--- a/sat/memory/memory.py	Fri Jun 25 10:17:34 2021 +0200
+++ b/sat/memory/memory.py	Fri Jun 25 17:55:23 2021 +0200
@@ -223,7 +223,7 @@
         )
 
 
-class Memory(object):
+class Memory:
     """This class manage all the persistent information"""
 
     def __init__(self, host):
@@ -241,10 +241,7 @@
         self._cache_path = Path(self.getConfig("", "local_dir"), C.CACHE_DIR)
 
     async def initialise(self):
-        database_file = os.path.expanduser(
-            os.path.join(self.getConfig("", "local_dir"), C.SAVEFILE_DATABASE)
-        )
-        self.storage = Storage(database_file, self.host.version)
+        self.storage = Storage()
         await self.storage.initialise()
         PersistentDict.storage = self.storage
         self.params = Params(self.host, self.storage)

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/sat/memory/migration/README	Fri Jun 25 17:55:23 2021 +0200
@@ -0,0 +1,3 @@
+This directory and subdirectories contains Alembic migration scripts.
+
+Please check Libervia documentation for details.

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/sat/memory/migration/alembic.ini	Fri Jun 25 17:55:23 2021 +0200
@@ -0,0 +1,89 @@
+# A generic, single database configuration.
+
+[alembic]
+# path to migration scripts
+script_location = %(here)s
+
+# template used to generate migration files
+# file_template = %%(rev)s_%%(slug)s
+
+# sys.path path, will be prepended to sys.path if present.
+# defaults to the current working directory.
+# prepend_sys_path = .
+
+# timezone to use when rendering the date
+# within the migration file as well as the filename.
+# string value is passed to dateutil.tz.gettz()
+# leave blank for localtime
+# timezone =
+
+# max length of characters to apply to the
+# "slug" field
+# truncate_slug_length = 40
+
+# set to 'true' to run the environment during
+# the 'revision' command, regardless of autogenerate
+# revision_environment = false
+
+# set to 'true' to allow .pyc and .pyo files without
+# a source .py file to be detected as revisions in the
+# versions/ directory
+# sourceless = false
+
+# version location specification; this defaults
+# to migration/versions.  When using multiple version
+# directories, initial revisions must be specified with --version-path
+# version_locations = %(here)s/bar %(here)s/bat migration/versions
+
+# the output encoding used when revision files
+# are written from script.py.mako
+# output_encoding = utf-8
+
+# sqlalchemy.url = driver://user:pass@localhost/dbname
+
+
+[post_write_hooks]
+# post_write_hooks defines scripts or Python functions that are run
+# on newly generated revision scripts.  See the documentation for further
+# detail and examples
+
+# format using "black" - use the console_scripts runner, against the "black" entrypoint
+# hooks = black
+# black.type = console_scripts
+# black.entrypoint = black
+# black.options = -l 79 REVISION_SCRIPT_FILENAME
+
+# Logging configuration
+[loggers]
+keys = root,sqlalchemy,alembic
+
+[handlers]
+keys = console
+
+[formatters]
+keys = generic
+
+[logger_root]
+level = WARN
+handlers = console
+qualname =
+
+[logger_sqlalchemy]
+level = WARN
+handlers =
+qualname = sqlalchemy.engine
+
+[logger_alembic]
+level = INFO
+handlers =
+qualname = alembic
+
+[handler_console]
+class = StreamHandler
+args = (sys.stderr,)
+level = NOTSET
+formatter = generic
+
+[formatter_generic]
+format = %(levelname)-5.5s [%(name)s] %(message)s
+datefmt = %H:%M:%S

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/sat/memory/migration/env.py	Fri Jun 25 17:55:23 2021 +0200
@@ -0,0 +1,85 @@
+import asyncio
+from logging.config import fileConfig
+from sqlalchemy import pool
+from sqlalchemy.ext.asyncio import create_async_engine
+from alembic import context
+from sat.memory import sqla_config
+from sat.memory.sqla_mapping import Base
+
+# this is the Alembic Config object, which provides
+# access to the values within the .ini file in use.
+config = context.config
+
+# Interpret the config file for Python logging.
+# This line sets up loggers basically.
+fileConfig(config.config_file_name)
+
+# add your model's MetaData object here
+# for 'autogenerate' support
+# from myapp import mymodel
+# target_metadata = mymodel.Base.metadata
+target_metadata = Base.metadata
+
+# other values from the config, defined by the needs of env.py,
+# can be acquired:
+# my_important_option = config.get_main_option("my_important_option")
+# ... etc.
+
+
+def run_migrations_offline():
+    """Run migrations in 'offline' mode.
+
+    This configures the context with just a URL
+    and not an Engine, though an Engine is acceptable
+    here as well.  By skipping the Engine creation
+    we don't even need a DBAPI to be available.
+
+    Calls to context.execute() here emit the given string to the
+    script output.
+
+    """
+    db_config = sqla_config.getDbConfig()
+    context.configure(
+        url=db_config["url"],
+        target_metadata=target_metadata,
+        literal_binds=True,
+        dialect_opts={"paramstyle": "named"},
+    )
+
+    with context.begin_transaction():
+        context.run_migrations()
+
+
+def do_run_migrations(connection):
+    context.configure(
+        connection=connection,
+        target_metadata=target_metadata,
+        render_as_batch=True
+    )
+
+    with context.begin_transaction():
+        context.run_migrations()
+
+
+async def run_migrations_online():
+    """Run migrations in 'online' mode.
+
+    In this scenario we need to create an Engine
+    and associate a connection with the context.
+
+    """
+    db_config = sqla_config.getDbConfig()
+    engine = create_async_engine(
+        db_config["url"],
+        poolclass=pool.NullPool,
+        future=True,
+    )
+
+    async with engine.connect() as connection:
+        await connection.run_sync(do_run_migrations)
+
+
+if context.is_offline_mode():
+    run_migrations_offline()
+else:
+    asyncio.run(run_migrations_online())

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/sat/memory/migration/script.py.mako	Fri Jun 25 17:55:23 2021 +0200
@@ -0,0 +1,24 @@
+"""${message}
+
+Revision ID: ${up_revision}
+Revises: ${down_revision | comma,n}
+Create Date: ${create_date}
+
+"""
+from alembic import op
+import sqlalchemy as sa
+${imports if imports else ""}
+
+# revision identifiers, used by Alembic.
+revision = ${repr(up_revision)}
+down_revision = ${repr(down_revision)}
+branch_labels = ${repr(branch_labels)}
+depends_on = ${repr(depends_on)}
+
+
+def upgrade():
+    ${upgrades if upgrades else "pass"}
+
+
+def downgrade():
+    ${downgrades if downgrades else "pass"}

--- a/sat/memory/sqla.py	Fri Jun 25 10:17:34 2021 +0200
+++ b/sat/memory/sqla.py	Fri Jun 25 17:55:23 2021 +0200
@@ -16,18 +16,22 @@
 # You should have received a copy of the GNU Affero General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+import sys
 import time
+import asyncio
+from asyncio.subprocess import PIPE
+from pathlib import Path
 from typing import Dict, List, Tuple, Iterable, Any, Callable, Optional
-from urllib.parse import quote
-from pathlib import Path
-from sqlalchemy.ext.asyncio import AsyncSession, create_async_engine
+from sqlalchemy.ext.asyncio import AsyncSession, AsyncEngine, create_async_engine
 from sqlalchemy.exc import IntegrityError, NoResultFound
 from sqlalchemy.orm import sessionmaker, subqueryload, contains_eager
 from sqlalchemy.future import select
-from sqlalchemy.engine import Engine
+from sqlalchemy.engine import Engine, Connection
 from sqlalchemy import update, delete, and_, or_, event
 from sqlalchemy.sql.functions import coalesce, sum as sum_
 from sqlalchemy.dialects.sqlite import insert
+from alembic import script as al_script, config as al_config
+from alembic.runtime import migration as al_migration
 from twisted.internet import defer
 from twisted.words.protocols.jabber import jid
 from sat.core.i18n import _
@@ -36,6 +40,8 @@
 from sat.core.constants import Const as C
 from sat.core.core_types import SatXMPPEntity
 from sat.tools.utils import aio
+from sat.memory import migration
+from sat.memory import sqla_config
 from sat.memory.sqla_mapping import (
     NOT_IN_EXTRA,
     Base,
@@ -56,6 +62,7 @@
 
 
 log = getLogger(__name__)
+migration_path = Path(migration.__file__).parent
 
 
 @event.listens_for(Engine, "connect")
@@ -67,32 +74,95 @@
 
 class Storage:
 
-    def __init__(self, db_filename, sat_version):
+    def __init__(self):
         self.initialized = defer.Deferred()
-        self.filename = Path(db_filename)
         # we keep cache for the profiles (key: profile name, value: profile id)
         # profile id to name
         self.profiles: Dict[int, str] = {}
         # profile id to component entry point
         self.components: Dict[int, str] = {}
 
+    async def migrateApply(self, *args: str, log_output: bool = False) -> None:
+        """Do a migration command
+
+        Commands are applied by running Alembic in a subprocess.
+        Arguments are alembic executables commands
+
+        @param log_output: manage stdout and stderr:
+            - if False, stdout and stderr are buffered, and logged only in case of error
+            - if True, stdout and stderr will be logged during the command execution
+        @raise exceptions.DatabaseError: something went wrong while running the
+            process
+        """
+        stdout, stderr = 2 * (None,) if log_output else 2 * (PIPE,)
+        proc = await asyncio.create_subprocess_exec(
+            sys.executable, "-m", "alembic", *args,
+            stdout=stdout, stderr=stderr, cwd=migration_path
+        )
+        log_out, log_err = await proc.communicate()
+        if proc.returncode != 0:
+            msg = _(
+                "Can't {operation} database (exit code {exit_code})"
+            ).format(
+                operation=args[0],
+                exit_code=proc.returncode
+            )
+            if log_out or log_err:
+                msg += f":\nstdout: {log_out.decode()}\nstderr: {log_err.decode()}"
+            log.error(msg)
+
+            raise exceptions.DatabaseError(msg)
+
+    async def createDB(self, engine: AsyncEngine, db_config: dict) -> None:
+        """Create a new database
+
+        The database is generated from SQLAlchemy model, then stamped by Alembic
+        """
+        # the dir may not exist if it's not the XDG recommended one
+        db_config["path"].parent.mkdir(0o700, True, True)
+        async with engine.begin() as conn:
+            await conn.run_sync(Base.metadata.create_all)
+
+        log.debug("stamping the database")
+        await self.migrateApply("stamp", "head")
+        log.debug("stamping done")
+
+    def _checkDBIsUpToDate(self, conn: Connection) -> bool:
+        al_ini_path = migration_path / "alembic.ini"
+        al_cfg = al_config.Config(al_ini_path)
+        directory = al_script.ScriptDirectory.from_config(al_cfg)
+        context = al_migration.MigrationContext.configure(conn)
+        return set(context.get_current_heads()) == set(directory.get_heads())
+
+    async def checkAndUpdateDB(self, engine: AsyncEngine, db_config: dict) -> None:
+        """Check that database is up-to-date, and update if necessary"""
+        async with engine.connect() as conn:
+            up_to_date = await conn.run_sync(self._checkDBIsUpToDate)
+        if up_to_date:
+            log.debug("Database is up-to-date")
+        else:
+            log.info("Database needs to be updated")
+            log.info("updating…")
+            await self.migrateApply("upgrade", "head", log_output=True)
+            log.info("Database is now up-to-date")
+
     @aio
-    async def initialise(self):
+    async def initialise(self) -> None:
         log.info(_("Connecting database"))
+        db_config = sqla_config.getDbConfig()
         engine = create_async_engine(
-            f"sqlite+aiosqlite:///{quote(str(self.filename))}",
+            db_config["url"],
             future=True
         )
         self.session = sessionmaker(
             engine, expire_on_commit=False, class_=AsyncSession
         )
-        new_base = not self.filename.exists()
+        new_base = not db_config["path"].exists()
         if new_base:
             log.info(_("The database is new, creating the tables"))
-            # the dir may not exist if it's not the XDG recommended one
-            self.filename.parent.mkdir(0o700, True, True)
-            async with engine.begin() as conn:
-                await conn.run_sync(Base.metadata.create_all)
+            await self.createDB(engine, db_config)
+        else:
+            await self.checkAndUpdateDB(engine, db_config)
 
         async with self.session() as session:
             result = await session.execute(select(Profile))

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/sat/memory/sqla_config.py	Fri Jun 25 17:55:23 2021 +0200
@@ -0,0 +1,40 @@
+#!/usr/bin/env python3
+
+# Libervia: an XMPP client
+# Copyright (C) 2009-2021 Jérôme Poisson (goffi@goffi.org)
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+from pathlib import Path
+from urllib.parse import quote
+from sat.core.constants import Const as C
+from sat.tools import config
+
+
+def getDbConfig() -> dict:
+    """Get configuration for database
+
+    @return: dict with following keys:
+        - type: only "sqlite" for now
+        - path: path to the sqlite DB
+    """
+    main_conf = config.parseMainConf()
+    local_dir = Path(config.getConfig(main_conf, "", "local_dir"))
+    database_path = (local_dir / C.SAVEFILE_DATABASE).expanduser()
+    url = f"sqlite+aiosqlite:///{quote(str(database_path))}"
+    return {
+        "type": "sqlite",
+        "path": database_path,
+        "url": url,
+    }

--- a/setup.py	Fri Jun 25 10:17:34 2021 +0200
+++ b/setup.py	Fri Jun 25 17:55:23 2021 +0200
@@ -55,8 +55,9 @@
     'omemo-backend-signal < 0.3',
     'pyyaml < 5.5.0',
     'sqlalchemy >= 1.4',
+    'alembic',
     'aiosqlite',
-    'txdbus'
+    'txdbus',
 ]
 
 extras_require = {
@@ -140,6 +141,6 @@
     use_scm_version=sat_dev_version if is_dev_version else False,
     install_requires=install_requires,
     extras_require=extras_require,
-    package_data={"sat": ["VERSION"]},
+    package_data={"sat": ["VERSION", "memory/migration/alembic.ini"]},
     python_requires=">=3.7",
-)
\ No newline at end of file
+)