diff --git a/server/cache.go b/server/cache.go
index 131c06b3..3a35b74b 100644
--- a/server/cache.go
+++ b/server/cache.go
@@ -1,8 +1,13 @@
 package server
 
 import (
+	"database/sql"
 	"errors"
+	"fmt"
 	_ "github.com/mattn/go-sqlite3" // SQLite driver
+	"heckel.io/ntfy/util"
+	"log"
+	"strings"
 	"time"
 )
 
@@ -10,16 +15,551 @@ var (
 	errUnexpectedMessageType = errors.New("unexpected message type")
 )
 
-// cache implements a cache for messages of type "message" events,
-// i.e. message structs with the Event messageEvent.
-type cache interface {
-	AddMessage(m *message) error
-	Messages(topic string, since sinceMarker, scheduled bool) ([]*message, error)
-	MessagesDue() ([]*message, error)
-	MessageCount(topic string) (int, error)
-	Topics() (map[string]*topic, error)
-	Prune(olderThan time.Time) error
-	MarkPublished(m *message) error
-	AttachmentsSize(owner string) (int64, error)
-	AttachmentsExpired() ([]string, error)
+// Messages cache
+const (
+	createMessagesTableQuery = `
+		BEGIN;
+		CREATE TABLE IF NOT EXISTS messages (
+			id INTEGER PRIMARY KEY AUTOINCREMENT,
+			mid TEXT NOT NULL,
+			time INT NOT NULL,
+			topic TEXT NOT NULL,
+			message TEXT NOT NULL,
+			title TEXT NOT NULL,
+			priority INT NOT NULL,
+			tags TEXT NOT NULL,
+			click TEXT NOT NULL,
+			attachment_name TEXT NOT NULL,
+			attachment_type TEXT NOT NULL,
+			attachment_size INT NOT NULL,
+			attachment_expires INT NOT NULL,
+			attachment_url TEXT NOT NULL,
+			attachment_owner TEXT NOT NULL,
+			encoding TEXT NOT NULL,
+			published INT NOT NULL
+		);
+		CREATE INDEX IF NOT EXISTS idx_mid ON messages (mid);
+		CREATE INDEX IF NOT EXISTS idx_topic ON messages (topic);
+		COMMIT;
+	`
+	insertMessageQuery = `
+		INSERT INTO messages (mid, time, topic, message, title, priority, tags, click, attachment_name, attachment_type, attachment_size, attachment_expires, attachment_url, attachment_owner, encoding, published) 
+		VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
+	`
+	pruneMessagesQuery           = `DELETE FROM messages WHERE time < ? AND published = 1`
+	selectRowIDFromMessageID     = `SELECT id FROM messages WHERE topic = ? AND mid = ?`
+	selectMessagesSinceTimeQuery = `
+		SELECT mid, time, topic, message, title, priority, tags, click, attachment_name, attachment_type, attachment_size, attachment_expires, attachment_url, attachment_owner, encoding
+		FROM messages 
+		WHERE topic = ? AND time >= ? AND published = 1
+		ORDER BY time, id
+	`
+	selectMessagesSinceTimeIncludeScheduledQuery = `
+		SELECT mid, time, topic, message, title, priority, tags, click, attachment_name, attachment_type, attachment_size, attachment_expires, attachment_url, attachment_owner, encoding
+		FROM messages 
+		WHERE topic = ? AND time >= ?
+		ORDER BY time, id
+	`
+	selectMessagesSinceIDQuery = `
+		SELECT mid, time, topic, message, title, priority, tags, click, attachment_name, attachment_type, attachment_size, attachment_expires, attachment_url, attachment_owner, encoding
+		FROM messages 
+		WHERE topic = ? AND id > ? AND published = 1 
+		ORDER BY time, id
+	`
+	selectMessagesSinceIDIncludeScheduledQuery = `
+		SELECT mid, time, topic, message, title, priority, tags, click, attachment_name, attachment_type, attachment_size, attachment_expires, attachment_url, attachment_owner, encoding
+		FROM messages 
+		WHERE topic = ? AND (id > ? OR published = 0)
+		ORDER BY time, id
+	`
+	selectMessagesDueQuery = `
+		SELECT mid, time, topic, message, title, priority, tags, click, attachment_name, attachment_type, attachment_size, attachment_expires, attachment_url, attachment_owner, encoding
+		FROM messages 
+		WHERE time <= ? AND published = 0
+		ORDER BY time, id
+	`
+	updateMessagePublishedQuery     = `UPDATE messages SET published = 1 WHERE mid = ?`
+	selectMessagesCountQuery        = `SELECT COUNT(*) FROM messages`
+	selectMessageCountForTopicQuery = `SELECT COUNT(*) FROM messages WHERE topic = ?`
+	selectTopicsQuery               = `SELECT topic FROM messages GROUP BY topic`
+	selectAttachmentsSizeQuery      = `SELECT IFNULL(SUM(attachment_size), 0) FROM messages WHERE attachment_owner = ? AND attachment_expires >= ?`
+	selectAttachmentsExpiredQuery   = `SELECT mid FROM messages WHERE attachment_expires > 0 AND attachment_expires < ?`
+)
+
+// Schema management queries
+const (
+	currentSchemaVersion          = 5
+	createSchemaVersionTableQuery = `
+		CREATE TABLE IF NOT EXISTS schemaVersion (
+			id INT PRIMARY KEY,
+			version INT NOT NULL
+		);
+	`
+	insertSchemaVersion      = `INSERT INTO schemaVersion VALUES (1, ?)`
+	updateSchemaVersion      = `UPDATE schemaVersion SET version = ? WHERE id = 1`
+	selectSchemaVersionQuery = `SELECT version FROM schemaVersion WHERE id = 1`
+
+	// 0 -> 1
+	migrate0To1AlterMessagesTableQuery = `
+		BEGIN;
+		ALTER TABLE messages ADD COLUMN title TEXT NOT NULL DEFAULT('');
+		ALTER TABLE messages ADD COLUMN priority INT NOT NULL DEFAULT(0);
+		ALTER TABLE messages ADD COLUMN tags TEXT NOT NULL DEFAULT('');
+		COMMIT;
+	`
+
+	// 1 -> 2
+	migrate1To2AlterMessagesTableQuery = `
+		ALTER TABLE messages ADD COLUMN published INT NOT NULL DEFAULT(1);
+	`
+
+	// 2 -> 3
+	migrate2To3AlterMessagesTableQuery = `
+		BEGIN;
+		ALTER TABLE messages ADD COLUMN click TEXT NOT NULL DEFAULT('');
+		ALTER TABLE messages ADD COLUMN attachment_name TEXT NOT NULL DEFAULT('');
+		ALTER TABLE messages ADD COLUMN attachment_type TEXT NOT NULL DEFAULT('');
+		ALTER TABLE messages ADD COLUMN attachment_size INT NOT NULL DEFAULT('0');
+		ALTER TABLE messages ADD COLUMN attachment_expires INT NOT NULL DEFAULT('0');
+		ALTER TABLE messages ADD COLUMN attachment_owner TEXT NOT NULL DEFAULT('');
+		ALTER TABLE messages ADD COLUMN attachment_url TEXT NOT NULL DEFAULT('');
+		COMMIT;
+	`
+	// 3 -> 4
+	migrate3To4AlterMessagesTableQuery = `
+		ALTER TABLE messages ADD COLUMN encoding TEXT NOT NULL DEFAULT('');
+	`
+
+	// 4 -> 5
+	migrate4To5AlterMessagesTableQuery = `
+		BEGIN;
+		CREATE TABLE IF NOT EXISTS messages_new (
+			id INTEGER PRIMARY KEY AUTOINCREMENT,
+			mid TEXT NOT NULL,
+			time INT NOT NULL,
+			topic TEXT NOT NULL,
+			message TEXT NOT NULL,
+			title TEXT NOT NULL,
+			priority INT NOT NULL,
+			tags TEXT NOT NULL,
+			click TEXT NOT NULL,
+			attachment_name TEXT NOT NULL,
+			attachment_type TEXT NOT NULL,
+			attachment_size INT NOT NULL,
+			attachment_expires INT NOT NULL,
+			attachment_url TEXT NOT NULL,
+			attachment_owner TEXT NOT NULL,
+			encoding TEXT NOT NULL,
+			published INT NOT NULL
+		);
+		CREATE INDEX IF NOT EXISTS idx_mid ON messages_new (mid);
+		CREATE INDEX IF NOT EXISTS idx_topic ON messages_new (topic);
+		INSERT 
+			INTO messages_new (
+				mid, time, topic, message, title, priority, tags, click, attachment_name, attachment_type, 
+				attachment_size, attachment_expires, attachment_url, attachment_owner, encoding, published)
+			SELECT
+				id, time, topic, message, title, priority, tags, click, attachment_name, attachment_type, 
+				attachment_size, attachment_expires, attachment_url, attachment_owner, encoding, published
+			FROM messages;
+		DROP TABLE messages;
+		ALTER TABLE messages_new RENAME TO messages;
+		COMMIT;
+	`
+)
+
+type sqliteCache struct {
+	db  *sql.DB
+	nop bool
+}
+
+func newSqliteCache(filename string, nop bool) (*sqliteCache, error) {
+	db, err := sql.Open("sqlite3", filename)
+	if err != nil {
+		return nil, err
+	}
+	if err := setupCacheDB(db); err != nil {
+		return nil, err
+	}
+	return &sqliteCache{
+		db:  db,
+		nop: nop,
+	}, nil
+}
+
+// newMemCache creates an in-memory cache
+func newMemCache() (*sqliteCache, error) {
+	return newSqliteCache(createMemoryFilename(), false)
+}
+
+// newNopCache creates an in-memory cache that discards all messages;
+// it is always empty and can be used if caching is entirely disabled
+func newNopCache() (*sqliteCache, error) {
+	return newSqliteCache(createMemoryFilename(), true)
+}
+
+// createMemoryFilename creates a unique memory filename to use for the SQLite backend.
+// From mattn/go-sqlite3: "Each connection to ":memory:" opens a brand new in-memory
+// sql database, so if the stdlib's sql engine happens to open another connection and
+// you've only specified ":memory:", that connection will see a brand new database.
+// A workaround is to use "file::memory:?cache=shared" (or "file:foobar?mode=memory&cache=shared").
+// Every connection to this string will point to the same in-memory database."
+func createMemoryFilename() string {
+	return fmt.Sprintf("file:%s?mode=memory&cache=shared", util.RandomString(10))
+}
+
+func (c *sqliteCache) AddMessage(m *message) error {
+	if m.Event != messageEvent {
+		return errUnexpectedMessageType
+	}
+	if c.nop {
+		return nil
+	}
+	published := m.Time <= time.Now().Unix()
+	tags := strings.Join(m.Tags, ",")
+	var attachmentName, attachmentType, attachmentURL, attachmentOwner string
+	var attachmentSize, attachmentExpires int64
+	if m.Attachment != nil {
+		attachmentName = m.Attachment.Name
+		attachmentType = m.Attachment.Type
+		attachmentSize = m.Attachment.Size
+		attachmentExpires = m.Attachment.Expires
+		attachmentURL = m.Attachment.URL
+		attachmentOwner = m.Attachment.Owner
+	}
+	_, err := c.db.Exec(
+		insertMessageQuery,
+		m.ID,
+		m.Time,
+		m.Topic,
+		m.Message,
+		m.Title,
+		m.Priority,
+		tags,
+		m.Click,
+		attachmentName,
+		attachmentType,
+		attachmentSize,
+		attachmentExpires,
+		attachmentURL,
+		attachmentOwner,
+		m.Encoding,
+		published,
+	)
+	return err
+}
+
+func (c *sqliteCache) Messages(topic string, since sinceMarker, scheduled bool) ([]*message, error) {
+	if since.IsNone() {
+		return make([]*message, 0), nil
+	} else if since.IsID() {
+		return c.messagesSinceID(topic, since, scheduled)
+	}
+	return c.messagesSinceTime(topic, since, scheduled)
+}
+
+func (c *sqliteCache) messagesSinceTime(topic string, since sinceMarker, scheduled bool) ([]*message, error) {
+	var rows *sql.Rows
+	var err error
+	if scheduled {
+		rows, err = c.db.Query(selectMessagesSinceTimeIncludeScheduledQuery, topic, since.Time().Unix())
+	} else {
+		rows, err = c.db.Query(selectMessagesSinceTimeQuery, topic, since.Time().Unix())
+	}
+	if err != nil {
+		return nil, err
+	}
+	return readMessages(rows)
+}
+
+func (c *sqliteCache) messagesSinceID(topic string, since sinceMarker, scheduled bool) ([]*message, error) {
+	idrows, err := c.db.Query(selectRowIDFromMessageID, topic, since.ID())
+	if err != nil {
+		return nil, err
+	}
+	defer idrows.Close()
+	if !idrows.Next() {
+		return c.messagesSinceTime(topic, sinceAllMessages, scheduled)
+	}
+	var rowID int64
+	if err := idrows.Scan(&rowID); err != nil {
+		return nil, err
+	}
+	idrows.Close()
+	var rows *sql.Rows
+	if scheduled {
+		rows, err = c.db.Query(selectMessagesSinceIDIncludeScheduledQuery, topic, rowID)
+	} else {
+		rows, err = c.db.Query(selectMessagesSinceIDQuery, topic, rowID)
+	}
+	if err != nil {
+		return nil, err
+	}
+	return readMessages(rows)
+}
+
+func (c *sqliteCache) MessagesDue() ([]*message, error) {
+	rows, err := c.db.Query(selectMessagesDueQuery, time.Now().Unix())
+	if err != nil {
+		return nil, err
+	}
+	return readMessages(rows)
+}
+
+func (c *sqliteCache) MarkPublished(m *message) error {
+	_, err := c.db.Exec(updateMessagePublishedQuery, m.ID)
+	return err
+}
+
+func (c *sqliteCache) MessageCount(topic string) (int, error) {
+	rows, err := c.db.Query(selectMessageCountForTopicQuery, topic)
+	if err != nil {
+		return 0, err
+	}
+	defer rows.Close()
+	var count int
+	if !rows.Next() {
+		return 0, errors.New("no rows found")
+	}
+	if err := rows.Scan(&count); err != nil {
+		return 0, err
+	} else if err := rows.Err(); err != nil {
+		return 0, err
+	}
+	return count, nil
+}
+
+func (c *sqliteCache) Topics() (map[string]*topic, error) {
+	rows, err := c.db.Query(selectTopicsQuery)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	topics := make(map[string]*topic)
+	for rows.Next() {
+		var id string
+		if err := rows.Scan(&id); err != nil {
+			return nil, err
+		}
+		topics[id] = newTopic(id)
+	}
+	if err := rows.Err(); err != nil {
+		return nil, err
+	}
+	return topics, nil
+}
+
+func (c *sqliteCache) Prune(olderThan time.Time) error {
+	_, err := c.db.Exec(pruneMessagesQuery, olderThan.Unix())
+	return err
+}
+
+func (c *sqliteCache) AttachmentsSize(owner string) (int64, error) {
+	rows, err := c.db.Query(selectAttachmentsSizeQuery, owner, time.Now().Unix())
+	if err != nil {
+		return 0, err
+	}
+	defer rows.Close()
+	var size int64
+	if !rows.Next() {
+		return 0, errors.New("no rows found")
+	}
+	if err := rows.Scan(&size); err != nil {
+		return 0, err
+	} else if err := rows.Err(); err != nil {
+		return 0, err
+	}
+	return size, nil
+}
+
+func (c *sqliteCache) AttachmentsExpired() ([]string, error) {
+	rows, err := c.db.Query(selectAttachmentsExpiredQuery, time.Now().Unix())
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	ids := make([]string, 0)
+	for rows.Next() {
+		var id string
+		if err := rows.Scan(&id); err != nil {
+			return nil, err
+		}
+		ids = append(ids, id)
+	}
+	if err := rows.Err(); err != nil {
+		return nil, err
+	}
+	return ids, nil
+}
+
+func readMessages(rows *sql.Rows) ([]*message, error) {
+	defer rows.Close()
+	messages := make([]*message, 0)
+	for rows.Next() {
+		var timestamp, attachmentSize, attachmentExpires int64
+		var priority int
+		var id, topic, msg, title, tagsStr, click, attachmentName, attachmentType, attachmentURL, attachmentOwner, encoding string
+		err := rows.Scan(
+			&id,
+			&timestamp,
+			&topic,
+			&msg,
+			&title,
+			&priority,
+			&tagsStr,
+			&click,
+			&attachmentName,
+			&attachmentType,
+			&attachmentSize,
+			&attachmentExpires,
+			&attachmentURL,
+			&attachmentOwner,
+			&encoding,
+		)
+		if err != nil {
+			return nil, err
+		}
+		var tags []string
+		if tagsStr != "" {
+			tags = strings.Split(tagsStr, ",")
+		}
+		var att *attachment
+		if attachmentName != "" && attachmentURL != "" {
+			att = &attachment{
+				Name:    attachmentName,
+				Type:    attachmentType,
+				Size:    attachmentSize,
+				Expires: attachmentExpires,
+				URL:     attachmentURL,
+				Owner:   attachmentOwner,
+			}
+		}
+		messages = append(messages, &message{
+			ID:         id,
+			Time:       timestamp,
+			Event:      messageEvent,
+			Topic:      topic,
+			Message:    msg,
+			Title:      title,
+			Priority:   priority,
+			Tags:       tags,
+			Click:      click,
+			Attachment: att,
+			Encoding:   encoding,
+		})
+	}
+	if err := rows.Err(); err != nil {
+		return nil, err
+	}
+	return messages, nil
+}
+
+func setupCacheDB(db *sql.DB) error {
+	// If 'messages' table does not exist, this must be a new database
+	rowsMC, err := db.Query(selectMessagesCountQuery)
+	if err != nil {
+		return setupNewCacheDB(db)
+	}
+	rowsMC.Close()
+
+	// If 'messages' table exists, check 'schemaVersion' table
+	schemaVersion := 0
+	rowsSV, err := db.Query(selectSchemaVersionQuery)
+	if err == nil {
+		defer rowsSV.Close()
+		if !rowsSV.Next() {
+			return errors.New("cannot determine schema version: cache file may be corrupt")
+		}
+		if err := rowsSV.Scan(&schemaVersion); err != nil {
+			return err
+		}
+		rowsSV.Close()
+	}
+
+	// Do migrations
+	if schemaVersion == currentSchemaVersion {
+		return nil
+	} else if schemaVersion == 0 {
+		return migrateFrom0(db)
+	} else if schemaVersion == 1 {
+		return migrateFrom1(db)
+	} else if schemaVersion == 2 {
+		return migrateFrom2(db)
+	} else if schemaVersion == 3 {
+		return migrateFrom3(db)
+	} else if schemaVersion == 4 {
+		return migrateFrom4(db)
+	}
+	return fmt.Errorf("unexpected schema version found: %d", schemaVersion)
+}
+
+func setupNewCacheDB(db *sql.DB) error {
+	if _, err := db.Exec(createMessagesTableQuery); err != nil {
+		return err
+	}
+	if _, err := db.Exec(createSchemaVersionTableQuery); err != nil {
+		return err
+	}
+	if _, err := db.Exec(insertSchemaVersion, currentSchemaVersion); err != nil {
+		return err
+	}
+	return nil
+}
+
+func migrateFrom0(db *sql.DB) error {
+	log.Print("Migrating cache database schema: from 0 to 1")
+	if _, err := db.Exec(migrate0To1AlterMessagesTableQuery); err != nil {
+		return err
+	}
+	if _, err := db.Exec(createSchemaVersionTableQuery); err != nil {
+		return err
+	}
+	if _, err := db.Exec(insertSchemaVersion, 1); err != nil {
+		return err
+	}
+	return migrateFrom1(db)
+}
+
+func migrateFrom1(db *sql.DB) error {
+	log.Print("Migrating cache database schema: from 1 to 2")
+	if _, err := db.Exec(migrate1To2AlterMessagesTableQuery); err != nil {
+		return err
+	}
+	if _, err := db.Exec(updateSchemaVersion, 2); err != nil {
+		return err
+	}
+	return migrateFrom2(db)
+}
+
+func migrateFrom2(db *sql.DB) error {
+	log.Print("Migrating cache database schema: from 2 to 3")
+	if _, err := db.Exec(migrate2To3AlterMessagesTableQuery); err != nil {
+		return err
+	}
+	if _, err := db.Exec(updateSchemaVersion, 3); err != nil {
+		return err
+	}
+	return migrateFrom3(db)
+}
+
+func migrateFrom3(db *sql.DB) error {
+	log.Print("Migrating cache database schema: from 3 to 4")
+	if _, err := db.Exec(migrate3To4AlterMessagesTableQuery); err != nil {
+		return err
+	}
+	if _, err := db.Exec(updateSchemaVersion, 4); err != nil {
+		return err
+	}
+	return migrateFrom4(db)
+}
+
+func migrateFrom4(db *sql.DB) error {
+	log.Print("Migrating cache database schema: from 4 to 5")
+	if _, err := db.Exec(migrate4To5AlterMessagesTableQuery); err != nil {
+		return err
+	}
+	if _, err := db.Exec(updateSchemaVersion, 5); err != nil {
+		return err
+	}
+	return nil // Update this when a new version is added
 }
diff --git a/server/cache_mem_test.go b/server/cache_mem_test.go
deleted file mode 100644
index 561f461e..00000000
--- a/server/cache_mem_test.go
+++ /dev/null
@@ -1,55 +0,0 @@
-package server
-
-import (
-	"github.com/stretchr/testify/assert"
-	"testing"
-)
-
-func TestMemCache_Messages(t *testing.T) {
-	testCacheMessages(t, newMemTestCache(t))
-}
-
-func TestMemCache_MessagesScheduled(t *testing.T) {
-	testCacheMessagesScheduled(t, newMemTestCache(t))
-}
-
-func TestMemCache_Topics(t *testing.T) {
-	testCacheTopics(t, newMemTestCache(t))
-}
-
-func TestMemCache_MessagesTagsPrioAndTitle(t *testing.T) {
-	testCacheMessagesTagsPrioAndTitle(t, newMemTestCache(t))
-}
-
-func TestMemCache_MessagesSinceID(t *testing.T) {
-	testCacheMessagesSinceID(t, newMemTestCache(t))
-}
-
-func TestMemCache_Prune(t *testing.T) {
-	testCachePrune(t, newMemTestCache(t))
-}
-
-func TestMemCache_Attachments(t *testing.T) {
-	testCacheAttachments(t, newMemTestCache(t))
-}
-
-func TestMemCache_NopCache(t *testing.T) {
-	c, _ := newNopCache()
-	assert.Nil(t, c.AddMessage(newDefaultMessage("mytopic", "my message")))
-
-	messages, err := c.Messages("mytopic", sinceAllMessages, false)
-	assert.Nil(t, err)
-	assert.Empty(t, messages)
-
-	topics, err := c.Topics()
-	assert.Nil(t, err)
-	assert.Empty(t, topics)
-}
-
-func newMemTestCache(t *testing.T) cache {
-	c, err := newMemCache()
-	if err != nil {
-		t.Fatal(err)
-	}
-	return c
-}
diff --git a/server/cache_sqlite.go b/server/cache_sqlite.go
deleted file mode 100644
index 4b53ff17..00000000
--- a/server/cache_sqlite.go
+++ /dev/null
@@ -1,563 +0,0 @@
-package server
-
-import (
-	"database/sql"
-	"errors"
-	"fmt"
-	_ "github.com/mattn/go-sqlite3" // SQLite driver
-	"heckel.io/ntfy/util"
-	"log"
-	"strings"
-	"time"
-)
-
-// Messages cache
-const (
-	createMessagesTableQuery = `
-		BEGIN;
-		CREATE TABLE IF NOT EXISTS messages (
-			id INTEGER PRIMARY KEY AUTOINCREMENT,
-			mid TEXT NOT NULL,
-			time INT NOT NULL,
-			topic TEXT NOT NULL,
-			message TEXT NOT NULL,
-			title TEXT NOT NULL,
-			priority INT NOT NULL,
-			tags TEXT NOT NULL,
-			click TEXT NOT NULL,
-			attachment_name TEXT NOT NULL,
-			attachment_type TEXT NOT NULL,
-			attachment_size INT NOT NULL,
-			attachment_expires INT NOT NULL,
-			attachment_url TEXT NOT NULL,
-			attachment_owner TEXT NOT NULL,
-			encoding TEXT NOT NULL,
-			published INT NOT NULL
-		);
-		CREATE INDEX IF NOT EXISTS idx_mid ON messages (mid);
-		CREATE INDEX IF NOT EXISTS idx_topic ON messages (topic);
-		COMMIT;
-	`
-	insertMessageQuery = `
-		INSERT INTO messages (mid, time, topic, message, title, priority, tags, click, attachment_name, attachment_type, attachment_size, attachment_expires, attachment_url, attachment_owner, encoding, published) 
-		VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
-	`
-	pruneMessagesQuery           = `DELETE FROM messages WHERE time < ? AND published = 1`
-	selectRowIDFromMessageID     = `SELECT id FROM messages WHERE topic = ? AND mid = ?`
-	selectMessagesSinceTimeQuery = `
-		SELECT mid, time, topic, message, title, priority, tags, click, attachment_name, attachment_type, attachment_size, attachment_expires, attachment_url, attachment_owner, encoding
-		FROM messages 
-		WHERE topic = ? AND time >= ? AND published = 1
-		ORDER BY time, id
-	`
-	selectMessagesSinceTimeIncludeScheduledQuery = `
-		SELECT mid, time, topic, message, title, priority, tags, click, attachment_name, attachment_type, attachment_size, attachment_expires, attachment_url, attachment_owner, encoding
-		FROM messages 
-		WHERE topic = ? AND time >= ?
-		ORDER BY time, id
-	`
-	selectMessagesSinceIDQuery = `
-		SELECT mid, time, topic, message, title, priority, tags, click, attachment_name, attachment_type, attachment_size, attachment_expires, attachment_url, attachment_owner, encoding
-		FROM messages 
-		WHERE topic = ? AND id > ? AND published = 1 
-		ORDER BY time, id
-	`
-	selectMessagesSinceIDIncludeScheduledQuery = `
-		SELECT mid, time, topic, message, title, priority, tags, click, attachment_name, attachment_type, attachment_size, attachment_expires, attachment_url, attachment_owner, encoding
-		FROM messages 
-		WHERE topic = ? AND (id > ? OR published = 0)
-		ORDER BY time, id
-	`
-	selectMessagesDueQuery = `
-		SELECT mid, time, topic, message, title, priority, tags, click, attachment_name, attachment_type, attachment_size, attachment_expires, attachment_url, attachment_owner, encoding
-		FROM messages 
-		WHERE time <= ? AND published = 0
-		ORDER BY time, id
-	`
-	updateMessagePublishedQuery     = `UPDATE messages SET published = 1 WHERE mid = ?`
-	selectMessagesCountQuery        = `SELECT COUNT(*) FROM messages`
-	selectMessageCountForTopicQuery = `SELECT COUNT(*) FROM messages WHERE topic = ?`
-	selectTopicsQuery               = `SELECT topic FROM messages GROUP BY topic`
-	selectAttachmentsSizeQuery      = `SELECT IFNULL(SUM(attachment_size), 0) FROM messages WHERE attachment_owner = ? AND attachment_expires >= ?`
-	selectAttachmentsExpiredQuery   = `SELECT mid FROM messages WHERE attachment_expires > 0 AND attachment_expires < ?`
-)
-
-// Schema management queries
-const (
-	currentSchemaVersion          = 5
-	createSchemaVersionTableQuery = `
-		CREATE TABLE IF NOT EXISTS schemaVersion (
-			id INT PRIMARY KEY,
-			version INT NOT NULL
-		);
-	`
-	insertSchemaVersion      = `INSERT INTO schemaVersion VALUES (1, ?)`
-	updateSchemaVersion      = `UPDATE schemaVersion SET version = ? WHERE id = 1`
-	selectSchemaVersionQuery = `SELECT version FROM schemaVersion WHERE id = 1`
-
-	// 0 -> 1
-	migrate0To1AlterMessagesTableQuery = `
-		BEGIN;
-		ALTER TABLE messages ADD COLUMN title TEXT NOT NULL DEFAULT('');
-		ALTER TABLE messages ADD COLUMN priority INT NOT NULL DEFAULT(0);
-		ALTER TABLE messages ADD COLUMN tags TEXT NOT NULL DEFAULT('');
-		COMMIT;
-	`
-
-	// 1 -> 2
-	migrate1To2AlterMessagesTableQuery = `
-		ALTER TABLE messages ADD COLUMN published INT NOT NULL DEFAULT(1);
-	`
-
-	// 2 -> 3
-	migrate2To3AlterMessagesTableQuery = `
-		BEGIN;
-		ALTER TABLE messages ADD COLUMN click TEXT NOT NULL DEFAULT('');
-		ALTER TABLE messages ADD COLUMN attachment_name TEXT NOT NULL DEFAULT('');
-		ALTER TABLE messages ADD COLUMN attachment_type TEXT NOT NULL DEFAULT('');
-		ALTER TABLE messages ADD COLUMN attachment_size INT NOT NULL DEFAULT('0');
-		ALTER TABLE messages ADD COLUMN attachment_expires INT NOT NULL DEFAULT('0');
-		ALTER TABLE messages ADD COLUMN attachment_owner TEXT NOT NULL DEFAULT('');
-		ALTER TABLE messages ADD COLUMN attachment_url TEXT NOT NULL DEFAULT('');
-		COMMIT;
-	`
-	// 3 -> 4
-	migrate3To4AlterMessagesTableQuery = `
-		ALTER TABLE messages ADD COLUMN encoding TEXT NOT NULL DEFAULT('');
-	`
-
-	// 4 -> 5
-	migrate4To5AlterMessagesTableQuery = `
-		BEGIN;
-		CREATE TABLE IF NOT EXISTS messages_new (
-			id INTEGER PRIMARY KEY AUTOINCREMENT,
-			mid TEXT NOT NULL,
-			time INT NOT NULL,
-			topic TEXT NOT NULL,
-			message TEXT NOT NULL,
-			title TEXT NOT NULL,
-			priority INT NOT NULL,
-			tags TEXT NOT NULL,
-			click TEXT NOT NULL,
-			attachment_name TEXT NOT NULL,
-			attachment_type TEXT NOT NULL,
-			attachment_size INT NOT NULL,
-			attachment_expires INT NOT NULL,
-			attachment_url TEXT NOT NULL,
-			attachment_owner TEXT NOT NULL,
-			encoding TEXT NOT NULL,
-			published INT NOT NULL
-		);
-		CREATE INDEX IF NOT EXISTS idx_mid ON messages_new (mid);
-		CREATE INDEX IF NOT EXISTS idx_topic ON messages_new (topic);
-		INSERT 
-			INTO messages_new (
-				mid, time, topic, message, title, priority, tags, click, attachment_name, attachment_type, 
-				attachment_size, attachment_expires, attachment_url, attachment_owner, encoding, published)
-			SELECT
-				id, time, topic, message, title, priority, tags, click, attachment_name, attachment_type, 
-				attachment_size, attachment_expires, attachment_url, attachment_owner, encoding, published
-			FROM messages;
-		DROP TABLE messages;
-		ALTER TABLE messages_new RENAME TO messages;
-		COMMIT;
-	`
-)
-
-type sqliteCache struct {
-	db  *sql.DB
-	nop bool
-}
-
-var _ cache = (*sqliteCache)(nil)
-
-func newSqliteCache(filename string, nop bool) (*sqliteCache, error) {
-	db, err := sql.Open("sqlite3", filename)
-	if err != nil {
-		return nil, err
-	}
-	if err := setupCacheDB(db); err != nil {
-		return nil, err
-	}
-	return &sqliteCache{
-		db:  db,
-		nop: nop,
-	}, nil
-}
-
-// newMemCache creates an in-memory cache
-func newMemCache() (*sqliteCache, error) {
-	return newSqliteCache(createMemoryFilename(), false)
-}
-
-// newNopCache creates an in-memory cache that discards all messages;
-// it is always empty and can be used if caching is entirely disabled
-func newNopCache() (*sqliteCache, error) {
-	return newSqliteCache(createMemoryFilename(), true)
-}
-
-// createMemoryFilename creates a unique memory filename to use for the SQLite backend.
-// From mattn/go-sqlite3: "Each connection to ":memory:" opens a brand new in-memory
-// sql database, so if the stdlib's sql engine happens to open another connection and
-// you've only specified ":memory:", that connection will see a brand new database.
-// A workaround is to use "file::memory:?cache=shared" (or "file:foobar?mode=memory&cache=shared").
-// Every connection to this string will point to the same in-memory database."
-func createMemoryFilename() string {
-	return fmt.Sprintf("file:%s?mode=memory&cache=shared", util.RandomString(10))
-}
-
-func (c *sqliteCache) AddMessage(m *message) error {
-	if m.Event != messageEvent {
-		return errUnexpectedMessageType
-	}
-	if c.nop {
-		return nil
-	}
-	published := m.Time <= time.Now().Unix()
-	tags := strings.Join(m.Tags, ",")
-	var attachmentName, attachmentType, attachmentURL, attachmentOwner string
-	var attachmentSize, attachmentExpires int64
-	if m.Attachment != nil {
-		attachmentName = m.Attachment.Name
-		attachmentType = m.Attachment.Type
-		attachmentSize = m.Attachment.Size
-		attachmentExpires = m.Attachment.Expires
-		attachmentURL = m.Attachment.URL
-		attachmentOwner = m.Attachment.Owner
-	}
-	_, err := c.db.Exec(
-		insertMessageQuery,
-		m.ID,
-		m.Time,
-		m.Topic,
-		m.Message,
-		m.Title,
-		m.Priority,
-		tags,
-		m.Click,
-		attachmentName,
-		attachmentType,
-		attachmentSize,
-		attachmentExpires,
-		attachmentURL,
-		attachmentOwner,
-		m.Encoding,
-		published,
-	)
-	return err
-}
-
-func (c *sqliteCache) Messages(topic string, since sinceMarker, scheduled bool) ([]*message, error) {
-	if since.IsNone() {
-		return make([]*message, 0), nil
-	} else if since.IsID() {
-		return c.messagesSinceID(topic, since, scheduled)
-	}
-	return c.messagesSinceTime(topic, since, scheduled)
-}
-
-func (c *sqliteCache) messagesSinceTime(topic string, since sinceMarker, scheduled bool) ([]*message, error) {
-	var rows *sql.Rows
-	var err error
-	if scheduled {
-		rows, err = c.db.Query(selectMessagesSinceTimeIncludeScheduledQuery, topic, since.Time().Unix())
-	} else {
-		rows, err = c.db.Query(selectMessagesSinceTimeQuery, topic, since.Time().Unix())
-	}
-	if err != nil {
-		return nil, err
-	}
-	return readMessages(rows)
-}
-
-func (c *sqliteCache) messagesSinceID(topic string, since sinceMarker, scheduled bool) ([]*message, error) {
-	idrows, err := c.db.Query(selectRowIDFromMessageID, topic, since.ID())
-	if err != nil {
-		return nil, err
-	}
-	defer idrows.Close()
-	if !idrows.Next() {
-		return c.messagesSinceTime(topic, sinceAllMessages, scheduled)
-	}
-	var rowID int64
-	if err := idrows.Scan(&rowID); err != nil {
-		return nil, err
-	}
-	idrows.Close()
-	var rows *sql.Rows
-	if scheduled {
-		rows, err = c.db.Query(selectMessagesSinceIDIncludeScheduledQuery, topic, rowID)
-	} else {
-		rows, err = c.db.Query(selectMessagesSinceIDQuery, topic, rowID)
-	}
-	if err != nil {
-		return nil, err
-	}
-	return readMessages(rows)
-}
-
-func (c *sqliteCache) MessagesDue() ([]*message, error) {
-	rows, err := c.db.Query(selectMessagesDueQuery, time.Now().Unix())
-	if err != nil {
-		return nil, err
-	}
-	return readMessages(rows)
-}
-
-func (c *sqliteCache) MarkPublished(m *message) error {
-	_, err := c.db.Exec(updateMessagePublishedQuery, m.ID)
-	return err
-}
-
-func (c *sqliteCache) MessageCount(topic string) (int, error) {
-	rows, err := c.db.Query(selectMessageCountForTopicQuery, topic)
-	if err != nil {
-		return 0, err
-	}
-	defer rows.Close()
-	var count int
-	if !rows.Next() {
-		return 0, errors.New("no rows found")
-	}
-	if err := rows.Scan(&count); err != nil {
-		return 0, err
-	} else if err := rows.Err(); err != nil {
-		return 0, err
-	}
-	return count, nil
-}
-
-func (c *sqliteCache) Topics() (map[string]*topic, error) {
-	rows, err := c.db.Query(selectTopicsQuery)
-	if err != nil {
-		return nil, err
-	}
-	defer rows.Close()
-	topics := make(map[string]*topic)
-	for rows.Next() {
-		var id string
-		if err := rows.Scan(&id); err != nil {
-			return nil, err
-		}
-		topics[id] = newTopic(id)
-	}
-	if err := rows.Err(); err != nil {
-		return nil, err
-	}
-	return topics, nil
-}
-
-func (c *sqliteCache) Prune(olderThan time.Time) error {
-	_, err := c.db.Exec(pruneMessagesQuery, olderThan.Unix())
-	return err
-}
-
-func (c *sqliteCache) AttachmentsSize(owner string) (int64, error) {
-	rows, err := c.db.Query(selectAttachmentsSizeQuery, owner, time.Now().Unix())
-	if err != nil {
-		return 0, err
-	}
-	defer rows.Close()
-	var size int64
-	if !rows.Next() {
-		return 0, errors.New("no rows found")
-	}
-	if err := rows.Scan(&size); err != nil {
-		return 0, err
-	} else if err := rows.Err(); err != nil {
-		return 0, err
-	}
-	return size, nil
-}
-
-func (c *sqliteCache) AttachmentsExpired() ([]string, error) {
-	rows, err := c.db.Query(selectAttachmentsExpiredQuery, time.Now().Unix())
-	if err != nil {
-		return nil, err
-	}
-	defer rows.Close()
-	ids := make([]string, 0)
-	for rows.Next() {
-		var id string
-		if err := rows.Scan(&id); err != nil {
-			return nil, err
-		}
-		ids = append(ids, id)
-	}
-	if err := rows.Err(); err != nil {
-		return nil, err
-	}
-	return ids, nil
-}
-
-func readMessages(rows *sql.Rows) ([]*message, error) {
-	defer rows.Close()
-	messages := make([]*message, 0)
-	for rows.Next() {
-		var timestamp, attachmentSize, attachmentExpires int64
-		var priority int
-		var id, topic, msg, title, tagsStr, click, attachmentName, attachmentType, attachmentURL, attachmentOwner, encoding string
-		err := rows.Scan(
-			&id,
-			&timestamp,
-			&topic,
-			&msg,
-			&title,
-			&priority,
-			&tagsStr,
-			&click,
-			&attachmentName,
-			&attachmentType,
-			&attachmentSize,
-			&attachmentExpires,
-			&attachmentURL,
-			&attachmentOwner,
-			&encoding,
-		)
-		if err != nil {
-			return nil, err
-		}
-		var tags []string
-		if tagsStr != "" {
-			tags = strings.Split(tagsStr, ",")
-		}
-		var att *attachment
-		if attachmentName != "" && attachmentURL != "" {
-			att = &attachment{
-				Name:    attachmentName,
-				Type:    attachmentType,
-				Size:    attachmentSize,
-				Expires: attachmentExpires,
-				URL:     attachmentURL,
-				Owner:   attachmentOwner,
-			}
-		}
-		messages = append(messages, &message{
-			ID:         id,
-			Time:       timestamp,
-			Event:      messageEvent,
-			Topic:      topic,
-			Message:    msg,
-			Title:      title,
-			Priority:   priority,
-			Tags:       tags,
-			Click:      click,
-			Attachment: att,
-			Encoding:   encoding,
-		})
-	}
-	if err := rows.Err(); err != nil {
-		return nil, err
-	}
-	return messages, nil
-}
-
-func setupCacheDB(db *sql.DB) error {
-	// If 'messages' table does not exist, this must be a new database
-	rowsMC, err := db.Query(selectMessagesCountQuery)
-	if err != nil {
-		return setupNewCacheDB(db)
-	}
-	rowsMC.Close()
-
-	// If 'messages' table exists, check 'schemaVersion' table
-	schemaVersion := 0
-	rowsSV, err := db.Query(selectSchemaVersionQuery)
-	if err == nil {
-		defer rowsSV.Close()
-		if !rowsSV.Next() {
-			return errors.New("cannot determine schema version: cache file may be corrupt")
-		}
-		if err := rowsSV.Scan(&schemaVersion); err != nil {
-			return err
-		}
-		rowsSV.Close()
-	}
-
-	// Do migrations
-	if schemaVersion == currentSchemaVersion {
-		return nil
-	} else if schemaVersion == 0 {
-		return migrateFrom0(db)
-	} else if schemaVersion == 1 {
-		return migrateFrom1(db)
-	} else if schemaVersion == 2 {
-		return migrateFrom2(db)
-	} else if schemaVersion == 3 {
-		return migrateFrom3(db)
-	} else if schemaVersion == 4 {
-		return migrateFrom4(db)
-	}
-	return fmt.Errorf("unexpected schema version found: %d", schemaVersion)
-}
-
-func setupNewCacheDB(db *sql.DB) error {
-	if _, err := db.Exec(createMessagesTableQuery); err != nil {
-		return err
-	}
-	if _, err := db.Exec(createSchemaVersionTableQuery); err != nil {
-		return err
-	}
-	if _, err := db.Exec(insertSchemaVersion, currentSchemaVersion); err != nil {
-		return err
-	}
-	return nil
-}
-
-func migrateFrom0(db *sql.DB) error {
-	log.Print("Migrating cache database schema: from 0 to 1")
-	if _, err := db.Exec(migrate0To1AlterMessagesTableQuery); err != nil {
-		return err
-	}
-	if _, err := db.Exec(createSchemaVersionTableQuery); err != nil {
-		return err
-	}
-	if _, err := db.Exec(insertSchemaVersion, 1); err != nil {
-		return err
-	}
-	return migrateFrom1(db)
-}
-
-func migrateFrom1(db *sql.DB) error {
-	log.Print("Migrating cache database schema: from 1 to 2")
-	if _, err := db.Exec(migrate1To2AlterMessagesTableQuery); err != nil {
-		return err
-	}
-	if _, err := db.Exec(updateSchemaVersion, 2); err != nil {
-		return err
-	}
-	return migrateFrom2(db)
-}
-
-func migrateFrom2(db *sql.DB) error {
-	log.Print("Migrating cache database schema: from 2 to 3")
-	if _, err := db.Exec(migrate2To3AlterMessagesTableQuery); err != nil {
-		return err
-	}
-	if _, err := db.Exec(updateSchemaVersion, 3); err != nil {
-		return err
-	}
-	return migrateFrom3(db)
-}
-
-func migrateFrom3(db *sql.DB) error {
-	log.Print("Migrating cache database schema: from 3 to 4")
-	if _, err := db.Exec(migrate3To4AlterMessagesTableQuery); err != nil {
-		return err
-	}
-	if _, err := db.Exec(updateSchemaVersion, 4); err != nil {
-		return err
-	}
-	return migrateFrom4(db)
-}
-
-func migrateFrom4(db *sql.DB) error {
-	log.Print("Migrating cache database schema: from 4 to 5")
-	if _, err := db.Exec(migrate4To5AlterMessagesTableQuery); err != nil {
-		return err
-	}
-	if _, err := db.Exec(updateSchemaVersion, 5); err != nil {
-		return err
-	}
-	return nil // Update this when a new version is added
-}
diff --git a/server/cache_sqlite_test.go b/server/cache_sqlite_test.go
index 9c99c6f4..2fb084cd 100644
--- a/server/cache_sqlite_test.go
+++ b/server/cache_sqlite_test.go
@@ -3,6 +3,7 @@ package server
 import (
 	"database/sql"
 	"fmt"
+	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	"path/filepath"
 	"testing"
@@ -13,30 +14,58 @@ func TestSqliteCache_Messages(t *testing.T) {
 	testCacheMessages(t, newSqliteTestCache(t))
 }
 
+func TestMemCache_Messages(t *testing.T) {
+	testCacheMessages(t, newMemTestCache(t))
+}
+
 func TestSqliteCache_MessagesScheduled(t *testing.T) {
 	testCacheMessagesScheduled(t, newSqliteTestCache(t))
 }
 
+func TestMemCache_MessagesScheduled(t *testing.T) {
+	testCacheMessagesScheduled(t, newMemTestCache(t))
+}
+
 func TestSqliteCache_Topics(t *testing.T) {
 	testCacheTopics(t, newSqliteTestCache(t))
 }
 
+func TestMemCache_Topics(t *testing.T) {
+	testCacheTopics(t, newMemTestCache(t))
+}
+
 func TestSqliteCache_MessagesTagsPrioAndTitle(t *testing.T) {
 	testCacheMessagesTagsPrioAndTitle(t, newSqliteTestCache(t))
 }
 
+func TestMemCache_MessagesTagsPrioAndTitle(t *testing.T) {
+	testCacheMessagesTagsPrioAndTitle(t, newMemTestCache(t))
+}
+
 func TestSqliteCache_MessagesSinceID(t *testing.T) {
 	testCacheMessagesSinceID(t, newSqliteTestCache(t))
 }
 
+func TestMemCache_MessagesSinceID(t *testing.T) {
+	testCacheMessagesSinceID(t, newMemTestCache(t))
+}
+
 func TestSqliteCache_Prune(t *testing.T) {
 	testCachePrune(t, newSqliteTestCache(t))
 }
 
+func TestMemCache_Prune(t *testing.T) {
+	testCachePrune(t, newMemTestCache(t))
+}
+
 func TestSqliteCache_Attachments(t *testing.T) {
 	testCacheAttachments(t, newSqliteTestCache(t))
 }
 
+func TestMemCache_Attachments(t *testing.T) {
+	testCacheAttachments(t, newMemTestCache(t))
+}
+
 func TestSqliteCache_Migration_From0(t *testing.T) {
 	filename := newSqliteTestCacheFile(t)
 	db, err := sql.Open("sqlite3", filename)
@@ -141,6 +170,19 @@ func checkSchemaVersion(t *testing.T, db *sql.DB) {
 	require.Nil(t, rows.Close())
 }
 
+func TestMemCache_NopCache(t *testing.T) {
+	c, _ := newNopCache()
+	assert.Nil(t, c.AddMessage(newDefaultMessage("mytopic", "my message")))
+
+	messages, err := c.Messages("mytopic", sinceAllMessages, false)
+	assert.Nil(t, err)
+	assert.Empty(t, messages)
+
+	topics, err := c.Topics()
+	assert.Nil(t, err)
+	assert.Empty(t, topics)
+}
+
 func newSqliteTestCache(t *testing.T) *sqliteCache {
 	c, err := newSqliteCache(newSqliteTestCacheFile(t), false)
 	if err != nil {
@@ -160,3 +202,11 @@ func newSqliteTestCacheFromFile(t *testing.T, filename string) *sqliteCache {
 	}
 	return c
 }
+
+func newMemTestCache(t *testing.T) *sqliteCache {
+	c, err := newMemCache()
+	if err != nil {
+		t.Fatal(err)
+	}
+	return c
+}
diff --git a/server/cache_test.go b/server/cache_test.go
index a80c0552..9c790901 100644
--- a/server/cache_test.go
+++ b/server/cache_test.go
@@ -6,7 +6,7 @@ import (
 	"time"
 )
 
-func testCacheMessages(t *testing.T, c cache) {
+func testCacheMessages(t *testing.T, c *sqliteCache) {
 	m1 := newDefaultMessage("mytopic", "my message")
 	m1.Time = 1
 
@@ -72,7 +72,7 @@ func testCacheMessages(t *testing.T, c cache) {
 	require.Empty(t, messages)
 }
 
-func testCacheTopics(t *testing.T, c cache) {
+func testCacheTopics(t *testing.T, c *sqliteCache) {
 	require.Nil(t, c.AddMessage(newDefaultMessage("topic1", "my example message")))
 	require.Nil(t, c.AddMessage(newDefaultMessage("topic2", "message 1")))
 	require.Nil(t, c.AddMessage(newDefaultMessage("topic2", "message 2")))
@@ -87,7 +87,7 @@ func testCacheTopics(t *testing.T, c cache) {
 	require.Equal(t, "topic2", topics["topic2"].ID)
 }
 
-func testCachePrune(t *testing.T, c cache) {
+func testCachePrune(t *testing.T, c *sqliteCache) {
 	m1 := newDefaultMessage("mytopic", "my message")
 	m1.Time = 1
 
@@ -116,7 +116,7 @@ func testCachePrune(t *testing.T, c cache) {
 	require.Equal(t, "my other message", messages[0].Message)
 }
 
-func testCacheMessagesTagsPrioAndTitle(t *testing.T, c cache) {
+func testCacheMessagesTagsPrioAndTitle(t *testing.T, c *sqliteCache) {
 	m := newDefaultMessage("mytopic", "some message")
 	m.Tags = []string{"tag1", "tag2"}
 	m.Priority = 5
@@ -129,7 +129,7 @@ func testCacheMessagesTagsPrioAndTitle(t *testing.T, c cache) {
 	require.Equal(t, "some title", messages[0].Title)
 }
 
-func testCacheMessagesScheduled(t *testing.T, c cache) {
+func testCacheMessagesScheduled(t *testing.T, c *sqliteCache) {
 	m1 := newDefaultMessage("mytopic", "message 1")
 	m2 := newDefaultMessage("mytopic", "message 2")
 	m2.Time = time.Now().Add(time.Hour).Unix()
@@ -155,7 +155,7 @@ func testCacheMessagesScheduled(t *testing.T, c cache) {
 	require.Empty(t, messages)
 }
 
-func testCacheMessagesSinceID(t *testing.T, c cache) {
+func testCacheMessagesSinceID(t *testing.T, c *sqliteCache) {
 	m1 := newDefaultMessage("mytopic", "message 1")
 	m1.Time = 100
 	m2 := newDefaultMessage("mytopic", "message 2")
@@ -220,7 +220,7 @@ func testCacheMessagesSinceID(t *testing.T, c cache) {
 	// TODO Add more delayed messages
 }
 
-func testCacheAttachments(t *testing.T, c cache) {
+func testCacheAttachments(t *testing.T, c *sqliteCache) {
 	expires1 := time.Now().Add(-4 * time.Hour).Unix()
 	m := newDefaultMessage("mytopic", "flower for you")
 	m.ID = "m1"
diff --git a/server/server.go b/server/server.go
index 4ced5bfb..ef1c30a3 100644
--- a/server/server.go
+++ b/server/server.go
@@ -45,7 +45,7 @@ type Server struct {
 	mailer       mailer
 	messages     int64
 	auth         auth.Auther
-	cache        cache
+	cache        *sqliteCache
 	fileCache    *fileCache
 	closeChan    chan bool
 	mu           sync.Mutex
@@ -160,7 +160,7 @@ func New(conf *Config) (*Server, error) {
 	}, nil
 }
 
-func createCache(conf *Config) (cache, error) {
+func createCache(conf *Config) (*sqliteCache, error) {
 	if conf.CacheDuration == 0 {
 		return newNopCache()
 	} else if conf.CacheFile != "" {