diff --git a/roomserver/storage/postgres/deltas/20201028212440_add_forgotten_column.go b/roomserver/storage/postgres/deltas/20201028212440_add_forgotten_column.go
index 733f0fa1..f3bd8632 100644
--- a/roomserver/storage/postgres/deltas/20201028212440_add_forgotten_column.go
+++ b/roomserver/storage/postgres/deltas/20201028212440_add_forgotten_column.go
@@ -24,6 +24,7 @@ import (
 
 func LoadFromGoose() {
 	goose.AddMigration(UpAddForgottenColumn, DownAddForgottenColumn)
+	goose.AddMigration(UpStateBlocksRefactor, DownStateBlocksRefactor)
 }
 
 func LoadAddForgottenColumn(m *sqlutil.Migrations) {
diff --git a/roomserver/storage/postgres/deltas/20210416150927_state_blocks_refactor.go b/roomserver/storage/postgres/deltas/20210416150927_state_blocks_refactor.go
new file mode 100644
index 00000000..4aa3be5a
--- /dev/null
+++ b/roomserver/storage/postgres/deltas/20210416150927_state_blocks_refactor.go
@@ -0,0 +1,145 @@
+// Copyright 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 deltas
+
+import (
+	"context"
+	"database/sql"
+	"fmt"
+
+	"github.com/matrix-org/dendrite/internal"
+	"github.com/matrix-org/dendrite/internal/sqlutil"
+	"github.com/matrix-org/dendrite/roomserver/types"
+	"github.com/matrix-org/util"
+)
+
+func LoadStateBlocksRefactor(m *sqlutil.Migrations) {
+	m.AddMigration(UpStateBlocksRefactor, DownStateBlocksRefactor)
+}
+
+func UpStateBlocksRefactor(tx *sql.Tx) error {
+	if _, err := tx.Exec(`ALTER TABLE roomserver_state_block RENAME TO _roomserver_state_block;`); err != nil {
+		return fmt.Errorf("tx.Exec: %w", err)
+	}
+	if _, err := tx.Exec(`ALTER TABLE roomserver_state_snapshots RENAME TO _roomserver_state_snapshots;`); err != nil {
+		return fmt.Errorf("tx.Exec: %w", err)
+	}
+	_, err := tx.Exec(`
+		CREATE TABLE IF NOT EXISTS roomserver_state_block (
+			-- Local numeric ID for this state data.
+			state_block_nid bigserial PRIMARY KEY,
+			event_nids bigint[] NOT NULL,
+			UNIQUE (event_nids)
+		);
+	`)
+	if err != nil {
+		return fmt.Errorf("tx.Exec: %w", err)
+	}
+	_, err = tx.Exec(`
+		CREATE SEQUENCE IF NOT EXISTS roomserver_state_snapshot_nid_seq;
+		CREATE TABLE IF NOT EXISTS roomserver_state_snapshots (
+			state_snapshot_nid bigint PRIMARY KEY DEFAULT nextval('roomserver_state_snapshot_nid_seq'),
+			room_nid bigint NOT NULL,
+			state_block_nids bigint[] NOT NULL,
+			UNIQUE (room_nid, state_block_nids)
+		);
+	`)
+	if err != nil {
+		return fmt.Errorf("tx.Exec: %w", err)
+	}
+	snapshotrows, err := tx.Query(`SELECT state_snapshot_nid, room_nid, state_block_nids FROM _roomserver_state_snapshots;`)
+	if err != nil {
+		return fmt.Errorf("tx.Query: %w", err)
+	}
+	defer internal.CloseAndLogIfError(context.TODO(), snapshotrows, "rows.close() failed")
+	for snapshotrows.Next() {
+		var snapshot types.StateSnapshotNID
+		var room types.RoomNID
+		var blocks []types.StateBlockNID
+		if err = snapshotrows.Scan(&snapshot, &room, &blocks); err != nil {
+			return fmt.Errorf("rows.Scan: %w", err)
+		}
+
+		var newblocks []types.StateBlockNID
+		for _, block := range blocks {
+			if err = func() error {
+				blockrows, berr := tx.Query(`SELECT event_nid FROM _roomserver_state_block WHERE state_block_nid = $1`, block)
+				if berr != nil {
+					return fmt.Errorf("tx.Query (event nids from old block): %w", berr)
+				}
+				defer internal.CloseAndLogIfError(context.TODO(), blockrows, "rows.close() failed")
+				events := types.EventNIDs{}
+				for blockrows.Next() {
+					var event types.EventNID
+					if err = blockrows.Scan(&event); err != nil {
+						return fmt.Errorf("rows.Scan: %w", err)
+					}
+					events = append(events, event)
+				}
+				events = events[:util.SortAndUnique(events)]
+
+				var blocknid types.StateBlockNID
+				err = tx.QueryRow(`
+					INSERT INTO roomserver_state_block (event_nids)
+						VALUES ($1)
+						ON CONFLICT (event_nids) DO UPDATE SET event_nids=$1
+						RETURNING state_block_nid
+				`, events).Scan(&blocknid)
+				if err != nil {
+					return fmt.Errorf("tx.QueryRow.Scan (insert new block): %w", err)
+				}
+				newblocks = append(newblocks, blocknid)
+				return nil
+			}(); err != nil {
+				return err
+			}
+
+			var newsnapshot types.StateSnapshotNID
+			err = tx.QueryRow(`
+				INSERT INTO roomserver_state_snapshots (room_nid, state_block_nids)
+					VALUES ($1, $2)
+					ON CONFLICT (room_nid, state_block_nids) DO UPDATE SET room_nid=$3
+					RETURNING state_snapshot_nid
+			`, room, newblocks, room).Scan(&newsnapshot)
+			if err != nil {
+				return fmt.Errorf("tx.QueryRow.Scan (insert new snapshot): %w", err)
+			}
+
+			_, err = tx.Exec(`UPDATE roomserver_events SET state_snapshot_nid=$1 WHERE state_snapshot_nid=$2`, newsnapshot, snapshot)
+			if err != nil {
+				return fmt.Errorf("tx.Exec (update events): %w", err)
+			}
+			_, err = tx.Exec(`UPDATE roomserver_rooms SET state_snapshot_nid=$1 WHERE state_snapshot_nid=$2`, newsnapshot, snapshot)
+			if err != nil {
+				return fmt.Errorf("tx.Exec (update rooms): %w", err)
+			}
+
+			fmt.Println("Rewrote snapshot", snapshot, "to", newsnapshot)
+		}
+	}
+
+	if _, err = tx.Exec(`DROP TABLE _roomserver_state_snapshots;`); err != nil {
+		return fmt.Errorf("tx.Exec (delete old snapshot table): %w", err)
+	}
+	if _, err = tx.Exec(`DROP TABLE _roomserver_state_block;`); err != nil {
+		return fmt.Errorf("tx.Exec (delete old block table): %w", err)
+	}
+
+	return nil
+}
+
+func DownStateBlocksRefactor(tx *sql.Tx) error {
+	panic("DOWN!")
+}