Need help with migratus?
Click the “chat” button below for chat support from the developer who created it, or find similar developers for support.

About the developer

514 Stars 82 Forks 338 Commits 17 Opened issues



Services available


Need anything else?

Contributors list




A general migration framework, with implementations for migrations as SQL scripts or general Clojure code.

Designed to be compatible with a git based work flow where multiple topic branches may exist simultaneously, and be merged into a master branch in unpredictable order.

This is accomplished two ways:

  1. Migration ids are not assumed to be incremented integers. It is recommended that they be timestamps (e.g. '20111202091200').
  2. Migrations are considered for completion independently.

Using a 14 digit timestamp will accommodate migrations granularity to a second, reducing the chance of collisions for a distributed team.

In contrast, using a single global version for a store and incremented integers for migration versions, it is possible for a higher numbered migration to get merged to master and deployed before a lower numbered migration, in which case the lower numbered migration would never get run, unless it is renumbered.

Migratus does not use a single global version for a store. It considers each migration independently, and runs all uncompleted migrations in sorted order.

Quick Start

  • add the Migratus dependency:

Clojars Project Open Source Helpers

  • Add the following code to

  • Add the following code to


Multiple Statements

If you would like to run multiple statements in your migration, then separate them with

. For example:
CREATE TABLE IF NOT EXISTS quux(id bigint, name varchar(255));
CREATE INDEX quux_name on quux(name);

This is necessary because JDBC does not have a method that allows you to send multiple SQL commands for execution. Migratus will split your commands, and attempt to execute them inside of a transaction.

Note that some databases, such as MySQL, do not support transactional DDL commands. If you're working with such a database then it will not be able to rollback all the DDL statements that were applied in case a statement fails.

Disabling transactions

Migratus attempts to run migrations within a transaction by default. However, some databases do not support transactional DDL statements. Transactions can be disabled by adding the following line at the start of the migration file:

-- :disable-transaction

Running Functions in Migrations

Functions inside migrations may need to be additionally wrapped, a PostgreSQL example would look as follows:

DO $func$
 PERFORM schema_name.function_name('foo', 10);


To run migrations against several different databases (in MySQL, or "schemas" in Postgres, etc.), with embedded

statements in your migrations, specify the database in your migration-table-name in the connections, i.e.

Property substitution

Migratus supports property substitution where migration files can contain placeholders with the format of

, these placeholders will be replaced with values found in the environment as a result of calling

Shell variables will be normalized into Java properties style by being lower cased and with

being transformed into
, e.g:

This feature is enabled when the

flag is set in the configuration.

Migratus will look for the following default properties:

  • migratus.schema
  • migratus.user
  • migratus.database
  • migratus.timestamp
    (defaults to the value of
    (.getTime (java.util.Date.))

Additional property can be specified using the

key or by providing a map of custom properties using the
{:store :database
 :properties {:env ["database.table"]
              :map {:database {:user "bob"}}}
 :db {:classname   "org.h2.Driver"
      :subprotocol "h2"
      :subname     "site.db"}}

For example, given the following template:

GRANT SELECT,INSERT ON ${database.table} TO ${database.user};

The environment variable associated with the

key will replace
tag in the template, while
{:database {:user "bob"}}
will replace


  • Add Migratus as a dependency to your
    :dependencies [[migratus ]]

There are hidden dependencies on slf4j inside migratus, so to avoid errors or silent failures you'll need to also add

[org.slf4j/slf4j-log4j12 ]

or if you're using Timbre

[com.fzakaria/slf4j-timbre ]

Next, create a namespace to manage the migrations:

(ns my-migrations
 (:require [migratus.core :as migratus]))

(def config {:store :database :migration-dir "migrations/" :init-script "init.sql" ;script should be located in the :migration-dir path ;defaults to true, some databases do not support ;schema initialization in a transaction :init-in-transaction? false :migration-table-name "foo_bar" :db {:classname "org.h2.Driver" :subprotocol "h2" :subname "site.db"}})

;initialize the database using the 'init.sql' script (migratus/init config)

;apply pending migrations (migratus/migrate config)

;rollback the migration with the latest timestamp (migratus/rollback config)

;bring up migrations matching the ids (migratus/up config 20111206154000)

;bring down migrations matching the ids (migratus/down config 20111206154000)

Alternative setup

It is possible to pass a

in place of a db spec map, e.g:
(ns my-migrations
  (:require [ :as jdbc]))

(def connection (jdbc/get-connection {:classname "org.h2.Driver" :subprotocol "h2" :subname "site.db"}))

(def config {:db {:connection connection}})

(ns my-migrations
  (:require [hikari-cp.core :as hk]))
;; Hikari:

(def datasource-options {:adapter "h2" :url "jdbc:h2:./site.db"})

(def config {:db {:datasource (hk/make-datasource datasource-options)}})

Running as native image (Postgres only)

PGMig is a standalone tool built with migratus that's compiled as a standalone GraalVM native image executable.

Generate migration files

Migratus also provides a convenience function for creating migration files:

(migratus/create config "create-user")
;; minimal config needed to call create while specifying the destination path
(migratus/create {:migration-dir "migrations"} "create-user")

This will result with up/down migration files being created prefixed with the current timestamp, e.g:


Code-based Migrations

Application developers often encounter situations where migrations cannot be easily expressed as a SQL script. For instance:

  • Executing programmatically-generated DDL statements (e.g. updating the schema of a dynamically-sharded table).
  • Transferring data between database servers.
  • Backfilling existing records with information that must be retrieved from an external system.

A common approach in these scenarios is to write one-off scripts which an admin must manually apply for each instance of the application, but issues arise if a script is not run or run multiple times.

Migratus addresses this problem by providing support for code-based migrations. You can write a migration as a Clojure function, and Migratus will ensure that it's run exactly once for each instance of the application.

Defining a code-based migration

Create a code-based migration by adding a

file to your migrations directory that contains the namespace and up/down functions to run, e.g.
{:ns app.migrations.import-users
 :up-fn migrate-up
 :down-fn migrate-down}

Then, in

(ns app.migrations.import-users)

(defn migrate-up [config] ;; do stuff here )

(defn migrate-down [config] ;; maybe undo stuff here )

  • The up and down migration functions should both accept a single parameter, which is the config map passed to Migratus (so your migrations can be configurable).
  • You can omit the up or down migration by setting
    in the EDN file.

Generate code-based migration files


function accepts an optional type parameter, which you can pass as
to create a new migration file.
(migratus/create config "import-users" :edn)

Mixing SQL and code-based migrations

You can include both SQL and code-based migrations in the same migrations directory, in which case they will be run intermixed in the order defined by their timestamps and their status stored in the same table in the migrations database. This way if there are dependencies between your SQL and code-based migrations, you can be assured that they'll run in the correct order.

Quick Start with Leiningen

Migratus provides a Leiningen plugin:

  • Add migratus-lein as a plugin in addition to the Migratus dependency:

Clojars Project

  • Add the following key and value to your project.clj:
:migratus {:store :database
           :migration-dir "migrations"
           :db {:classname "com.mysql.jdbc.Driver"
                :subprotocol "mysql"
                :subname "//localhost/migratus"
                :user "root"
                :password ""}}

To apply pending migrations:

  • Run
    lein migratus migrate

To rollback the migration with the last creation timestamp:

  • Run
    lein migratus rollback

Then follow the rest of the above instructions.


Migratus is configured via a configuration map that you pass in as its first parameter. The

key describes the type of store against which migrations should be run. All other keys/values in the configuration map are store specific.


To run migrations against a database use a :store of :database, and specify the database connection configuration in the :db key of the configuration map.

  • :migration-dir
    - directory where migration files are found
  • :db
    - database connection descriptor
  • :command-separator
    - the separator will be used to split the commands within each transaction when specified
  • :expect-results?
    - allows comparing migration query results using the
    -- expect n
  • :tx-handles-ddl?
    - skips the automatic down that occurs on exception
  • :init-script
    - string pointing to a script that should be run when the database is initialized
  • :init-in-transaction?
    - defaults to true, but some databases do not support schema initialization in a transaction
  • :migration-table-name
    - string specifying a custom name for the migration table, defaults to

example configurations

{:store :database
 :migration-dir "migrations"
 :db {:classname "com.mysql.jdbc.Driver"
      :subprotocol "mysql"
      :subname "//localhost/migratus"
      :user "root"
      :password ""}}


{:store :database
 :db {:connection-uri "jdbc:sqlite:foo_dev.db"}}


{:store :database
 :migration-dir "migrations"
 :db ~(get (System/getenv) "DATABASE_URL")}


key specifies the directory on the classpath in which to find SQL migration files. Each file should be named with the following pattern
where id is a unique integer
(ideally it should be a timestamp) for the migration, name is some human readable description of the migration, and direction is either

When the

key is set in the config, an assertion can be added to the migrations to check that the expected number of rows was updated:
-- expect 17;;
update foobar set thing = 'c' where thing = 'a';


-- expect 1;; delete from foobar where thing = 'c';

If Migratus is trying to run either the up or down migration and it does not exist, then an Exception will be thrown.

See test/migrations in this repository for an example of how database migrations work.

Modify sql fn

If you want to do some processing of the sql before it gets executed, you can provide a

in the config data structure to do so. It expects a sql-string and can return either a modified sql-string or a sequence of sql-strings. This is intended for use with and similar systems, where DDL statements need to be executed via an extension-provided function.


Migratus can be used programmatically by calling one of the following functions:

| Function | Description | |-----------------------------------------|--------------------------| |

| Runs a script to initialize the database, e.g: create a new schema. | |
| Create a new migration with the current date. | |
| Run
for any migrations that have not been run. Returns
if successful,
if the table is reserved. Supports thread cancellation. | |
| Run
for the last migration that was run. | |
| Run
all migrations after
. This only considers completed migrations, and will not migrate up. | |
| Run
for the specified migration ids. Will skip any migration that is already up. | |
| Run
for the specified migration ids. Will skip any migration that is already down. | |
| Returns a list of pending migrations. | |
| Run
for for any pending migrations which precede the given migration id (good for testing migrations). |

See the docstrings of each function for more details.

Migratus can also be used from leiningen if you add it as a plugin dependency.

:plugins [[migratus-lein ]]

And add a configuration :migratus key to your

:migratus {:store :database
           :migration-dir "migrations"
           :db {:classname "com.mysql.jdbc.Driver"
                :subprotocol "mysql"
                :subname "//localhost/migratus"
                :user "root"
                :password ""}}

You can then run the following tasks:

| Task | Description | |-----------------------------|--------------------------------------------------------------------------------------------| | lein migratus create | Create a new migration with the current date. | | lein migratus migrate | Run 'up' for any migrations that have not been run. | | lein migratus rollback | Run 'down' for the last migration that was run. | | lein migratus up & ids | Run 'up' for the specified migration ids. Will skip any migration that is already up. | | lein migratus down & ids | Run 'down' for the specified migration ids. Will skip any migration that is already down. | | lein migratus reset | Run 'down' for all migrations that have been run, and 'up' for all migrations. | | lein migratus pending | Run 'pending-list' to get all pending migrations. |

Quickstart with native Clojure projects

Clojars Project

See clj-migratus for more information.


Add the following to your

{:migratus {:extra-deps
            {orangefoxcollective/clj-migratus {:mvn/version "0.1.0"}}
            :main-opts ["-m" "clj-migratus.core"]}}

Create a Migratus configuration file

{:store :database
 :migration-dir "migrations"
 :db {:classname "com.mysql.jdbc.Driver"
      :subprotocol "mysql"
      :subname "//localhost/migratus"
      :user "root"
      :password ""}}

Then run

via the command line. For example:
$ clj -Amigratus init

$ clj -Amigratus migrate

$ clj -Amigratus create create-user-table

See Migratus Usage for documentation on each command.


Copyright © 2016 Paul Stadig, Dmitri Sotnikov

Licensed under the Apache License, Version 2.0.

We use cookies. If you continue to browse the site, you agree to the use of cookies. For more information on our use of cookies please see our Privacy Policy.