Add migrations and refactor internal structs

2025-03-10 13:37:11 +00:00 · 2024-05-17 13:45:14 +01:00 · 2024-05-17 13:45:14 +01:00 · b383ed0d82
commit b383ed0d82
parent 2cd9a81ab2
12 changed files with 445 additions and 223 deletions
--- a/internal/device_data.go
+++ b/internal/device_data.go
@ -1,9 +1,5 @@
 package internal

-import (
-	"sync"
-)
-
 const (
 	bitOTKCount int = iota
 	bitFallbackKeyTypes
@ -18,9 +14,22 @@ func isBitSet(n int, bit int) bool {
 	return val > 0
 }

-// DeviceData contains useful data for this user's device. This list can be expanded without prompting
-// schema changes. These values are upserted into the database and persisted forever.
+// DeviceData contains useful data for this user's device.
 type DeviceData struct {
+	DeviceListChanges
+	DeviceKeyData
+	UserID   string
+	DeviceID string
+}
+
+// This is calculated from device_lists table
+type DeviceListChanges struct {
+	DeviceListChanged []string
+	DeviceListLeft    []string
+}
+
+// This gets serialised as CBOR in device_data table
+type DeviceKeyData struct {
 	// Contains the latest device_one_time_keys_count values.
 	// Set whenever this field arrives down the v2 poller, and it replaces what was previously there.
 	OTKCounts MapStringInt `json:"otk"`
@ -28,95 +37,22 @@ type DeviceData struct {
 	// Set whenever this field arrives down the v2 poller, and it replaces what was previously there.
 	// If this is a nil slice this means no change. If this is an empty slice then this means the fallback key was used up.
 	FallbackKeyTypes []string `json:"fallback"`
-
-	DeviceLists DeviceLists `json:"dl"`
-
 	// bitset for which device data changes are present. They accumulate until they get swapped over
 	// when they get reset
 	ChangedBits int `json:"c"`
-
-	UserID   string
-	DeviceID string
 }

-func (dd *DeviceData) SetOTKCountChanged() {
+func (dd *DeviceKeyData) SetOTKCountChanged() {
 	dd.ChangedBits = setBit(dd.ChangedBits, bitOTKCount)
 }

-func (dd *DeviceData) SetFallbackKeysChanged() {
+func (dd *DeviceKeyData) SetFallbackKeysChanged() {
 	dd.ChangedBits = setBit(dd.ChangedBits, bitFallbackKeyTypes)
 }

-func (dd *DeviceData) OTKCountChanged() bool {
+func (dd *DeviceKeyData) OTKCountChanged() bool {
 	return isBitSet(dd.ChangedBits, bitOTKCount)
 }
-func (dd *DeviceData) FallbackKeysChanged() bool {
+func (dd *DeviceKeyData) FallbackKeysChanged() bool {
 	return isBitSet(dd.ChangedBits, bitFallbackKeyTypes)
 }
-
-type UserDeviceKey struct {
-	UserID   string
-	DeviceID string
-}
-
-type DeviceDataMap struct {
-	deviceDataMu  *sync.Mutex
-	deviceDataMap map[UserDeviceKey]*DeviceData
-	Pos           int64
-}
-
-func NewDeviceDataMap(startPos int64, devices []DeviceData) *DeviceDataMap {
-	ddm := &DeviceDataMap{
-		deviceDataMu:  &sync.Mutex{},
-		deviceDataMap: make(map[UserDeviceKey]*DeviceData),
-		Pos:           startPos,
-	}
-	for i, dd := range devices {
-		ddm.deviceDataMap[UserDeviceKey{
-			UserID:   dd.UserID,
-			DeviceID: dd.DeviceID,
-		}] = &devices[i]
-	}
-	return ddm
-}
-
-func (d *DeviceDataMap) Get(userID, deviceID string) *DeviceData {
-	key := UserDeviceKey{
-		UserID:   userID,
-		DeviceID: deviceID,
-	}
-	d.deviceDataMu.Lock()
-	defer d.deviceDataMu.Unlock()
-	dd, ok := d.deviceDataMap[key]
-	if !ok {
-		return nil
-	}
-	return dd
-}
-
-func (d *DeviceDataMap) Update(dd DeviceData) DeviceData {
-	key := UserDeviceKey{
-		UserID:   dd.UserID,
-		DeviceID: dd.DeviceID,
-	}
-	d.deviceDataMu.Lock()
-	defer d.deviceDataMu.Unlock()
-	existing, ok := d.deviceDataMap[key]
-	if !ok {
-		existing = &DeviceData{
-			UserID:   dd.UserID,
-			DeviceID: dd.DeviceID,
-		}
-	}
-	if dd.OTKCounts != nil {
-		existing.OTKCounts = dd.OTKCounts
-	}
-	if dd.FallbackKeyTypes != nil {
-		existing.FallbackKeyTypes = dd.FallbackKeyTypes
-	}
-	existing.DeviceLists = existing.DeviceLists.Combine(dd.DeviceLists)
-
-	d.deviceDataMap[key] = existing
-
-	return *existing
-}
--- a/state/device_data_table.go
+++ b/state/device_data_table.go
@ -15,9 +15,9 @@ type DeviceDataRow struct {
 	ID       int64  `db:"id"`
 	UserID   string `db:"user_id"`
 	DeviceID string `db:"device_id"`
-	// This will contain internal.DeviceData serialised as JSON. It's stored in a single column as we don't
+	// This will contain internal.DeviceKeyData serialised as JSON. It's stored in a single column as we don't
 	// need to perform searches on this data.
-	Data []byte `db:"data"`
+	KeyData []byte `db:"data"`
 }

 type DeviceDataTable struct {
@ -47,6 +47,7 @@ func NewDeviceDataTable(db *sqlx.DB) *DeviceDataTable {
 // This should only be called by the v3 HTTP APIs when servicing an E2EE extension request.
 func (t *DeviceDataTable) Select(userID, deviceID string, swap bool) (result *internal.DeviceData, err error) {
 	err = sqlutil.WithTransaction(t.db, func(txn *sqlx.Tx) error {
+		// grab otk counts and fallback key types
 		var row DeviceDataRow
 		err = txn.Get(&row, `SELECT data FROM syncv3_device_data WHERE user_id=$1 AND device_id=$2 FOR UPDATE`, userID, deviceID)
 		if err != nil {
@ -56,32 +57,38 @@ func (t *DeviceDataTable) Select(userID, deviceID string, swap bool) (result *in
 			}
 			return err
 		}
+		result = &internal.DeviceData{}
+		var keyData *internal.DeviceKeyData
 		// unmarshal to swap
-		opts := cbor.DecOptions{
-			MaxMapPairs: 1000000000, // 1 billion :(
-		}
-		decMode, err := opts.DecMode()
-		if err != nil {
-			return err
-		}
-		if err = decMode.Unmarshal(row.Data, &result); err != nil {
+		if err = cbor.Unmarshal(row.KeyData, &keyData); err != nil {
 			return err
 		}
 		result.UserID = userID
 		result.DeviceID = deviceID
+		if keyData != nil {
+			result.DeviceKeyData = *keyData
+		}
+
+		deviceListChanges, err := t.deviceListTable.SelectTx(txn, userID, deviceID, swap)
+		if err != nil {
+			return err
+		}
+		for targetUserID, targetState := range deviceListChanges {
+			switch targetState {
+			case internal.DeviceListChanged:
+				result.DeviceListChanged = append(result.DeviceListChanged, targetUserID)
+			case internal.DeviceListLeft:
+				result.DeviceListLeft = append(result.DeviceListLeft, targetUserID)
+			}
+		}
 		if !swap {
 			return nil // don't swap
 		}
-		// the caller will only look at sent, so make sure what is new is now in sent
-		result.DeviceLists.Sent = result.DeviceLists.New
-
 		// swap over the fields
-		writeBack := *result
-		writeBack.DeviceLists.Sent = result.DeviceLists.New
-		writeBack.DeviceLists.New = make(map[string]int)
+		writeBack := *keyData
 		writeBack.ChangedBits = 0

-		if reflect.DeepEqual(result, &writeBack) {
+		if reflect.DeepEqual(keyData, &writeBack) {
 			// The update to the DB would be a no-op; don't bother with it.
 			// This helps reduce write usage and the contention on the unique index for
 			// the device_data table.
@ -99,14 +106,13 @@ func (t *DeviceDataTable) Select(userID, deviceID string, swap bool) (result *in
 	return
 }

-func (t *DeviceDataTable) DeleteDevice(userID, deviceID string) error {
-	_, err := t.db.Exec(`DELETE FROM syncv3_device_data WHERE user_id = $1 AND device_id = $2`, userID, deviceID)
-	return err
-}
-
 // Upsert combines what is in the database for this user|device with the partial entry `dd`
-func (t *DeviceDataTable) Upsert(dd *internal.DeviceData) (err error) {
+func (t *DeviceDataTable) Upsert(dd *internal.DeviceData, deviceListChanges map[string]int) (err error) {
 	err = sqlutil.WithTransaction(t.db, func(txn *sqlx.Tx) error {
+		// Update device lists
+		if err = t.deviceListTable.UpsertTx(txn, dd.UserID, dd.DeviceID, deviceListChanges); err != nil {
+			return err
+		}
 		// select what already exists
 		var row DeviceDataRow
 		err = txn.Get(&row, `SELECT data FROM syncv3_device_data WHERE user_id=$1 AND device_id=$2 FOR UPDATE`, dd.UserID, dd.DeviceID)
@ -114,30 +120,22 @@ func (t *DeviceDataTable) Upsert(dd *internal.DeviceData) (err error) {
 			return err
 		}
 		// unmarshal and combine
-		var tempDD internal.DeviceData
-		if len(row.Data) > 0 {
-			opts := cbor.DecOptions{
-				MaxMapPairs: 1000000000, // 1 billion :(
-			}
-			decMode, err := opts.DecMode()
-			if err != nil {
-				return err
-			}
-			if err = decMode.Unmarshal(row.Data, &tempDD); err != nil {
+		var keyData internal.DeviceKeyData
+		if len(row.KeyData) > 0 {
+			if err = cbor.Unmarshal(row.KeyData, &keyData); err != nil {
 				return err
 			}
 		}
 		if dd.FallbackKeyTypes != nil {
-			tempDD.FallbackKeyTypes = dd.FallbackKeyTypes
-			tempDD.SetFallbackKeysChanged()
+			keyData.FallbackKeyTypes = dd.FallbackKeyTypes
+			keyData.SetFallbackKeysChanged()
 		}
 		if dd.OTKCounts != nil {
-			tempDD.OTKCounts = dd.OTKCounts
-			tempDD.SetOTKCountChanged()
+			keyData.OTKCounts = dd.OTKCounts
+			keyData.SetOTKCountChanged()
 		}
-		tempDD.DeviceLists = tempDD.DeviceLists.Combine(dd.DeviceLists)

-		data, err := cbor.Marshal(tempDD)
+		data, err := cbor.Marshal(keyData)
 		if err != nil {
 			return err
 		}
--- a/state/device_data_table_test.go
+++ b/state/device_data_table_test.go
@ -22,9 +22,6 @@ func assertDeviceData(t *testing.T, g, w internal.DeviceData) {
 	assertVal(t, "FallbackKeyTypes", g.FallbackKeyTypes, w.FallbackKeyTypes)
 	assertVal(t, "OTKCounts", g.OTKCounts, w.OTKCounts)
 	assertVal(t, "ChangedBits", g.ChangedBits, w.ChangedBits)
-	if w.DeviceLists.Sent != nil {
-		assertVal(t, "DeviceLists.Sent", g.DeviceLists.Sent, w.DeviceLists.Sent)
-	}
 }

 // Tests OTKCounts and FallbackKeyTypes behaviour
@ -40,21 +37,27 @@ func TestDeviceDataTableOTKCountAndFallbackKeyTypes(t *testing.T) {
 		{
 			UserID:   userID,
 			DeviceID: deviceID,
-			OTKCounts: map[string]int{
-				"foo": 100,
-				"bar": 92,
+			DeviceKeyData: internal.DeviceKeyData{
+				OTKCounts: map[string]int{
+					"foo": 100,
+					"bar": 92,
+				},
 			},
 		},
-		{
-			UserID:           userID,
-			DeviceID:         deviceID,
-			FallbackKeyTypes: []string{"foobar"},
-		},
 		{
 			UserID:   userID,
 			DeviceID: deviceID,
-			OTKCounts: map[string]int{
-				"foo": 99,
+			DeviceKeyData: internal.DeviceKeyData{
+				FallbackKeyTypes: []string{"foobar"},
+			},
+		},
+		{
+			UserID:   userID,
+			DeviceID: deviceID,
+			DeviceKeyData: internal.DeviceKeyData{
+				OTKCounts: map[string]int{
+					"foo": 99,
+				},
 			},
 		},
 		{
@ -65,7 +68,7 @@ func TestDeviceDataTableOTKCountAndFallbackKeyTypes(t *testing.T) {

 	// apply them
 	for _, dd := range deltas {
-		err := table.Upsert(&dd)
+		err := table.Upsert(&dd, nil)
 		assertNoError(t, err)
 	}

@ -79,10 +82,12 @@ func TestDeviceDataTableOTKCountAndFallbackKeyTypes(t *testing.T) {
 		want := internal.DeviceData{
 			UserID:   userID,
 			DeviceID: deviceID,
-			OTKCounts: map[string]int{
-				"foo": 99,
+			DeviceKeyData: internal.DeviceKeyData{
+				OTKCounts: map[string]int{
+					"foo": 99,
+				},
+				FallbackKeyTypes: []string{"foobar"},
 			},
-			FallbackKeyTypes: []string{"foobar"},
 		}
 		want.SetFallbackKeysChanged()
 		want.SetOTKCountChanged()
@ -95,10 +100,12 @@ func TestDeviceDataTableOTKCountAndFallbackKeyTypes(t *testing.T) {
 	want := internal.DeviceData{
 		UserID:   userID,
 		DeviceID: deviceID,
-		OTKCounts: map[string]int{
-			"foo": 99,
+		DeviceKeyData: internal.DeviceKeyData{
+			OTKCounts: map[string]int{
+				"foo": 99,
+			},
+			FallbackKeyTypes: []string{"foobar"},
 		},
-		FallbackKeyTypes: []string{"foobar"},
 	}
 	want.SetFallbackKeysChanged()
 	want.SetOTKCountChanged()
@ -110,10 +117,12 @@ func TestDeviceDataTableOTKCountAndFallbackKeyTypes(t *testing.T) {
 	want = internal.DeviceData{
 		UserID:   userID,
 		DeviceID: deviceID,
-		OTKCounts: map[string]int{
-			"foo": 99,
+		DeviceKeyData: internal.DeviceKeyData{
+			OTKCounts: map[string]int{
+				"foo": 99,
+			},
+			FallbackKeyTypes: []string{"foobar"},
 		},
-		FallbackKeyTypes: []string{"foobar"},
 	}
 	assertDeviceData(t, *got, want)
 }
@ -127,29 +136,32 @@ func TestDeviceDataTableBitset(t *testing.T) {
 	otkUpdate := internal.DeviceData{
 		UserID:   userID,
 		DeviceID: deviceID,
-		OTKCounts: map[string]int{
-			"foo": 100,
-			"bar": 92,
+		DeviceKeyData: internal.DeviceKeyData{
+			OTKCounts: map[string]int{
+				"foo": 100,
+				"bar": 92,
+			},
 		},
-		DeviceLists: internal.DeviceLists{New: map[string]int{}, Sent: map[string]int{}},
 	}
 	fallbakKeyUpdate := internal.DeviceData{
-		UserID:           userID,
-		DeviceID:         deviceID,
-		FallbackKeyTypes: []string{"foo", "bar"},
-		DeviceLists:      internal.DeviceLists{New: map[string]int{}, Sent: map[string]int{}},
+		UserID:   userID,
+		DeviceID: deviceID,
+		DeviceKeyData: internal.DeviceKeyData{
+			FallbackKeyTypes: []string{"foo", "bar"},
+		},
 	}
 	bothUpdate := internal.DeviceData{
-		UserID:           userID,
-		DeviceID:         deviceID,
-		FallbackKeyTypes: []string{"both"},
-		OTKCounts: map[string]int{
-			"both": 100,
+		UserID:   userID,
+		DeviceID: deviceID,
+		DeviceKeyData: internal.DeviceKeyData{
+			FallbackKeyTypes: []string{"both"},
+			OTKCounts: map[string]int{
+				"both": 100,
+			},
 		},
-		DeviceLists: internal.DeviceLists{New: map[string]int{}, Sent: map[string]int{}},
 	}

-	err := table.Upsert(&otkUpdate)
+	err := table.Upsert(&otkUpdate, nil)
 	assertNoError(t, err)
 	got, err := table.Select(userID, deviceID, true)
 	assertNoError(t, err)
@ -161,7 +173,7 @@ func TestDeviceDataTableBitset(t *testing.T) {
 	otkUpdate.ChangedBits = 0
 	assertDeviceData(t, *got, otkUpdate)
 	// now same for fallback keys, but we won't swap them so it should return those diffs
-	err = table.Upsert(&fallbakKeyUpdate)
+	err = table.Upsert(&fallbakKeyUpdate, nil)
 	assertNoError(t, err)
 	fallbakKeyUpdate.OTKCounts = otkUpdate.OTKCounts
 	got, err = table.Select(userID, deviceID, false)
@ -173,7 +185,7 @@ func TestDeviceDataTableBitset(t *testing.T) {
 	fallbakKeyUpdate.SetFallbackKeysChanged()
 	assertDeviceData(t, *got, fallbakKeyUpdate)
 	// updating both works
-	err = table.Upsert(&bothUpdate)
+	err = table.Upsert(&bothUpdate, nil)
 	assertNoError(t, err)
 	got, err = table.Select(userID, deviceID, true)
 	assertNoError(t, err)
--- a/state/device_list_table.go
+++ b/state/device_list_table.go
@ -14,6 +14,14 @@ const (
 	BucketSent = 2
 )

+type DeviceListRow struct {
+	UserID       string `db:"user_id"`
+	DeviceID     string `db:"device_id"`
+	TargetUserID string `db:"target_user_id"`
+	TargetState  int    `db:"target_state"`
+	Bucket       int    `db:"bucket"`
+}
+
 type DeviceListTable struct {
 	db *sqlx.DB
 }
@ -39,24 +47,9 @@ func NewDeviceListTable(db *sqlx.DB) *DeviceListTable {
 	}
 }

-// Upsert new device list changes.
 func (t *DeviceListTable) Upsert(userID, deviceID string, deviceListChanges map[string]int) (err error) {
 	err = sqlutil.WithTransaction(t.db, func(txn *sqlx.Tx) error {
-		for targetUserID, targetState := range deviceListChanges {
-			if targetState != internal.DeviceListChanged && targetState != internal.DeviceListLeft {
-				sentry.CaptureException(fmt.Errorf("DeviceListTable.Upsert invalid target_state: %d this is a programming error", targetState))
-				continue
-			}
-			_, err = txn.Exec(
-				`INSERT INTO syncv3_device_list_updates(user_id, device_id, target_user_id, target_state, bucket) VALUES($1,$2,$3,$4,$5)
-			ON CONFLICT (user_id, device_id, target_user_id, bucket) DO UPDATE SET target_state=$4`,
-				userID, deviceID, targetUserID, targetState, BucketNew,
-			)
-			if err != nil {
-				return err
-			}
-		}
-		return nil
+		return t.UpsertTx(txn, userID, deviceID, deviceListChanges)
 	})
 	if err != nil {
 		sentry.CaptureException(err)
@ -64,33 +57,70 @@ func (t *DeviceListTable) Upsert(userID, deviceID string, deviceListChanges map[
 	return
 }

-// Select device list changes for this client. Returns a map of user_id => change enum.
+// Upsert new device list changes.
+func (t *DeviceListTable) UpsertTx(txn *sqlx.Tx, userID, deviceID string, deviceListChanges map[string]int) (err error) {
+	if len(deviceListChanges) == 0 {
+		return nil
+	}
+	var deviceListRows []DeviceListRow
+	for targetUserID, targetState := range deviceListChanges {
+		if targetState != internal.DeviceListChanged && targetState != internal.DeviceListLeft {
+			sentry.CaptureException(fmt.Errorf("DeviceListTable.Upsert invalid target_state: %d this is a programming error", targetState))
+			continue
+		}
+		deviceListRows = append(deviceListRows, DeviceListRow{
+			UserID:       userID,
+			DeviceID:     deviceID,
+			TargetUserID: targetUserID,
+			TargetState:  targetState,
+			Bucket:       BucketNew,
+		})
+	}
+	chunks := sqlutil.Chunkify(5, MaxPostgresParameters, DeviceListChunker(deviceListRows))
+	for _, chunk := range chunks {
+		_, err := txn.NamedExec(`
+						INSERT INTO syncv3_device_list_updates(user_id, device_id, target_user_id, target_state, bucket)
+						VALUES(:user_id, :device_id, :target_user_id, :target_state, :bucket)
+						ON CONFLICT (user_id, device_id, target_user_id, bucket) DO UPDATE SET target_state = EXCLUDED.target_state`, chunk)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+	return
+}
+
 func (t *DeviceListTable) Select(userID, deviceID string, swap bool) (result internal.MapStringInt, err error) {
 	err = sqlutil.WithTransaction(t.db, func(txn *sqlx.Tx) error {
-		if !swap {
-			// read only view, just return what we previously sent and don't do anything else.
-			result, err = t.selectDeviceListChangesInBucket(txn, userID, deviceID, BucketSent)
-			return err
-		}
-
-		// delete the now acknowledged 'sent' data
-		_, err = txn.Exec(`DELETE FROM syncv3_device_list_updates WHERE user_id=$1 AND device_id=$2 AND bucket=$3`, userID, deviceID, BucketSent)
-		if err != nil {
-			return err
-		}
-		// grab any 'new' updates
-		result, err = t.selectDeviceListChangesInBucket(txn, userID, deviceID, BucketNew)
-		if err != nil {
-			return err
-		}
-
-		// mark these 'new' updates as 'sent'
-		_, err = txn.Exec(`UPDATE syncv3_device_list_updates SET bucket=$1 WHERE user_id=$2 AND device_id=$3 AND bucket=$4`, BucketSent, userID, deviceID, BucketNew)
+		result, err = t.SelectTx(txn, userID, deviceID, swap)
 		return err
 	})
 	return
 }

+// Select device list changes for this client. Returns a map of user_id => change enum.
+func (t *DeviceListTable) SelectTx(txn *sqlx.Tx, userID, deviceID string, swap bool) (result internal.MapStringInt, err error) {
+	if !swap {
+		// read only view, just return what we previously sent and don't do anything else.
+		return t.selectDeviceListChangesInBucket(txn, userID, deviceID, BucketSent)
+	}
+
+	// delete the now acknowledged 'sent' data
+	_, err = txn.Exec(`DELETE FROM syncv3_device_list_updates WHERE user_id=$1 AND device_id=$2 AND bucket=$3`, userID, deviceID, BucketSent)
+	if err != nil {
+		return nil, err
+	}
+	// grab any 'new' updates
+	result, err = t.selectDeviceListChangesInBucket(txn, userID, deviceID, BucketNew)
+	if err != nil {
+		return nil, err
+	}
+
+	// mark these 'new' updates as 'sent'
+	_, err = txn.Exec(`UPDATE syncv3_device_list_updates SET bucket=$1 WHERE user_id=$2 AND device_id=$3 AND bucket=$4`, BucketSent, userID, deviceID, BucketNew)
+	return result, err
+}
+
 func (t *DeviceListTable) selectDeviceListChangesInBucket(txn *sqlx.Tx, userID, deviceID string, bucket int) (result internal.MapStringInt, err error) {
 	rows, err := txn.Query(`SELECT target_user_id, target_state FROM syncv3_device_list_updates WHERE user_id=$1 AND device_id=$2 AND bucket=$3`, userID, deviceID, bucket)
 	if err != nil {
@ -108,3 +138,12 @@ func (t *DeviceListTable) selectDeviceListChangesInBucket(txn *sqlx.Tx, userID,
 	}
 	return result, rows.Err()
 }
+
+type DeviceListChunker []DeviceListRow
+
+func (c DeviceListChunker) Len() int {
+	return len(c)
+}
+func (c DeviceListChunker) Subslice(i, j int) sqlutil.Chunker {
+	return c[i:j]
+}
--- a/state/device_list_table_test.go
+++ b/state/device_list_table_test.go
@ -1,6 +1,7 @@
 package state

 import (
+	"fmt"
 	"testing"

 	"github.com/matrix-org/sliding-sync/internal"
@ -105,4 +106,15 @@ func TestDeviceListTable(t *testing.T) {
 	got, err = table.Select(userID, deviceID, true)
 	assertNoError(t, err)
 	assertVal(t, "swap select did not return combined new items", got, internal.MapStringInt{})
+
+	// large updates work (chunker)
+	largeUpdate := internal.MapStringInt{}
+	for i := 0; i < 100000; i++ {
+		largeUpdate[fmt.Sprintf("user_%d", i)] = internal.DeviceListChanged
+	}
+	err = table.Upsert(userID, deviceID, largeUpdate)
+	assertNoError(t, err)
+	got, err = table.Select(userID, deviceID, true)
+	assertNoError(t, err)
+	assertVal(t, "swap select did not return large items", got, largeUpdate)
 }
--- a/state/migrations/20230802121023_device_data_jsonb_test.go
+++ b/state/migrations/20230802121023_device_data_jsonb_test.go
@ -7,7 +7,6 @@ import (

 	"github.com/jmoiron/sqlx"
 	_ "github.com/lib/pq"
-	"github.com/matrix-org/sliding-sync/internal"
 	"github.com/matrix-org/sliding-sync/testutils"
 )

@ -48,8 +47,8 @@ func TestJSONBMigration(t *testing.T) {
 	defer tx.Commit()

 	// insert some "invalid" data
-	dd := internal.DeviceData{
-		DeviceLists: internal.DeviceLists{
+	dd := OldDeviceData{
+		DeviceLists: OldDeviceLists{
 			New:  map[string]int{"@💣:localhost": 1},
 			Sent: map[string]int{},
 		},
--- a/state/migrations/20230814183302_cbor_device_data.go
+++ b/state/migrations/20230814183302_cbor_device_data.go
@ -9,7 +9,6 @@ import (
 	"strings"

 	"github.com/fxamacker/cbor/v2"
-	"github.com/matrix-org/sliding-sync/internal"
 	"github.com/matrix-org/sliding-sync/sync2"
 	"github.com/pressly/goose/v3"
 )
@ -59,7 +58,7 @@ func upCborDeviceData(ctx context.Context, tx *sql.Tx) error {
 	}

 	for dd, jsonBytes := range deviceDatas {
-		var data internal.DeviceData
+		var data OldDeviceData
 		if err := json.Unmarshal(jsonBytes, &data); err != nil {
 			return fmt.Errorf("failed to unmarshal JSON: %v -> %v", string(jsonBytes), err)
 		}
@ -115,7 +114,7 @@ func downCborDeviceData(ctx context.Context, tx *sql.Tx) error {
 	}

 	for dd, cborBytes := range deviceDatas {
-		var data internal.DeviceData
+		var data OldDeviceData
 		if err := cbor.Unmarshal(cborBytes, &data); err != nil {
 			return fmt.Errorf("failed to unmarshal CBOR: %v", err)
 		}
--- a/state/migrations/20230814183302_cbor_device_data_test.go
+++ b/state/migrations/20230814183302_cbor_device_data_test.go
@ -2,13 +2,15 @@ package migrations

 import (
 	"context"
+	"database/sql"
 	"encoding/json"
 	"reflect"
 	"testing"

+	"github.com/fxamacker/cbor/v2"
+	"github.com/jmoiron/sqlx"
 	_ "github.com/lib/pq"
-	"github.com/matrix-org/sliding-sync/internal"
-	"github.com/matrix-org/sliding-sync/state"
+	"github.com/matrix-org/sliding-sync/sqlutil"
 )

 func TestCBORBMigration(t *testing.T) {
@ -30,9 +32,9 @@ func TestCBORBMigration(t *testing.T) {
 		t.Fatal(err)
 	}

-	rowData := []internal.DeviceData{
+	rowData := []OldDeviceData{
 		{
-			DeviceLists: internal.DeviceLists{
+			DeviceLists: OldDeviceLists{
 				New:  map[string]int{"@bob:localhost": 2},
 				Sent: map[string]int{},
 			},
@ -43,7 +45,7 @@ func TestCBORBMigration(t *testing.T) {
 			UserID:           "@alice:localhost",
 		},
 		{
-			DeviceLists: internal.DeviceLists{
+			DeviceLists: OldDeviceLists{
 				New:  map[string]int{"@💣:localhost": 1, "@bomb:localhost": 2},
 				Sent: map[string]int{"@sent:localhost": 1},
 			},
@ -78,9 +80,8 @@ func TestCBORBMigration(t *testing.T) {
 	tx.Commit()

 	// ensure we can now select it
-	table := state.NewDeviceDataTable(db)
 	for _, want := range rowData {
-		got, err := table.Select(want.UserID, want.DeviceID, false)
+		got, err := OldDeviceDataTableSelect(db, want.UserID, want.DeviceID, false)
 		if err != nil {
 			t.Fatal(err)
 		}
@ -101,7 +102,7 @@ func TestCBORBMigration(t *testing.T) {

 	// ensure it is what we originally inserted
 	for _, want := range rowData {
-		var got internal.DeviceData
+		var got OldDeviceData
 		var gotBytes []byte
 		err = tx.QueryRow(`SELECT data FROM syncv3_device_data WHERE user_id=$1 AND device_id=$2`, want.UserID, want.DeviceID).Scan(&gotBytes)
 		if err != nil {
@ -119,3 +120,66 @@ func TestCBORBMigration(t *testing.T) {

 	tx.Commit()
 }
+
+type OldDeviceDataRow struct {
+	ID       int64  `db:"id"`
+	UserID   string `db:"user_id"`
+	DeviceID string `db:"device_id"`
+	// This will contain internal.DeviceData serialised as JSON. It's stored in a single column as we don't
+	// need to perform searches on this data.
+	Data []byte `db:"data"`
+}
+
+func OldDeviceDataTableSelect(db *sqlx.DB, userID, deviceID string, swap bool) (result *OldDeviceData, err error) {
+	err = sqlutil.WithTransaction(db, func(txn *sqlx.Tx) error {
+		var row OldDeviceDataRow
+		err = txn.Get(&row, `SELECT data FROM syncv3_device_data WHERE user_id=$1 AND device_id=$2 FOR UPDATE`, userID, deviceID)
+		if err != nil {
+			if err == sql.ErrNoRows {
+				// if there is no device data for this user, it's not an error.
+				return nil
+			}
+			return err
+		}
+		// unmarshal to swap
+		opts := cbor.DecOptions{
+			MaxMapPairs: 1000000000, // 1 billion :(
+		}
+		decMode, err := opts.DecMode()
+		if err != nil {
+			return err
+		}
+		if err = decMode.Unmarshal(row.Data, &result); err != nil {
+			return err
+		}
+		result.UserID = userID
+		result.DeviceID = deviceID
+		if !swap {
+			return nil // don't swap
+		}
+		// the caller will only look at sent, so make sure what is new is now in sent
+		result.DeviceLists.Sent = result.DeviceLists.New
+
+		// swap over the fields
+		writeBack := *result
+		writeBack.DeviceLists.Sent = result.DeviceLists.New
+		writeBack.DeviceLists.New = make(map[string]int)
+		writeBack.ChangedBits = 0
+
+		if reflect.DeepEqual(result, &writeBack) {
+			// The update to the DB would be a no-op; don't bother with it.
+			// This helps reduce write usage and the contention on the unique index for
+			// the device_data table.
+			return nil
+		}
+		// re-marshal and write
+		data, err := cbor.Marshal(writeBack)
+		if err != nil {
+			return err
+		}
+
+		_, err = txn.Exec(`UPDATE syncv3_device_data SET data=$1 WHERE user_id=$2 AND device_id=$3`, data, userID, deviceID)
+		return err
+	})
+	return
+}
--- a/state/migrations/20240517104423_device_list_table.go
+++ b/state/migrations/20240517104423_device_list_table.go
@ -0,0 +1,158 @@
+package migrations
+
+import (
+	"context"
+	"database/sql"
+	"time"
+
+	"github.com/fxamacker/cbor/v2"
+	"github.com/lib/pq"
+	"github.com/matrix-org/sliding-sync/internal"
+	"github.com/matrix-org/sliding-sync/state"
+	"github.com/pressly/goose/v3"
+)
+
+type OldDeviceData struct {
+	// Contains the latest device_one_time_keys_count values.
+	// Set whenever this field arrives down the v2 poller, and it replaces what was previously there.
+	OTKCounts internal.MapStringInt `json:"otk"`
+	// Contains the latest device_unused_fallback_key_types value
+	// Set whenever this field arrives down the v2 poller, and it replaces what was previously there.
+	// If this is a nil slice this means no change. If this is an empty slice then this means the fallback key was used up.
+	FallbackKeyTypes []string `json:"fallback"`
+
+	DeviceLists OldDeviceLists `json:"dl"`
+
+	// bitset for which device data changes are present. They accumulate until they get swapped over
+	// when they get reset
+	ChangedBits int `json:"c"`
+
+	UserID   string
+	DeviceID string
+}
+
+type OldDeviceLists struct {
+	// map user_id -> DeviceList enum
+	New  internal.MapStringInt `json:"n"`
+	Sent internal.MapStringInt `json:"s"`
+}
+
+func init() {
+	goose.AddMigrationContext(upDeviceListTable, downDeviceListTable)
+}
+
+func upDeviceListTable(ctx context.Context, tx *sql.Tx) error {
+	// create the table. It's a bit gross we need to dupe the schema here, but this is the first migration to
+	// add a new table like this.
+	_, err := tx.Exec(`
+	CREATE TABLE IF NOT EXISTS syncv3_device_list_updates (
+		user_id TEXT NOT NULL,
+		device_id TEXT NOT NULL,
+		target_user_id TEXT NOT NULL,
+		target_state SMALLINT NOT NULL,
+		bucket SMALLINT NOT NULL,
+		UNIQUE(user_id, device_id, target_user_id, bucket)
+	);
+	-- make an index so selecting all the rows is faster
+	CREATE INDEX IF NOT EXISTS syncv3_device_list_updates_bucket_idx ON syncv3_device_list_updates(user_id, device_id, bucket);
+	-- Set the fillfactor to 90%, to allow for HOT updates (e.g. we only
+	-- change the data, not anything indexed like the id)
+	ALTER TABLE syncv3_device_list_updates SET (fillfactor = 90);
+	`)
+	if err != nil {
+		return err
+	}
+
+	var count int
+	if err = tx.QueryRow(`SELECT count(*) FROM syncv3_device_data`).Scan(&count); err != nil {
+		return err
+	}
+	logger.Info().Int("count", count).Msg("transferring device list data for devices")
+
+	// scan for existing CBOR (streaming as the CBOR can be large) and for each row:
+	rows, err := tx.Query(`SELECT user_id, device_id, data FROM syncv3_device_data`)
+	if err != nil {
+		return err
+	}
+	defer rows.Close()
+	var userID string
+	var deviceID string
+	var data []byte
+	// every N seconds log an update
+	updateFrequency := time.Second * 2
+	lastUpdate := time.Now()
+	i := 0
+	for rows.Next() {
+		i++
+		if time.Since(lastUpdate) > updateFrequency {
+			logger.Info().Msgf("%d/%d process device list data", i, count)
+			lastUpdate = time.Now()
+		}
+		//  * deserialise the CBOR
+		if err := rows.Scan(&userID, &deviceID, &data); err != nil {
+			return err
+		}
+		result, err := deserialiseCBOR(data)
+		if err != nil {
+			return err
+		}
+
+		//  * transfer the device lists to the new device lists table
+		// uses a bulk copy that lib/pq supports
+		stmt, err := tx.Prepare(pq.CopyIn("syncv3_device_list_updates", "user_id", "device_id", "target_user_id", "target_state", "bucket"))
+		if err != nil {
+			return err
+		}
+		for targetUser, targetState := range result.DeviceLists.New {
+			if _, err := stmt.Exec(userID, deviceID, targetUser, targetState, state.BucketNew); err != nil {
+				return err
+			}
+		}
+		for targetUser, targetState := range result.DeviceLists.Sent {
+			if _, err := stmt.Exec(userID, deviceID, targetUser, targetState, state.BucketSent); err != nil {
+				return err
+			}
+		}
+		if _, err = stmt.Exec(); err != nil {
+			return err
+		}
+		if err = stmt.Close(); err != nil {
+			return err
+		}
+
+		//  * delete the device lists from the CBOR and update
+		result.DeviceLists = OldDeviceLists{
+			New:  make(internal.MapStringInt),
+			Sent: make(internal.MapStringInt),
+		}
+		data, err := cbor.Marshal(result)
+		if err != nil {
+			return err
+		}
+		_, err = tx.Exec(`UPDATE syncv3_device_data SET data=$1 WHERE user_id=$2 AND device_id=$3`, data, userID, deviceID)
+		if err != nil {
+			return err
+		}
+	}
+	return rows.Err()
+}
+
+func downDeviceListTable(ctx context.Context, tx *sql.Tx) error {
+	// no-op: we'll drop the device list updates but still work correctly as new/sent are still in the cbor but are empty
+	return nil
+}
+
+func deserialiseCBOR(data []byte) (*OldDeviceData, error) {
+	opts := cbor.DecOptions{
+		MaxMapPairs: 1000000000, // 1 billion :(
+	}
+	decMode, err := opts.DecMode()
+	if err != nil {
+		return nil, err
+	}
+	var result *OldDeviceData
+	if err = decMode.Unmarshal(data, &result); err != nil {
+		return nil, err
+	}
+	return result, nil
+}
--- a/state/migrations/20240517104423_device_list_table_test.go
+++ b/state/migrations/20240517104423_device_list_table_test.go
@ -0,0 +1,7 @@
+package migrations
+
+import "testing"
+
+func TestDeviceListTableMigration(t *testing.T) {
+
+}
--- a/sync2/handler2/handler.go
+++ b/sync2/handler2/handler.go
@ -234,15 +234,14 @@ func (h *Handler) OnE2EEData(ctx context.Context, userID, deviceID string, otkCo
 		defer wg.Done()
 		// some of these fields may be set
 		partialDD := internal.DeviceData{
-			UserID:           userID,
-			DeviceID:         deviceID,
-			OTKCounts:        otkCounts,
-			FallbackKeyTypes: fallbackKeyTypes,
-			DeviceLists: internal.DeviceLists{
-				New: deviceListChanges,
+			UserID:   userID,
+			DeviceID: deviceID,
+			DeviceKeyData: internal.DeviceKeyData{
+				OTKCounts:        otkCounts,
+				FallbackKeyTypes: fallbackKeyTypes,
 			},
 		}
-		err := h.Store.DeviceDataTable.Upsert(&partialDD)
+		err := h.Store.DeviceDataTable.Upsert(&partialDD, deviceListChanges)
 		if err != nil {
 			logger.Err(err).Str("user", userID).Msg("failed to upsert device data")
 			internal.GetSentryHubFromContextOrDefault(ctx).CaptureException(err)
--- a/sync3/extensions/e2ee.go
+++ b/sync3/extensions/e2ee.go
@ -70,11 +70,10 @@ func (r *E2EERequest) ProcessInitial(ctx context.Context, res *Response, extCtx
 		extRes.OTKCounts = dd.OTKCounts
 		hasUpdates = true
 	}
-	changed, left := internal.DeviceListChangesArrays(dd.DeviceLists.Sent)
-	if len(changed) > 0 || len(left) > 0 {
+	if len(dd.DeviceListChanged) > 0 || len(dd.DeviceListLeft) > 0 {
 		extRes.DeviceLists = &E2EEDeviceList{
-			Changed: changed,
-			Left:    left,
+			Changed: dd.DeviceListChanged,
+			Left:    dd.DeviceListLeft,
 		}
 		hasUpdates = true
 	}