diff --git a/database/database.go b/database/database.go
index ca71d16a..184d0d30 100644
--- a/database/database.go
+++ b/database/database.go
@@ -131,7 +131,7 @@ func NewCustomDB(ctx context.Context, dbName string, creds DBCredentials, logger
 	if logger == nil {
 		logger = &logrus.Logger{}
 	}
-	err = ensureDBSchema(ctx, database, logger)
+	err = ensureDBSchema(ctx, database, Schema, logger)
 	if err != nil {
 		return nil, err
 	}
@@ -188,114 +188,7 @@ func connectionString(creds DBCredentials) string {
 // creates them if needed.
 // See https://docs.mongodb.com/manual/indexes/
 // See https://docs.mongodb.com/manual/core/index-unique/
-func ensureDBSchema(ctx context.Context, db *mongo.Database, log *logrus.Logger) error {
-	// schema defines a mapping between a collection name and the indexes that
-	// must exist for that collection.
-	schema := map[string][]mongo.IndexModel{
-		collUsers: {
-			{
-				Keys:    bson.D{{"sub", 1}},
-				Options: options.Index().SetName("sub_unique").SetUnique(true),
-			},
-		},
-		collSkylinks: {
-			{
-				Keys:    bson.D{{"skylink", 1}},
-				Options: options.Index().SetName("skylink_unique").SetUnique(true),
-			},
-		},
-		collUploads: {
-			{
-				Keys:    bson.D{{"user_id", 1}},
-				Options: options.Index().SetName("user_id"),
-			},
-			{
-				Keys:    bson.D{{"skylink_id", 1}},
-				Options: options.Index().SetName("skylink_id"),
-			},
-		},
-		collDownloads: {
-			{
-				Keys:    bson.D{{"user_id", 1}},
-				Options: options.Index().SetName("user_id"),
-			},
-			{
-				Keys:    bson.D{{"skylink_id", 1}},
-				Options: options.Index().SetName("skylink_id"),
-			},
-		},
-		collRegistryReads: {
-			{
-				Keys:    bson.D{{"user_id", 1}},
-				Options: options.Index().SetName("user_id"),
-			},
-		},
-		collRegistryWrites: {
-			{
-				Keys:    bson.D{{"user_id", 1}},
-				Options: options.Index().SetName("user_id"),
-			},
-		},
-		collEmails: {
-			{
-				Keys:    bson.D{{"failed_attempts", 1}},
-				Options: options.Index().SetName("failed_attempts"),
-			},
-			{
-				Keys:    bson.D{{"locked_by", 1}},
-				Options: options.Index().SetName("locked_by"),
-			},
-			{
-				Keys:    bson.D{{"sent_at", 1}},
-				Options: options.Index().SetName("sent_at"),
-			},
-			{
-				Keys:    bson.D{{"sent_by", 1}},
-				Options: options.Index().SetName("sent_by"),
-			},
-		},
-		collChallenges: {
-			{
-				Keys:    bson.D{{"challenge", 1}},
-				Options: options.Index().SetName("challenge"),
-			},
-			{
-				Keys:    bson.D{{"type", 1}},
-				Options: options.Index().SetName("type"),
-			},
-			{
-				Keys:    bson.D{{"expires_at", 1}},
-				Options: options.Index().SetName("expires_at"),
-			},
-		},
-		collUnconfirmedUserUpdates: {
-			{
-				Keys:    bson.D{{"challenge_id", 1}},
-				Options: options.Index().SetName("challenge_id"),
-			},
-			{
-				Keys:    bson.D{{"expires_at", 1}},
-				Options: options.Index().SetName("expires_at"),
-			},
-		},
-		collConfiguration: {
-			{
-				Keys:    bson.D{{"key", 1}},
-				Options: options.Index().SetName("key_unique").SetUnique(true),
-			},
-		},
-		collAPIKeys: {
-			{
-				Keys:    bson.D{{"key", 1}},
-				Options: options.Index().SetName("key_unique").SetUnique(true),
-			},
-			{
-				Keys:    bson.D{{"user_id", 1}},
-				Options: options.Index().SetName("user_id"),
-			},
-		},
-	}
-
+func ensureDBSchema(ctx context.Context, db *mongo.Database, schema map[string][]mongo.IndexModel, log *logrus.Logger) error {
 	for collName, models := range schema {
 		coll, err := ensureCollection(ctx, db, collName)
 		if err != nil {
diff --git a/database/schema.go b/database/schema.go
new file mode 100644
index 00000000..34138e35
--- /dev/null
+++ b/database/schema.go
@@ -0,0 +1,116 @@
+package database
+
+import (
+	"go.mongodb.org/mongo-driver/bson"
+	"go.mongodb.org/mongo-driver/mongo"
+	"go.mongodb.org/mongo-driver/mongo/options"
+)
+
+var (
+	// Schema defines a mapping between a collection name and the indexes that
+	// must exist for that collection.
+	Schema = map[string][]mongo.IndexModel{
+		collUsers: {
+			{
+				Keys:    bson.D{{"sub", 1}},
+				Options: options.Index().SetName("sub_unique").SetUnique(true),
+			},
+		},
+		collSkylinks: {
+			{
+				Keys:    bson.D{{"skylink", 1}},
+				Options: options.Index().SetName("skylink_unique").SetUnique(true),
+			},
+		},
+		collUploads: {
+			{
+				Keys:    bson.D{{"user_id", 1}},
+				Options: options.Index().SetName("user_id"),
+			},
+			{
+				Keys:    bson.D{{"skylink_id", 1}},
+				Options: options.Index().SetName("skylink_id"),
+			},
+		},
+		collDownloads: {
+			{
+				Keys:    bson.D{{"user_id", 1}},
+				Options: options.Index().SetName("user_id"),
+			},
+			{
+				Keys:    bson.D{{"skylink_id", 1}},
+				Options: options.Index().SetName("skylink_id"),
+			},
+		},
+		collRegistryReads: {
+			{
+				Keys:    bson.D{{"user_id", 1}},
+				Options: options.Index().SetName("user_id"),
+			},
+		},
+		collRegistryWrites: {
+			{
+				Keys:    bson.D{{"user_id", 1}},
+				Options: options.Index().SetName("user_id"),
+			},
+		},
+		collEmails: {
+			{
+				Keys:    bson.D{{"failed_attempts", 1}},
+				Options: options.Index().SetName("failed_attempts"),
+			},
+			{
+				Keys:    bson.D{{"locked_by", 1}},
+				Options: options.Index().SetName("locked_by"),
+			},
+			{
+				Keys:    bson.D{{"sent_at", 1}},
+				Options: options.Index().SetName("sent_at"),
+			},
+			{
+				Keys:    bson.D{{"sent_by", 1}},
+				Options: options.Index().SetName("sent_by"),
+			},
+		},
+		collChallenges: {
+			{
+				Keys:    bson.D{{"challenge", 1}},
+				Options: options.Index().SetName("challenge"),
+			},
+			{
+				Keys:    bson.D{{"type", 1}},
+				Options: options.Index().SetName("type"),
+			},
+			{
+				Keys:    bson.D{{"expires_at", 1}},
+				Options: options.Index().SetName("expires_at"),
+			},
+		},
+		collUnconfirmedUserUpdates: {
+			{
+				Keys:    bson.D{{"challenge_id", 1}},
+				Options: options.Index().SetName("challenge_id"),
+			},
+			{
+				Keys:    bson.D{{"expires_at", 1}},
+				Options: options.Index().SetName("expires_at"),
+			},
+		},
+		collConfiguration: {
+			{
+				Keys:    bson.D{{"key", 1}},
+				Options: options.Index().SetName("key_unique").SetUnique(true),
+			},
+		},
+		collAPIKeys: {
+			{
+				Keys:    bson.D{{"key", 1}},
+				Options: options.Index().SetName("key_unique").SetUnique(true),
+			},
+			{
+				Keys:    bson.D{{"user_id", 1}},
+				Options: options.Index().SetName("user_id"),
+			},
+		},
+	}
+)