diff --git a/mdb/collection.go b/mdb/collection.go
index 7e20015..73b035d 100644
--- a/mdb/collection.go
+++ b/mdb/collection.go
@@ -21,10 +21,10 @@ type Collection[T any] struct {
 	sanitize func(*T)
 	validate func(*T) error
 
-	indices       []Index[T]
-	uniqueIndices []Index[T]
+	indices       []*Index[T]
+	uniqueIndices []*Index[T]
 
-	ByID Index[T]
+	ByID *Index[T]
 
 	buf *bytes.Buffer
 }
@@ -65,8 +65,8 @@ func NewCollection[T any](db *Database, name string, conf *CollectionConfig[T])
 		copy:          conf.Copy,
 		sanitize:      conf.Sanitize,
 		validate:      conf.Validate,
-		indices:       []Index[T]{},
-		uniqueIndices: []Index[T]{},
+		indices:       []*Index[T]{},
+		uniqueIndices: []*Index[T]{},
 		buf:           &bytes.Buffer{},
 	}
 
@@ -92,7 +92,7 @@ func NewCollection[T any](db *Database, name string, conf *CollectionConfig[T])
 	return c
 }
 
-func (c Collection[T]) Name() string {
+func (c *Collection[T]) Name() string {
 	return c.name
 }
 
@@ -108,13 +108,13 @@ type indexConfig[T any] struct {
 	Include func(item *T) bool
 }
 
-func (c Collection[T]) Get(tx *Snapshot, id uint64) (*T, bool) {
+func (c *Collection[T]) Get(tx *Snapshot, id uint64) (*T, bool) {
 	x := new(T)
 	c.setID(x, id)
 	return c.ByID.Get(tx, x)
 }
 
-func (c Collection[T]) List(tx *Snapshot, ids []uint64, out []*T) []*T {
+func (c *Collection[T]) List(tx *Snapshot, ids []uint64, out []*T) []*T {
 	if len(ids) == 0 {
 		return out[:0]
 	}
@@ -135,8 +135,7 @@ func (c Collection[T]) List(tx *Snapshot, ids []uint64, out []*T) []*T {
 }
 
 // AddIndex: Add an index to the collection.
-func (c *Collection[T]) addIndex(conf indexConfig[T]) Index[T] {
-
+func (c *Collection[T]) addIndex(conf indexConfig[T]) *Index[T] {
 	var less func(*T, *T) bool
 
 	if conf.Unique {
@@ -160,7 +159,7 @@ func (c *Collection[T]) addIndex(conf indexConfig[T]) Index[T] {
 		BTree: btree.NewG(256, less),
 	}
 
-	index := Index[T]{
+	index := &Index[T]{
 		collectionID: c.collectionID,
 		name:         conf.Name,
 		indexID:      c.getState(c.db.Snapshot()).addIndex(indexState),
@@ -176,7 +175,7 @@ func (c *Collection[T]) addIndex(conf indexConfig[T]) Index[T] {
 	return index
 }
 
-func (c Collection[T]) Insert(tx *Snapshot, userItem *T) error {
+func (c *Collection[T]) Insert(tx *Snapshot, userItem *T) error {
 	if err := c.ensureMutable(tx); err != nil {
 		return err
 	}
@@ -203,7 +202,7 @@ func (c Collection[T]) Insert(tx *Snapshot, userItem *T) error {
 	return nil
 }
 
-func (c Collection[T]) Update(tx *Snapshot, userItem *T) error {
+func (c *Collection[T]) Update(tx *Snapshot, userItem *T) error {
 	if err := c.ensureMutable(tx); err != nil {
 		return err
 	}
@@ -235,7 +234,7 @@ func (c Collection[T]) Update(tx *Snapshot, userItem *T) error {
 	return nil
 }
 
-func (c Collection[T]) Upsert(tx *Snapshot, item *T) error {
+func (c *Collection[T]) Upsert(tx *Snapshot, item *T) error {
 	err := c.Insert(tx, item)
 	if err == nil {
 		return nil
@@ -246,7 +245,7 @@ func (c Collection[T]) Upsert(tx *Snapshot, item *T) error {
 	return err
 }
 
-func (c Collection[T]) Delete(tx *Snapshot, itemID uint64) error {
+func (c *Collection[T]) Delete(tx *Snapshot, itemID uint64) error {
 	if err := c.ensureMutable(tx); err != nil {
 		return err
 	}
@@ -254,13 +253,13 @@ func (c Collection[T]) Delete(tx *Snapshot, itemID uint64) error {
 	return c.deleteItem(tx, itemID)
 }
 
-func (c Collection[T]) getByID(tx *Snapshot, itemID uint64) (*T, bool) {
+func (c *Collection[T]) getByID(tx *Snapshot, itemID uint64) (*T, bool) {
 	x := new(T)
 	c.setID(x, itemID)
 	return c.ByID.get(tx, x)
 }
 
-func (c Collection[T]) ensureMutable(tx *Snapshot) error {
+func (c *Collection[T]) ensureMutable(tx *Snapshot) error {
 	if !tx.writable() {
 		return errs.ReadOnly
 	}
@@ -274,7 +273,7 @@ func (c Collection[T]) ensureMutable(tx *Snapshot) error {
 }
 
 // For initial data loading.
-func (c Collection[T]) insertItem(tx *Snapshot, itemID uint64, data []byte) error {
+func (c *Collection[T]) insertItem(tx *Snapshot, itemID uint64, data []byte) error {
 	item := new(T)
 	if err := json.Unmarshal(data, item); err != nil {
 		return errs.Encoding.WithErr(err).WithCollection(c.name)
@@ -295,7 +294,7 @@ func (c Collection[T]) insertItem(tx *Snapshot, itemID uint64, data []byte) erro
 	return nil
 }
 
-func (c Collection[T]) deleteItem(tx *Snapshot, itemID uint64) error {
+func (c *Collection[T]) deleteItem(tx *Snapshot, itemID uint64) error {
 	item, ok := c.getByID(tx, itemID)
 	if !ok {
 		return errs.NotFound
@@ -312,7 +311,7 @@ func (c Collection[T]) deleteItem(tx *Snapshot, itemID uint64) error {
 
 // upsertItem inserts or updates the item with itemID and the given serialized
 // form. It's called by
-func (c Collection[T]) upsertItem(tx *Snapshot, itemID uint64, data []byte) error {
+func (c *Collection[T]) upsertItem(tx *Snapshot, itemID uint64, data []byte) error {
 	item, ok := c.getByID(tx, itemID)
 	if ok {
 		tx.delete(c.collectionID, itemID)
@@ -335,14 +334,14 @@ func (c Collection[T]) upsertItem(tx *Snapshot, itemID uint64, data []byte) erro
 	return nil
 }
 
-func (c Collection[T]) getID(t *T) uint64 {
+func (c *Collection[T]) getID(t *T) uint64 {
 	return *((*uint64)(unsafe.Pointer(t)))
 }
 
-func (c Collection[T]) setID(t *T, id uint64) {
+func (c *Collection[T]) setID(t *T, id uint64) {
 	*((*uint64)(unsafe.Pointer(t))) = id
 }
 
-func (c Collection[T]) getState(tx *Snapshot) *collectionState[T] {
+func (c *Collection[T]) getState(tx *Snapshot) *collectionState[T] {
 	return tx.collections[c.collectionID].(*collectionState[T])
 }
diff --git a/mdb/db-primary.go b/mdb/db-primary.go
deleted file mode 100644
index df6ba5b..0000000
--- a/mdb/db-primary.go
+++ /dev/null
@@ -1,67 +0,0 @@
-package mdb
-
-/*
-func (db *Database) openPrimary() (err error) {
-	wal, err := cwal.Open(db.walRootDir, cwal.Config{
-		SegMinCount:  db.conf.WALSegMinCount,
-		SegMaxAgeSec: db.conf.WALSegMaxAgeSec,
-	})
-
-	pFile, err := pfile.Open(db.pageFilePath,
-
-	pFile, err := openPageFileAndReplayWAL(db.rootDir)
-	if err != nil {
-		return err
-	}
-	defer pFile.Close()
-
-	pfHeader, err := pFile.ReadHeader()
-	if err != nil {
-		return err
-	}
-
-	tx := db.Snapshot()
-	tx.seqNum = pfHeader.SeqNum
-	tx.updatedAt = pfHeader.UpdatedAt
-
-	pIndex, err := pagefile.NewIndex(pFile)
-	if err != nil {
-		return err
-	}
-
-	err = pFile.IterateAllocated(pIndex, func(cID, iID uint64, data []byte) error {
-		return db.loadItem(tx, cID, iID, data)
-	})
-	if err != nil {
-		return err
-	}
-
-	w, err := cwal.OpenWriter(db.walRootDir, &cwal.WriterConfig{
-		SegMinCount:  db.conf.WALSegMinCount,
-		SegMaxAgeSec: db.conf.WALSegMaxAgeSec,
-	})
-	if err != nil {
-		return err
-	}
-
-	db.done.Add(1)
-	go txAggregator{
-		Stop:     db.stop,
-		Done:     db.done,
-		ModChan:  db.modChan,
-		W:        w,
-		Index:    pIndex,
-		Snapshot: db.snapshot,
-	}.Run()
-
-	db.done.Add(1)
-	go (&fileWriter{
-		Stop:         db.stop,
-		Done:         db.done,
-		PageFilePath: db.pageFilePath,
-		WALRootDir:   db.walRootDir,
-	}).Run()
-
-	return nil
-}
-*/
diff --git a/mdb/db-secondary.go b/mdb/db-secondary.go
deleted file mode 100644
index f03b01f..0000000
--- a/mdb/db-secondary.go
+++ /dev/null
@@ -1,129 +0,0 @@
-package mdb
-
-/*
-func (db *Database) openSecondary() (err error) {
-	if db.shouldLoadFromPrimary() {
-		if err := db.loadFromPrimary(); err != nil {
-			return err
-		}
-	}
-
-	log.Printf("Opening page-file...")
-
-	pFile, err := openPageFileAndReplayWAL(db.rootDir)
-	if err != nil {
-		return err
-	}
-	defer pFile.Close()
-
-	pfHeader, err := pFile.ReadHeader()
-	if err != nil {
-		return err
-	}
-
-	log.Printf("Building page-file index...")
-
-	pIndex, err := pagefile.NewIndex(pFile)
-	if err != nil {
-		return err
-	}
-
-	tx := db.Snapshot()
-	tx.seqNum = pfHeader.SeqNum
-	tx.updatedAt = pfHeader.UpdatedAt
-
-	log.Printf("Loading data into memory...")
-
-	err = pFile.IterateAllocated(pIndex, func(cID, iID uint64, data []byte) error {
-		return db.loadItem(tx, cID, iID, data)
-	})
-	if err != nil {
-		return err
-	}
-
-	log.Printf("Creating writer...")
-
-	w, err := cswal.OpenWriter(db.walRootDir, &cswal.WriterConfig{
-		SegMinCount:  db.conf.WALSegMinCount,
-		SegMaxAgeSec: db.conf.WALSegMaxAgeSec,
-	})
-	if err != nil {
-		return err
-	}
-
-	db.done.Add(1)
-	go (&walFollower{
-		Stop:   db.stop,
-		Done:   db.done,
-		W:      w,
-		Client: NewClient(db.conf.PrimaryURL, db.conf.ReplicationPSK, db.conf.NetTimeout),
-	}).Run()
-
-	db.done.Add(1)
-	go (&follower{
-		Stop:         db.stop,
-		Done:         db.done,
-		WALRootDir:   db.walRootDir,
-		SeqNum:       pfHeader.SeqNum,
-		ApplyChanges: db.applyChanges,
-	}).Run()
-
-	db.done.Add(1)
-	go (&fileWriter{
-		Stop:         db.stop,
-		Done:         db.done,
-		PageFilePath: db.pageFilePath,
-		WALRootDir:   db.walRootDir,
-	}).Run()
-
-	return nil
-}
-
-func (db *Database) shouldLoadFromPrimary() bool {
-	if _, err := os.Stat(db.walRootDir); os.IsNotExist(err) {
-		log.Printf("WAL doesn't exist.")
-		return true
-	}
-	if _, err := os.Stat(db.pageFilePath); os.IsNotExist(err) {
-		log.Printf("Page-file doesn't exist.")
-		return true
-	}
-	return false
-}
-
-func (db *Database) loadFromPrimary() error {
-	client := NewClient(db.conf.PrimaryURL, db.conf.ReplicationPSK, db.conf.NetTimeout)
-	defer client.Disconnect()
-
-	log.Printf("Loading data from primary...")
-
-	if err := os.RemoveAll(db.pageFilePath); err != nil {
-		log.Printf("Failed to remove page-file: %s", err)
-		return errs.IO.WithErr(err) // Caller can retry.
-	}
-
-	if err := os.RemoveAll(db.walRootDir); err != nil {
-		log.Printf("Failed to remove WAL: %s", err)
-		return errs.IO.WithErr(err) // Caller can retry.
-	}
-
-	err := client.DownloadPageFile(db.pageFilePath+".tmp", db.pageFilePath)
-	if err != nil {
-		log.Printf("Failed to get page-file from primary: %s", err)
-		return err // Caller can retry.
-	}
-
-	pfHeader, err := pagefile.ReadHeader(db.pageFilePath)
-	if err != nil {
-		log.Printf("Failed to read page-file sequence number: %s", err)
-		return err // Caller can retry.
-	}
-
-	if err = cswal.CreateEx(db.walRootDir, pfHeader.SeqNum+1); err != nil {
-		log.Printf("Failed to initialize WAL: %s", err)
-		return err // Caller can retry.
-	}
-
-	return nil
-}
-*/
diff --git a/mdb/db-testrunner_test.go b/mdb/db-testrunner_test.go
index a812c8e..a011ffa 100644
--- a/mdb/db-testrunner_test.go
+++ b/mdb/db-testrunner_test.go
@@ -134,7 +134,7 @@ func checkSlicesEqual[T any](t *testing.T, name string, actual, expected []T) {
 	}
 }
 
-func checkMinMaxEqual[T any](t *testing.T, name string, tx *Snapshot, index Index[T], expected []T) {
+func checkMinMaxEqual[T any](t *testing.T, name string, tx *Snapshot, index *Index[T], expected []T) {
 	if len(expected) == 0 {
 		if min, ok := index.Min(tx); ok {
 			t.Fatal(min)
diff --git a/mdb/db-userdata_test.go b/mdb/db-userdata_test.go
index ce946fb..b6a786e 100644
--- a/mdb/db-userdata_test.go
+++ b/mdb/db-userdata_test.go
@@ -14,7 +14,7 @@ type UserDataItem struct {
 
 type UserData struct {
 	*Collection[UserDataItem]
-	ByName Index[UserDataItem] // Unique index on (Token).
+	ByName *Index[UserDataItem] // Unique index on (Token).
 }
 
 func NewUserDataCollection(db *Database) UserData {
diff --git a/mdb/db-users_test.go b/mdb/db-users_test.go
index 63dbcc3..4109f2f 100644
--- a/mdb/db-users_test.go
+++ b/mdb/db-users_test.go
@@ -12,9 +12,9 @@ type User struct {
 
 type Users struct {
 	*Collection[User]
-	ByEmail   Index[User] // Unique index on (Email).
-	ByName    Index[User] // Index on (Name).
-	ByBlocked Index[User] // Partial index on (Blocked,Email).
+	ByEmail   *Index[User] // Unique index on (Email).
+	ByName    *Index[User] // Index on (Name).
+	ByBlocked *Index[User] // Partial index on (Blocked,Email).
 }
 
 func NewUserCollection(db *Database) Users {
diff --git a/mdb/index.go b/mdb/index.go
index ed769ee..9335e64 100644
--- a/mdb/index.go
+++ b/mdb/index.go
@@ -10,7 +10,7 @@ func NewIndex[T any](
 	c *Collection[T],
 	name string,
 	compare func(lhs, rhs *T) int,
-) Index[T] {
+) *Index[T] {
 	return c.addIndex(indexConfig[T]{
 		Name:    name,
 		Unique:  false,
@@ -24,7 +24,7 @@ func NewPartialIndex[T any](
 	name string,
 	compare func(lhs, rhs *T) int,
 	include func(*T) bool,
-) Index[T] {
+) *Index[T] {
 	return c.addIndex(indexConfig[T]{
 		Name:    name,
 		Unique:  false,
@@ -37,7 +37,7 @@ func NewUniqueIndex[T any](
 	c *Collection[T],
 	name string,
 	compare func(lhs, rhs *T) int,
-) Index[T] {
+) *Index[T] {
 	return c.addIndex(indexConfig[T]{
 		Name:    name,
 		Unique:  true,
@@ -51,7 +51,7 @@ func NewUniquePartialIndex[T any](
 	name string,
 	compare func(lhs, rhs *T) int,
 	include func(*T) bool,
-) Index[T] {
+) *Index[T] {
 	return c.addIndex(indexConfig[T]{
 		Name:    name,
 		Unique:  true,
@@ -70,7 +70,7 @@ type Index[T any] struct {
 	copy         func(*T) *T
 }
 
-func (i Index[T]) Get(tx *Snapshot, in *T) (item *T, ok bool) {
+func (i *Index[T]) Get(tx *Snapshot, in *T) (item *T, ok bool) {
 	tPtr, ok := i.get(tx, in)
 	if !ok {
 		return item, false
@@ -78,15 +78,15 @@ func (i Index[T]) Get(tx *Snapshot, in *T) (item *T, ok bool) {
 	return i.copy(tPtr), true
 }
 
-func (i Index[T]) get(tx *Snapshot, in *T) (*T, bool) {
+func (i *Index[T]) get(tx *Snapshot, in *T) (*T, bool) {
 	return i.btree(tx).Get(in)
 }
 
-func (i Index[T]) Has(tx *Snapshot, in *T) bool {
+func (i *Index[T]) Has(tx *Snapshot, in *T) bool {
 	return i.btree(tx).Has(in)
 }
 
-func (i Index[T]) Min(tx *Snapshot) (item *T, ok bool) {
+func (i *Index[T]) Min(tx *Snapshot) (item *T, ok bool) {
 	tPtr, ok := i.btree(tx).Min()
 	if !ok {
 		return item, false
@@ -94,7 +94,7 @@ func (i Index[T]) Min(tx *Snapshot) (item *T, ok bool) {
 	return i.copy(tPtr), true
 }
 
-func (i Index[T]) Max(tx *Snapshot) (item *T, ok bool) {
+func (i *Index[T]) Max(tx *Snapshot) (item *T, ok bool) {
 	tPtr, ok := i.btree(tx).Max()
 	if !ok {
 		return item, false
@@ -102,25 +102,25 @@ func (i Index[T]) Max(tx *Snapshot) (item *T, ok bool) {
 	return i.copy(tPtr), true
 }
 
-func (i Index[T]) Ascend(tx *Snapshot, each func(*T) bool) {
+func (i *Index[T]) Ascend(tx *Snapshot, each func(*T) bool) {
 	i.btreeForIter(tx).Ascend(func(t *T) bool {
 		return each(i.copy(t))
 	})
 }
 
-func (i Index[T]) AscendAfter(tx *Snapshot, after *T, each func(*T) bool) {
+func (i *Index[T]) AscendAfter(tx *Snapshot, after *T, each func(*T) bool) {
 	i.btreeForIter(tx).AscendGreaterOrEqual(after, func(t *T) bool {
 		return each(i.copy(t))
 	})
 }
 
-func (i Index[T]) Descend(tx *Snapshot, each func(*T) bool) {
+func (i *Index[T]) Descend(tx *Snapshot, each func(*T) bool) {
 	i.btreeForIter(tx).Descend(func(t *T) bool {
 		return each(i.copy(t))
 	})
 }
 
-func (i Index[T]) DescendAfter(tx *Snapshot, after *T, each func(*T) bool) {
+func (i *Index[T]) DescendAfter(tx *Snapshot, after *T, each func(*T) bool) {
 	i.btreeForIter(tx).DescendLessOrEqual(after, func(t *T) bool {
 		return each(i.copy(t))
 	})
@@ -133,7 +133,7 @@ type ListArgs[T any] struct {
 	Limit int           // Maximum number of items to return. 0 => All.
 }
 
-func (i Index[T]) List(tx *Snapshot, args ListArgs[T], out []*T) []*T {
+func (i *Index[T]) List(tx *Snapshot, args ListArgs[T], out []*T) []*T {
 	if args.Limit < 0 {
 		return nil
 	}
@@ -176,11 +176,11 @@ func (i Index[T]) List(tx *Snapshot, args ListArgs[T], out []*T) []*T {
 
 // ----------------------------------------------------------------------------
 
-func (i Index[T]) insertConflict(tx *Snapshot, item *T) bool {
+func (i *Index[T]) insertConflict(tx *Snapshot, item *T) bool {
 	return i.btree(tx).Has(item)
 }
 
-func (i Index[T]) updateConflict(tx *Snapshot, item *T) bool {
+func (i *Index[T]) updateConflict(tx *Snapshot, item *T) bool {
 	current, ok := i.btree(tx).Get(item)
 	return ok && i.getID(current) != i.getID(item)
 }
@@ -188,7 +188,7 @@ func (i Index[T]) updateConflict(tx *Snapshot, item *T) bool {
 // This should only be called after insertConflict. Additionally, the caller
 // should ensure that the index has been properly cloned for write before
 // writing.
-func (i Index[T]) insert(tx *Snapshot, item *T) {
+func (i *Index[T]) insert(tx *Snapshot, item *T) {
 	if i.include != nil && !i.include(item) {
 		return
 	}
@@ -196,7 +196,7 @@ func (i Index[T]) insert(tx *Snapshot, item *T) {
 	i.btree(tx).ReplaceOrInsert(item)
 }
 
-func (i Index[T]) update(tx *Snapshot, old, new *T) {
+func (i *Index[T]) update(tx *Snapshot, old, new *T) {
 	bt := i.btree(tx)
 	bt.Delete(old)
 
@@ -204,22 +204,22 @@ func (i Index[T]) update(tx *Snapshot, old, new *T) {
 	i.insert(tx, new)
 }
 
-func (i Index[T]) delete(tx *Snapshot, item *T) {
+func (i *Index[T]) delete(tx *Snapshot, item *T) {
 	i.btree(tx).Delete(item)
 }
 
 // ----------------------------------------------------------------------------
 
-func (i Index[T]) getState(tx *Snapshot) indexState[T] {
+func (i *Index[T]) getState(tx *Snapshot) indexState[T] {
 	return tx.collections[i.collectionID].(*collectionState[T]).Indices[i.indexID]
 }
 
 // Get the current btree for get/has/update/delete, etc.
-func (i Index[T]) btree(tx *Snapshot) *btree.BTreeG[*T] {
+func (i *Index[T]) btree(tx *Snapshot) *btree.BTreeG[*T] {
 	return i.getState(tx).BTree
 }
 
-func (i Index[T]) btreeForIter(tx *Snapshot) *btree.BTreeG[*T] {
+func (i *Index[T]) btreeForIter(tx *Snapshot) *btree.BTreeG[*T] {
 	cState := tx.collections[i.collectionID].(*collectionState[T])
 	bt := cState.Indices[i.indexID].BTree
 
@@ -231,6 +231,6 @@ func (i Index[T]) btreeForIter(tx *Snapshot) *btree.BTreeG[*T] {
 	return bt
 }
 
-func (i Index[T]) getID(t *T) uint64 {
+func (i *Index[T]) getID(t *T) uint64 {
 	return *((*uint64)(unsafe.Pointer(t)))
 }