diff --git a/migrations/postgres/2018-12-08-175515_constraints/down.sql b/migrations/postgres/2018-12-08-175515_constraints/down.sql
new file mode 100644
index 00000000..e189dc22
--- /dev/null
+++ b/migrations/postgres/2018-12-08-175515_constraints/down.sql
@@ -0,0 +1,24 @@
+-- This file should undo anything in `up.sql`
+ALTER TABLE api_tokens DROP CONSTRAINT IF EXISTS api_tokens_unique_value;
+ALTER TABLE blog_authors DROP CONSTRAINT IF EXISTS blog_author_unique;
+ALTER TABLE blogs DROP CONSTRAINT IF EXISTS blog_unique;
+ALTER TABLE blogs DROP CONSTRAINT IF EXISTS blog_unique_ap_url;
+ALTER TABLE blogs DROP CONSTRAINT IF EXISTS blog_unique_outbox;
+ALTER TABLE blogs DROP CONSTRAINT IF EXISTS blog_unique_inbox;
+ALTER TABLE comments DROP CONSTRAINT IF EXISTS comments_unique_ap_url;
+ALTER TABLE follows DROP CONSTRAINT IF EXISTS follows_unique_ap_url;
+ALTER TABLE instances DROP CONSTRAINT IF EXISTS instance_unique_domain;
+ALTER TABLE likes DROP CONSTRAINT IF EXISTS likes_unique;
+ALTER TABLE likes DROP CONSTRAINT IF EXISTS likes_unique_ap_url;
+ALTER TABLE mentions DROP CONSTRAINT IF EXISTS mentions_unique_ap_url;
+ALTER TABLE post_authors DROP CONSTRAINT IF EXISTS post_authors_unique;
+ALTER TABLE posts DROP CONSTRAINT IF EXISTS post_unique_slug;
+ALTER TABLE posts DROP CONSTRAINT IF EXISTS post_unique_ap_url;
+ALTER TABLE reshares DROP CONSTRAINT IF EXISTS reshares_unique;
+ALTER TABLE reshares DROP CONSTRAINT IF EXISTS reshares_unique_ap_url;
+ALTER TABLE tags DROP CONSTRAINT IF EXISTS tags_unique;
+ALTER TABLE users DROP CONSTRAINT IF EXISTS users_unique;
+ALTER TABLE users DROP CONSTRAINT IF EXISTS users_unique_inbox;
+ALTER TABLE users DROP CONSTRAINT IF EXISTS users_unique_outbox;
+ALTER TABLE users DROP CONSTRAINT IF EXISTS users_unique_ap_url;
+ALTER TABLE users DROP CONSTRAINT IF EXISTS users_unique_followers_url;
diff --git a/migrations/postgres/2018-12-08-175515_constraints/up.sql b/migrations/postgres/2018-12-08-175515_constraints/up.sql
new file mode 100644
index 00000000..21b6f3b6
--- /dev/null
+++ b/migrations/postgres/2018-12-08-175515_constraints/up.sql
@@ -0,0 +1,83 @@
+-- Your SQL goes here
+
+-- First, we delete the already duplicated data so that the constraint can be correctly applied
+
+DELETE FROM api_tokens a USING api_tokens b WHERE
+	a.id > b.id
+	AND a.value = b.value;
+DELETE FROM blog_authors a USING blog_authors b WHERE
+	a.id > b.id
+	AND a.blog_id = b.blog_id
+	AND a.author_id = b.author_id;
+DELETE FROM blogs a USING blogs b WHERE
+	a.id > b.id
+	AND ((a.actor_id = b.actor_id AND a.instance_id = b.instance_id)
+	OR a.ap_url = b.ap_url
+	OR a.outbox_url = b.outbox_url
+	OR a.inbox_url = b.inbox_url);
+DELETE FROM comments a USING comments b WHERE
+	a.id > b.id
+	AND (a.ap_url = b.ap_url);
+DELETE FROM follows a USING follows b
+	WHERE a.id > b.id
+	AND (a.ap_url = b.ap_url);
+DELETE FROM instances a USING instances b WHERE
+	a.id > b.id
+	AND (a.public_domain = b.public_domain);
+DELETE FROM likes a USING likes b WHERE
+	a.id > b.id
+	AND (a.ap_url = b.ap_url
+	OR (a.user_id = b.user_id AND a.post_id = b.post_id));
+DELETE FROM mentions a USING mentions b WHERE
+	a.id > b.id
+	AND (a.ap_url = b.ap_url);
+DELETE FROM post_authors a USING post_authors b WHERE
+	a.id > b.id
+	AND a.author_id = b.author_id
+	AND a.post_id = b.post_id;
+DELETE FROM posts a USING posts b WHERE
+	a.id > b.id
+	AND ((a.ap_url = b.ap_url)
+	OR (a.blog_id = b.blog_id AND a.slug = b.slug));
+DELETE FROM reshares a USING reshares b WHERE
+	a.id > b.id
+	AND (a.ap_url = b.ap_url
+	OR (a.user_id = b.user_id AND a.post_id = b.post_id));
+DELETE FROM tags a USING tags b WHERE
+	a.id > b.id
+	AND a.tag = b.tag
+	AND a.post_id = b.post_id
+	AND a.is_hashtag = b.is_hashtag;
+DELETE FROM users a USING users b WHERE
+	a.id > b.id
+	AND (a.ap_url = b.ap_url
+	OR (a.username = b.username AND a.instance_id = b.instance_id)
+	OR a.outbox_url = b.outbox_url
+	OR a.inbox_url = b.inbox_url
+	OR a.followers_endpoint = b.followers_endpoint);
+
+-- Then we add the UNIQUE constraints
+
+ALTER TABLE api_tokens ADD CONSTRAINT api_tokens_unique_value UNIQUE (value);
+ALTER TABLE blog_authors ADD CONSTRAINT blog_author_unique UNIQUE (blog_id, author_id);
+ALTER TABLE blogs ADD CONSTRAINT blog_unique UNIQUE (actor_id, instance_id);
+ALTER TABLE blogs ADD CONSTRAINT blog_unique_ap_url UNIQUE (ap_url);
+ALTER TABLE blogs ADD CONSTRAINT blog_unique_outbox UNIQUE (outbox_url);
+ALTER TABLE blogs ADD CONSTRAINT blog_unique_inbox UNIQUE (inbox_url);
+ALTER TABLE comments ADD CONSTRAINT comments_unique_ap_url UNIQUE (ap_url);
+ALTER TABLE follows ADD CONSTRAINT follows_unique_ap_url UNIQUE (ap_url);
+ALTER TABLE instances ADD CONSTRAINT instance_unique_domain UNIQUE (public_domain);
+ALTER TABLE likes ADD CONSTRAINT likes_unique UNIQUE (user_id, post_id);
+ALTER TABLE likes ADD CONSTRAINT likes_unique_ap_url UNIQUE (ap_url);
+ALTER TABLE mentions ADD CONSTRAINT mentions_unique_ap_url UNIQUE (ap_url);
+ALTER TABLE post_authors ADD CONSTRAINT post_authors_unique UNIQUE (post_id, author_id);
+ALTER TABLE posts ADD CONSTRAINT post_unique_slug UNIQUE (blog_id, slug);
+ALTER TABLE posts ADD CONSTRAINT post_unique_ap_url UNIQUE (ap_url);
+ALTER TABLE reshares ADD CONSTRAINT reshares_unique UNIQUE (user_id, post_id);
+ALTER TABLE reshares ADD CONSTRAINT reshares_unique_ap_url UNIQUE (ap_url);
+ALTER TABLE tags ADD CONSTRAINT tags_unique UNIQUE (tag, post_id, is_hashtag);
+ALTER TABLE users ADD CONSTRAINT users_unique UNIQUE (username, instance_id);
+ALTER TABLE users ADD CONSTRAINT users_unique_inbox UNIQUE (inbox_url);
+ALTER TABLE users ADD CONSTRAINT users_unique_outbox UNIQUE (outbox_url);
+ALTER TABLE users ADD CONSTRAINT users_unique_ap_url UNIQUE (ap_url);
+ALTER TABLE users ADD CONSTRAINT users_unique_followers_url UNIQUE (followers_endpoint);
diff --git a/migrations/sqlite/2018-12-08-182930_constraints/down.sql b/migrations/sqlite/2018-12-08-182930_constraints/down.sql
new file mode 100644
index 00000000..5b196d58
--- /dev/null
+++ b/migrations/sqlite/2018-12-08-182930_constraints/down.sql
@@ -0,0 +1,178 @@
+-- This file should undo anything in `up.sql`
+CREATE TABLE api_tokens2 (
+    id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
+    creation_date DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    value TEXT NOT NULL,
+    scopes TEXT NOT NULL,
+    app_id INTEGER NOT NULL REFERENCES apps(id) ON DELETE CASCADE,
+    user_id INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE
+);
+
+INSERT INTO api_tokens2 SELECT * FROM api_tokens;
+DROP TABLE api_tokens;
+ALTER TABLE api_tokens2 RENAME TO api_tokens;
+
+CREATE TABLE blog_authors2 (
+    id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
+    blog_id INTEGER REFERENCES blogs(id) ON DELETE CASCADE NOT NULL,
+    author_id INTEGER REFERENCES users(id) ON DELETE CASCADE NOT NULL,
+    is_owner BOOLEAN NOT NULL DEFAULT 'f'
+);
+
+INSERT INTO blog_authors2 SELECT * FROM blog_authors;
+DROP TABLE blog_authors;
+ALTER TABLE blog_authors2 RENAME TO blog_authors;
+
+CREATE TABLE blogs2 (
+    id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
+    actor_id VARCHAR NOT NULL,
+    title VARCHAR NOT NULL,
+    summary TEXT NOT NULL DEFAULT '',
+    outbox_url VARCHAR NOT NULL,
+    inbox_url VARCHAR NOT NULL,
+    instance_id INTEGER REFERENCES instances(id) ON DELETE CASCADE NOT NULL,
+    creation_date DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    ap_url text not null default '',
+    private_key TEXT,
+    public_key TEXT NOT NULL DEFAULT ''
+)
+
+INSERT INTO blogs2 SELECT * FROM blogs;
+DROP TABLE blogs;
+ALTER TABLE blogs2 RENAME TO blogs;
+
+CREATE TABLE comments2 (
+    id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
+    content TEXT NOT NULL DEFAULT '',
+    in_response_to_id INTEGER REFERENCES comments(id),
+    post_id INTEGER REFERENCES posts(id) ON DELETE CASCADE NOT NULL,
+    author_id INTEGER REFERENCES users(id) ON DELETE CASCADE NOT NULL,
+    creation_date DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    ap_url VARCHAR,
+    sensitive BOOLEAN NOT NULL DEFAULT 'f',
+    spoiler_text TEXT NOT NULL DEFAULT ''
+);
+
+INSERT INTO comments2 SELECT * FROM comments;
+DROP TABLE comments;
+ALTER TABLE comments2 RENAME TO comments;
+
+CREATE TABLE follows2 (
+    id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
+    follower_id INTEGER REFERENCES users(id) ON DELETE CASCADE NOT NULL,
+    following_id INTEGER REFERENCES users(id) ON DELETE CASCADE NOT NULL,
+    ap_url TEXT NOT NULL default ''
+);
+
+INSERT INTO follows2 SELECT * FROM follows;
+DROP TABLE follows;
+ALTER TABLE follows2 RENAME TO follows;
+
+CREATE TABLE instances2 (
+    id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
+    public_domain VARCHAR NOT NULL,
+    name VARCHAR NOT NULL,
+    local BOOLEAN NOT NULL DEFAULT 'f',
+    blocked BOOLEAN NOT NULL DEFAULT 'f',
+    creation_date DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    open_registrations BOOLEAN NOT NULL DEFAULT 't',
+    short_description TEXT NOT NULL DEFAULT '',
+    long_description TEXT NOT NULL DEFAULT '',
+    default_license TEXT NOT NULL DEFAULT 'CC-BY-SA',
+    long_description_html VARCHAR NOT NULL DEFAULT '',
+    short_description_html VARCHAR NOT NULL DEFAULT ''
+);
+
+INSERT INTO instances2 SELECT * FROM instances;
+DROP TABLE instances;
+ALTER TABLE instances2 RENAME TO instances;
+
+CREATE TABLE likes2 (
+    id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
+    user_id INTEGER REFERENCES users(id) ON DELETE CASCADE NOT NULL,
+    post_id INTEGER REFERENCES posts(id) ON DELETE CASCADE NOT NULL,
+    creation_date DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    ap_url VARCHAR NOT NULL default ''
+);
+
+INSERT INTO likes2 SELECT * FROM likes;
+DROP TABLE likes;
+ALTER TABLE likes2 RENAME TO likes;
+
+CREATE TABLE mentions2 (
+    id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
+    mentioned_id INTEGER REFERENCES users(id) ON DELETE CASCADE NOT NULL,
+    post_id INTEGER REFERENCES posts(id) ON DELETE CASCADE,
+    comment_id INTEGER REFERENCES comments(id) ON DELETE CASCADE,
+    ap_url VARCHAR NOT NULL DEFAULT ''
+);
+
+INSERT INTO mentions2 SELECT * FROM mentions;
+DROP TABLE mentions;
+ALTER TABLE mentions2 RENAME TO mentions;
+
+CREATE TABLE post_authors2 (
+    id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
+    post_id INTEGER REFERENCES posts(id) ON DELETE CASCADE NOT NULL,
+    author_id INTEGER REFERENCES users(id) ON DELETE CASCADE NOT NULL
+)
+
+INSERT INTO post_authors2 SELECT * FROM post_authors;
+DROP TABLE post_authors;
+ALTER TABLE post_authors2 RENAME TO post_authors;
+
+CREATE TABLE posts2 (
+    id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
+    blog_id INTEGER REFERENCES blogs(id) ON DELETE CASCADE NOT NULL,
+    slug VARCHAR NOT NULL,
+    title VARCHAR NOT NULL,
+    content TEXT NOT NULL DEFAULT '',
+    published BOOLEAN NOT NULL DEFAULT 'f',
+    license VARCHAR NOT NULL DEFAULT 'CC-BY-SA',
+    creation_date DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    ap_url VARCHAR NOT NULL DEFAULT '',
+    subtitle TEXT NOT NULL DEFAULT '',
+    source TEXT NOT NULL DEFAULT ''
+);
+
+INSERT INTO posts2 SELECT * FROM posts;
+DROP TABLE posts;
+ALTER TABLE posts2 RENAME TO posts;
+
+CREATE TABLE tags2 (
+    id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
+    tag TEXT NOT NULL DEFAULT '',
+    is_hashtag BOOLEAN NOT NULL DEFAULT 'f',
+    post_id INTEGER REFERENCES posts(id) ON DELETE CASCADE NOT NULL
+);
+
+INSERT INTO tags2 SELECT * FROM tags;
+DROP TABLE tags;
+ALTER TABLE tags2 RENAME TO tags;
+
+CREATE TABLE users (
+    id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
+    username VARCHAR NOT NULL,
+    display_name VARCHAR NOT NULL DEFAULT '',
+    outbox_url VARCHAR NOT NULL,
+    inbox_url VARCHAR NOT NULL,
+    is_admin BOOLEAN NOT NULL DEFAULT 'f',
+    summary TEXT NOT NULL DEFAULT '',
+    email TEXT,
+    hashed_password TEXT,
+    instance_id INTEGER REFERENCES instances(id) ON DELETE CASCADE NOT NULL,
+    creation_date DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    ap_url TEXT NOT NULL default '',
+    private_key TEXT,
+    public_key TEXT NOT NULL DEFAULT '',
+    shared_inbox_url VARCHAR,
+    followers_endpoint VARCHAR NOT NULL DEFAULT '',
+    avatar_id INTEGER REFERENCES medias(id) ON DELETE CASCADE,
+    last_fetched_date TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    FOREIGN KEY (avatar_id) REFERENCES medias(id) ON DELETE SET NULL
+);
+
+INSERT INTO users2 SELECT * FROM users;
+DROP TABLE users;
+ALTER TABLE users2 RENAME TO users;
+
diff --git a/migrations/sqlite/2018-12-08-182930_constraints/up.sql b/migrations/sqlite/2018-12-08-182930_constraints/up.sql
new file mode 100644
index 00000000..3b94d401
--- /dev/null
+++ b/migrations/sqlite/2018-12-08-182930_constraints/up.sql
@@ -0,0 +1,186 @@
+-- Your SQL goes here
+CREATE TABLE api_tokens2 (
+    id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
+    creation_date DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    value TEXT NOT NULL UNIQUE,
+    scopes TEXT NOT NULL,
+    app_id INTEGER NOT NULL REFERENCES apps(id) ON DELETE CASCADE,
+    user_id INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE
+);
+
+INSERT INTO api_tokens2 SELECT * FROM api_tokens;
+DROP TABLE api_tokens;
+ALTER TABLE api_tokens2 RENAME TO api_tokens;
+
+CREATE TABLE blog_authors2 (
+    id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
+    blog_id INTEGER REFERENCES blogs(id) ON DELETE CASCADE NOT NULL,
+    author_id INTEGER REFERENCES users(id) ON DELETE CASCADE NOT NULL,
+    is_owner BOOLEAN NOT NULL DEFAULT 'f',
+    CONSTRAINT blog_authors_unique UNIQUE (blog_id, author_id)
+);
+
+INSERT INTO blog_authors2 SELECT * FROM blog_authors;
+DROP TABLE blog_authors;
+ALTER TABLE blog_authors2 RENAME TO blog_authors;
+
+CREATE TABLE blogs2 (
+    id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
+    actor_id VARCHAR NOT NULL,
+    title VARCHAR NOT NULL,
+    summary TEXT NOT NULL DEFAULT '',
+    outbox_url VARCHAR NOT NULL UNIQUE,
+    inbox_url VARCHAR NOT NULL UNIQUE,
+    instance_id INTEGER REFERENCES instances(id) ON DELETE CASCADE NOT NULL,
+    creation_date DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    ap_url text not null default '' UNIQUE,
+    private_key TEXT,
+    public_key TEXT NOT NULL DEFAULT '',
+    CONSTRAINT blog_unique UNIQUE (actor_id, instance_id)
+);
+
+INSERT INTO blogs2 SELECT * FROM blogs;
+DROP TABLE blogs;
+ALTER TABLE blogs2 RENAME TO blogs;
+
+CREATE TABLE comments2 (
+    id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
+    content TEXT NOT NULL DEFAULT '',
+    in_response_to_id INTEGER REFERENCES comments(id),
+    post_id INTEGER REFERENCES posts(id) ON DELETE CASCADE NOT NULL,
+    author_id INTEGER REFERENCES users(id) ON DELETE CASCADE NOT NULL,
+    creation_date DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    ap_url VARCHAR UNIQUE,
+    sensitive BOOLEAN NOT NULL DEFAULT 'f',
+    spoiler_text TEXT NOT NULL DEFAULT ''
+);
+
+INSERT INTO comments2 SELECT * FROM comments;
+DROP TABLE comments;
+ALTER TABLE comments2 RENAME TO comments;
+
+CREATE TABLE follows2 (
+    id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
+    follower_id INTEGER REFERENCES users(id) ON DELETE CASCADE NOT NULL,
+    following_id INTEGER REFERENCES users(id) ON DELETE CASCADE NOT NULL,
+    ap_url TEXT NOT NULL default '' UNIQUE
+);
+
+INSERT INTO follows2 SELECT * FROM follows;
+DROP TABLE follows;
+ALTER TABLE follows2 RENAME TO follows;
+
+CREATE TABLE instances2 (
+    id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
+    public_domain VARCHAR NOT NULL UNIQUE,
+    name VARCHAR NOT NULL,
+    local BOOLEAN NOT NULL DEFAULT 'f',
+    blocked BOOLEAN NOT NULL DEFAULT 'f',
+    creation_date DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    open_registrations BOOLEAN NOT NULL DEFAULT 't',
+    short_description TEXT NOT NULL DEFAULT '',
+    long_description TEXT NOT NULL DEFAULT '',
+    default_license TEXT NOT NULL DEFAULT 'CC-BY-SA',
+    long_description_html VARCHAR NOT NULL DEFAULT '',
+    short_description_html VARCHAR NOT NULL DEFAULT ''
+);
+
+INSERT INTO instances2 SELECT * FROM instances;
+DROP TABLE instances;
+ALTER TABLE instances2 RENAME TO instances;
+
+CREATE TABLE likes2 (
+    id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
+    user_id INTEGER REFERENCES users(id) ON DELETE CASCADE NOT NULL,
+    post_id INTEGER REFERENCES posts(id) ON DELETE CASCADE NOT NULL,
+    creation_date DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    ap_url VARCHAR NOT NULL default '' UNIQUE,
+    CONSTRAINT likes_unique UNIQUE (user_id, post_id)
+);
+
+INSERT INTO likes2 SELECT * FROM likes;
+DROP TABLE likes;
+ALTER TABLE likes2 RENAME TO likes;
+
+CREATE TABLE mentions2 (
+    id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
+    mentioned_id INTEGER REFERENCES users(id) ON DELETE CASCADE NOT NULL,
+    post_id INTEGER REFERENCES posts(id) ON DELETE CASCADE,
+    comment_id INTEGER REFERENCES comments(id) ON DELETE CASCADE,
+    ap_url VARCHAR NOT NULL DEFAULT '' UNIQUE
+);
+
+INSERT INTO mentions2 SELECT * FROM mentions;
+DROP TABLE mentions;
+ALTER TABLE mentions2 RENAME TO mentions;
+
+CREATE TABLE post_authors2 (
+    id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
+    post_id INTEGER REFERENCES posts(id) ON DELETE CASCADE NOT NULL,
+    author_id INTEGER REFERENCES users(id) ON DELETE CASCADE NOT NULL,
+    CONSTRAINT blog_authors_unique UNIQUE (post_id, author_id)
+);
+
+INSERT INTO post_authors2 SELECT * FROM post_authors;
+DROP TABLE post_authors;
+ALTER TABLE post_authors2 RENAME TO post_authors;
+
+CREATE TABLE posts2 (
+    id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
+    blog_id INTEGER REFERENCES blogs(id) ON DELETE CASCADE NOT NULL,
+    slug VARCHAR NOT NULL,
+    title VARCHAR NOT NULL,
+    content TEXT NOT NULL DEFAULT '',
+    published BOOLEAN NOT NULL DEFAULT 'f',
+    license VARCHAR NOT NULL DEFAULT 'CC-BY-SA',
+    creation_date DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    ap_url VARCHAR NOT NULL DEFAULT '' UNIQUE,
+    subtitle TEXT NOT NULL DEFAULT '',
+    source TEXT NOT NULL DEFAULT '',
+    cover_id INTEGER REFERENCES medias(id) DEFAULT NULL,
+    CONSTRAINT blog_authors_unique UNIQUE (blog_id, slug)
+);
+
+INSERT INTO posts2 SELECT * FROM posts;
+DROP TABLE posts;
+ALTER TABLE posts2 RENAME TO posts;
+
+CREATE TABLE tags2 (
+    id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
+    tag TEXT NOT NULL DEFAULT '',
+    is_hashtag BOOLEAN NOT NULL DEFAULT 'f',
+    post_id INTEGER REFERENCES posts(id) ON DELETE CASCADE NOT NULL,
+    CONSTRAINT blog_authors_unique UNIQUE (tag, is_hashtag, post_id)
+);
+
+INSERT INTO tags2 SELECT * FROM tags;
+DROP TABLE tags;
+ALTER TABLE tags2 RENAME TO tags;
+
+CREATE TABLE users2 (
+    id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
+    username VARCHAR NOT NULL,
+    display_name VARCHAR NOT NULL DEFAULT '',
+    outbox_url VARCHAR NOT NULL UNIQUE,
+    inbox_url VARCHAR NOT NULL UNIQUE,
+    is_admin BOOLEAN NOT NULL DEFAULT 'f',
+    summary TEXT NOT NULL DEFAULT '',
+    email TEXT,
+    hashed_password TEXT,
+    instance_id INTEGER REFERENCES instances(id) ON DELETE CASCADE NOT NULL,
+    creation_date DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    ap_url TEXT NOT NULL default '' UNIQUE,
+    private_key TEXT,
+    public_key TEXT NOT NULL DEFAULT '',
+    shared_inbox_url VARCHAR,
+    followers_endpoint VARCHAR NOT NULL DEFAULT '' UNIQUE,
+    avatar_id INTEGER REFERENCES medias(id) ON DELETE CASCADE,
+    last_fetched_date TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    FOREIGN KEY (avatar_id) REFERENCES medias(id) ON DELETE SET NULL,
+    CONSTRAINT blog_authors_unique UNIQUE (username, instance_id)
+);
+
+INSERT INTO users2 SELECT * FROM users;
+DROP TABLE users;
+ALTER TABLE users2 RENAME TO users;
+
diff --git a/plume-models/src/blogs.rs b/plume-models/src/blogs.rs
index 318eb529..55292351 100644
--- a/plume-models/src/blogs.rs
+++ b/plume-models/src/blogs.rs
@@ -513,36 +513,35 @@ pub(crate) mod tests {
     use search::tests::get_searcher;
     use Connection as Conn;
 
-    pub(crate) fn fill_database(conn: &Conn) -> Vec<Blog> {
+    pub(crate) fn fill_database(conn: &Conn) -> (Vec<User>, Vec<Blog>) {
         instance_tests::fill_database(conn);
         let users = usersTests::fill_database(conn);
-        let blogs = vec![
-            NewBlog::new_local(
-                "BlogName".to_owned(),
-                "Blog name".to_owned(),
-                "This is a small blog".to_owned(),
-                Instance::local_id(conn),
-            ),
-            NewBlog::new_local(
+        let blog1 = Blog::insert(conn, NewBlog::new_local(
+            "BlogName".to_owned(),
+            "Blog name".to_owned(),
+            "This is a small blog".to_owned(),
+            Instance::local_id(conn),
+        ));
+        blog1.update_boxes(conn);
+        let blog2 = Blog::insert(conn, NewBlog::new_local(
                 "MyBlog".to_owned(),
                 "My blog".to_owned(),
                 "Welcome to my blog".to_owned(),
                 Instance::local_id(conn),
-            ),
-            NewBlog::new_local(
+        ));
+        blog2.update_boxes(conn);
+        let blog3 = Blog::insert(conn, NewBlog::new_local(
                 "WhyILikePlume".to_owned(),
                 "Why I like Plume".to_owned(),
                 "In this blog I will explay you why I like Plume so much".to_owned(),
                 Instance::local_id(conn),
-            ),
-        ].into_iter()
-            .map(|nb| Blog::insert(conn, nb))
-            .collect::<Vec<_>>();
+        ));
+        blog3.update_boxes(conn);
 
         BlogAuthor::insert(
             conn,
             NewBlogAuthor {
-                blog_id: blogs[0].id,
+                blog_id: blog1.id,
                 author_id: users[0].id,
                 is_owner: true,
             },
@@ -551,7 +550,7 @@ pub(crate) mod tests {
         BlogAuthor::insert(
             conn,
             NewBlogAuthor {
-                blog_id: blogs[0].id,
+                blog_id: blog1.id,
                 author_id: users[1].id,
                 is_owner: false,
             },
@@ -560,7 +559,7 @@ pub(crate) mod tests {
         BlogAuthor::insert(
             conn,
             NewBlogAuthor {
-                blog_id: blogs[1].id,
+                blog_id: blog2.id,
                 author_id: users[1].id,
                 is_owner: true,
             },
@@ -569,12 +568,12 @@ pub(crate) mod tests {
         BlogAuthor::insert(
             conn,
             NewBlogAuthor {
-                blog_id: blogs[2].id,
+                blog_id: blog3.id,
                 author_id: users[2].id,
                 is_owner: true,
             },
         );
-        blogs
+        (users, vec![ blog1, blog2, blog3 ])
     }
 
     #[test]
@@ -604,29 +603,29 @@ pub(crate) mod tests {
     fn authors() {
         let conn = &db();
         conn.test_transaction::<_, (), _>(|| {
-            let user = usersTests::fill_database(conn);
-            fill_database(conn);
+            let (user, _) = fill_database(conn);
 
-            let blog = vec![
-                Blog::insert(
-                    conn,
-                    NewBlog::new_local(
-                        "SomeName".to_owned(),
-                        "Some name".to_owned(),
-                        "This is some blog".to_owned(),
-                        Instance::local_id(conn),
-                    ),
+            let b1 = Blog::insert(
+                conn,
+                NewBlog::new_local(
+                    "SomeName".to_owned(),
+                    "Some name".to_owned(),
+                    "This is some blog".to_owned(),
+                    Instance::local_id(conn),
                 ),
-                Blog::insert(
-                    conn,
-                    NewBlog::new_local(
-                        "Blog".to_owned(),
-                        "Blog".to_owned(),
-                        "I've named my blog Blog".to_owned(),
-                        Instance::local_id(conn),
-                    ),
+            );
+            b1.update_boxes(conn);
+            let b2 = Blog::insert(
+                conn,
+                NewBlog::new_local(
+                    "Blog".to_owned(),
+                    "Blog".to_owned(),
+                    "I've named my blog Blog".to_owned(),
+                    Instance::local_id(conn),
                 ),
-            ];
+            );
+            b2.update_boxes(conn);
+            let blog = vec![ b1, b2 ];
 
             BlogAuthor::insert(
                 conn,
@@ -756,7 +755,7 @@ pub(crate) mod tests {
     fn delete() {
         let conn = &db();
         conn.test_transaction::<_, (), _>(|| {
-            let blogs = fill_database(conn);
+            let (_, blogs) = fill_database(conn);
 
             blogs[0].delete(conn, &get_searcher());
             assert!(Blog::get(conn, blogs[0].id).is_none());
@@ -770,29 +769,29 @@ pub(crate) mod tests {
         let conn = &db();
         conn.test_transaction::<_, (), _>(|| {
             let searcher = get_searcher();
-            let user = usersTests::fill_database(conn);
-            fill_database(conn);
+            let (user, _) = fill_database(conn);
 
-            let blog = vec![
-                Blog::insert(
-                    conn,
-                    NewBlog::new_local(
-                        "SomeName".to_owned(),
-                        "Some name".to_owned(),
-                        "This is some blog".to_owned(),
-                        Instance::local_id(conn),
-                    ),
+            let b1 = Blog::insert(
+                conn,
+                NewBlog::new_local(
+                    "SomeName".to_owned(),
+                    "Some name".to_owned(),
+                    "This is some blog".to_owned(),
+                    Instance::local_id(conn),
                 ),
-                Blog::insert(
-                    conn,
-                    NewBlog::new_local(
-                        "Blog".to_owned(),
-                        "Blog".to_owned(),
-                        "I've named my blog Blog".to_owned(),
-                        Instance::local_id(conn),
-                    ),
+            );
+            b1.update_boxes(conn);
+            let b2 = Blog::insert(
+                conn,
+                NewBlog::new_local(
+                    "Blog".to_owned(),
+                    "Blog".to_owned(),
+                    "I've named my blog Blog".to_owned(),
+                    Instance::local_id(conn),
                 ),
-            ];
+            );
+            b2.update_boxes(conn);
+            let blog = vec![ b1, b2 ];
 
             BlogAuthor::insert(
                 conn,
diff --git a/plume-models/src/medias.rs b/plume-models/src/medias.rs
index bb3c4e81..ccf6516c 100644
--- a/plume-models/src/medias.rs
+++ b/plume-models/src/medias.rs
@@ -220,7 +220,7 @@ pub(crate) mod tests {
     use users::tests as usersTests;
     use Connection as Conn;
 
-    pub(crate) fn fill_database(conn: &Conn) -> Vec<Media> {
+    pub(crate) fn fill_database(conn: &Conn) -> (Vec<User>, Vec<Media>) {
         let mut wd = current_dir().unwrap().to_path_buf();
         while wd.pop() {
             if wd.join(".git").exists() {
@@ -236,7 +236,7 @@ pub(crate) mod tests {
         let f2 = "static/media/2.mp3".to_owned();
         fs::write(f1.clone(), []).unwrap();
         fs::write(f2.clone(), []).unwrap();
-        vec![
+        (users, vec![
             NewMedia {
                 file_path: f1,
                 alt_text: "some alt".to_owned(),
@@ -266,7 +266,7 @@ pub(crate) mod tests {
             },
         ].into_iter()
             .map(|nm| Media::insert(conn, nm))
-            .collect()
+            .collect())
     }
 
     pub(crate) fn clean(conn: &Conn) {
@@ -282,8 +282,7 @@ pub(crate) mod tests {
     fn delete() {
         let conn = &db();
         conn.test_transaction::<_, (), _>(|| {
-            let user = usersTests::fill_database(conn)[0].id;
-            fill_database(conn);
+            let user = fill_database(conn).0[0].id;
 
             let path = "static/media/test_deletion".to_owned();
             fs::write(path.clone(), []).unwrap();
@@ -316,10 +315,9 @@ pub(crate) mod tests {
     fn set_owner() {
         let conn = &db();
         conn.test_transaction::<_, (), _>(|| {
-            let users = usersTests::fill_database(conn);
+            let (users, _) = fill_database(conn);
             let u1 = &users[0];
             let u2 = &users[1];
-            fill_database(conn);
 
             let path = "static/media/test_set_owner".to_owned();
             fs::write(path.clone(), []).unwrap();
diff --git a/plume-models/src/search/mod.rs b/plume-models/src/search/mod.rs
index 35776ae8..30c08fc6 100644
--- a/plume-models/src/search/mod.rs
+++ b/plume-models/src/search/mod.rs
@@ -117,7 +117,7 @@ pub(crate) mod tests {
         let conn = &db();
         conn.test_transaction::<_, (), _>(|| {
             let searcher = get_searcher();
-            let blog = &fill_database(conn)[0];
+            let blog = &fill_database(conn).1[0];
             let author = &blog.list_authors(conn)[0];
 
             let title = random_hex()[..8].to_owned();
diff --git a/plume-models/src/users.rs b/plume-models/src/users.rs
index 92b279bf..1187ec79 100644
--- a/plume-models/src/users.rs
+++ b/plume-models/src/users.rs
@@ -998,39 +998,37 @@ pub(crate) mod tests {
 
     pub(crate) fn fill_database(conn: &Conn) -> Vec<User> {
         instance_tests::fill_database(conn);
-        let local_user = vec![
-            NewUser::new_local(
-                conn,
-                "admin".to_owned(),
-                "The admin".to_owned(),
-                true,
-                "Hello there, I'm the admin",
-                "admin@example.com".to_owned(),
-                "invalid_admin_password".to_owned(),
-            ),
-            NewUser::new_local(
-                conn,
-                "user".to_owned(),
-                "Some user".to_owned(),
-                false,
-                "Hello there, I'm no one",
-                "user@example.com".to_owned(),
-                "invalid_user_password".to_owned(),
-            ),
-            NewUser::new_local(
-                conn,
-                "other".to_owned(),
-                "Another user".to_owned(),
-                false,
-                "Hello there, I'm someone else",
-                "other@example.com".to_owned(),
-                "invalid_other_password".to_owned(),
-            ),
-        ];
-        for u in local_user.iter() {
-            u.update_boxes(conn);
-        }
-        local_user
+        let admin = NewUser::new_local(
+            conn,
+            "admin".to_owned(),
+            "The admin".to_owned(),
+            true,
+            "Hello there, I'm the admin",
+            "admin@example.com".to_owned(),
+            "invalid_admin_password".to_owned(),
+        );
+        admin.update_boxes(conn);
+        let user = NewUser::new_local(
+            conn,
+            "user".to_owned(),
+            "Some user".to_owned(),
+            false,
+            "Hello there, I'm no one",
+            "user@example.com".to_owned(),
+            "invalid_user_password".to_owned(),
+        );
+        user.update_boxes(conn);
+        let other = NewUser::new_local(
+            conn,
+            "other".to_owned(),
+            "Another user".to_owned(),
+            false,
+            "Hello there, I'm someone else",
+            "other@example.com".to_owned(),
+            "invalid_other_password".to_owned(),
+        );
+        other.update_boxes(conn);
+        vec![ admin, user, other ]
     }
 
     #[test]