_id'),
+	room_id TEXT NOT NULL,
+	event_id TEXT NOT NULL,
+	child_event_id TEXT NOT NULL,
+	rel_type TEXT NOT NULL,
+	CONSTRAINT syncapi_relations_unique UNIQUE (room_id, event_id, child_event_id, rel_type)
+);
+`
+
+const insertRelationSQL = "" +
+	"INSERT INTO syncapi_relations (" +
+	"  room_id, event_id, child_event_id, rel_type" +
+	") VALUES ($1, $2, $3, $4) RETURNING id"
+
+const deleteRelationSQL = "" +
+	"DELETE FROM syncapi_relations WHERE event_id = $1"
+
+const selectRelationsInRangeSQL = "" +
+	"SELECT id, room_id, child_event_id, rel_type FROM syncapi_relations" +
+	" WHERE room_id = $1 AND event_id = $2 AND id > $3 AND id <= $4" +
+	" ORDER BY id DESC"
+
+const selectRelationsByTypeInRangeSQL = "" +
+	"SELECT id, room_id, child_event_id, rel_type FROM syncapi_relations" +
+	" WHERE room_id = $1 AND event_id = $2 AND rel_type = $3 AND id > $4 AND id <= $5" +
+	" ORDER BY id DESC"
+
+const selectMaxRelationIDSQL = "" +
+	"SELECT MAX(id) FROM syncapi_relations"
+
+type relationsStatements struct {
+	insertRelationStmt               *sql.Stmt
+	selectRelationsInRangeStmt       *sql.Stmt
+	selectRelationsByTypeInRangeStmt *sql.Stmt
+	deleteRelationStmt               *sql.Stmt
+	selectMaxRelationIDStmt          *sql.Stmt
+}
+
+func NewPostgresRelationsTable(db *sql.DB) (tables.Relations, error) {
+	s := &relationsStatements{}
+	_, err := db.Exec(relationsSchema)
+	if err != nil {
+		return nil, err
+	}
+	if s.insertRelationStmt, err = db.Prepare(insertRelationSQL); err != nil {
+		return nil, err
+	}
+	if s.selectRelationsInRangeStmt, err = db.Prepare(selectRelationsInRangeSQL); err != nil {
+		return nil, err
+	}
+	if s.selectRelationsByTypeInRangeStmt, err = db.Prepare(selectRelationsByTypeInRangeSQL); err != nil {
+		return nil, err
+	}
+	if s.deleteRelationStmt, err = db.Prepare(deleteRelationSQL); err != nil {
+		return nil, err
+	}
+	if s.selectMaxRelationIDStmt, err = db.Prepare(selectMaxRelationIDSQL); err != nil {
+		return nil, err
+	}
+	return s, nil
+}
+
+func (s *relationsStatements) InsertRelation(
+	ctx context.Context, txn *sql.Tx, roomID, eventID, childEventID, relType string,
+) (streamPos types.StreamPosition, err error) {
+	err = sqlutil.TxStmt(txn, s.insertRelationStmt).QueryRowContext(
+		ctx, roomID, eventID, childEventID, relType,
+	).Scan(&streamPos)
+	return
+}
+
+func (s *relationsStatements) DeleteRelation(
+	ctx context.Context, txn *sql.Tx, roomID, eventID, childEventID, relType string,
+) error {
+	stmt := sqlutil.TxStmt(txn, s.deleteRelationStmt)
+	_, err := stmt.ExecContext(
+		ctx, roomID, eventID, childEventID, relType,
+	)
+	return err
+}
+
+// SelectRelationsInRange returns a map rel_type -> []child_event_id
+func (s *relationsStatements) SelectRelationsInRange(
+	ctx context.Context, txn *sql.Tx, roomID, eventID, relType string, r types.Range,
+) (map[string][]string, types.StreamPosition, error) {
+	var lastPos types.StreamPosition
+	var rows *sql.Rows
+	var err error
+	if relType != "" {
+		stmt := sqlutil.TxStmt(txn, s.selectRelationsByTypeInRangeStmt)
+		rows, err = stmt.QueryContext(ctx, roomID, eventID, relType, r.Low(), r.High())
+	} else {
+		stmt := sqlutil.TxStmt(txn, s.selectRelationsInRangeStmt)
+		rows, err = stmt.QueryContext(ctx, roomID, eventID, r.Low(), r.High())
+	}
+	if err != nil {
+		return nil, lastPos, err
+	}
+	defer internal.CloseAndLogIfError(ctx, rows, "selectRelationsInRange: rows.close() failed")
+	result := map[string][]string{}
+	for rows.Next() {
+		var (
+			id           types.StreamPosition
+			roomID       string
+			childEventID string
+			relType      string
+		)
+		if err = rows.Scan(&id, &roomID, &childEventID, &relType); err != nil {
+			return nil, lastPos, err
+		}
+		if id > lastPos {
+			lastPos = id
+		}
+		result[relType] = append(result[relType], childEventID)
+	}
+	if lastPos == 0 {
+		lastPos = r.To
+	}
+	return result, lastPos, rows.Err()
+}
+
+func (s *relationsStatements) SelectMaxRelationID(
+	ctx context.Context, txn *sql.Tx,
+) (id int64, err error) {
+	var nullableID sql.NullInt64
+	stmt := sqlutil.TxStmt(txn, s.selectMaxRelationIDStmt)
+	err = stmt.QueryRowContext(ctx).Scan(&nullableID)
+	if nullableID.Valid {
+		id = nullableID.Int64
+	}
+	return
+}
diff --git a/syncapi/storage/tables/interface.go b/syncapi/storage/tables/interface.go
index 2fdc3cfbb..2d6cd9357 100644
--- a/syncapi/storage/tables/interface.go
+++ b/syncapi/storage/tables/interface.go
@@ -206,3 +206,10 @@ type Presence interface {
 	GetMaxPresenceID(ctx context.Context, txn *sql.Tx) (pos types.StreamPosition, err error)
 	GetPresenceAfter(ctx context.Context, txn *sql.Tx, after types.StreamPosition, filter gomatrixserverlib.EventFilter) (presences map[string]*types.PresenceInternal, err error)
 }
+
+type Relations interface {
+	InsertRelation(ctx context.Context, txn *sql.Tx, roomID, eventID, childEventID, relType string) (streamPos types.StreamPosition, err error)
+	DeleteRelation(ctx context.Context, txn *sql.Tx, roomID, eventID, childEventID, relType string) error
+	SelectRelationsInRange(ctx context.Context, txn *sql.Tx, roomID, eventID, relType string, r types.Range) (map[string][]string, types.StreamPosition, error)
+	SelectMaxRelationID(ctx context.Context, txn *sql.Tx) (id int64, err error)
+}