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sqitch(3pm) User Contributed Perl Documentation sqitch(3pm)

sqitch - Sensible database change management

  sqitch <command> [options] [command-options] [args]

Sqitch is a database change management application. What makes it different from your typical migration-style approaches? A few things:

Sqitch is not tied to any framework, ORM, or platform. Rather, it is a standalone change management system with no opinions about your database engine, application framework, or development environment.
Changes are implemented as scripts native to your selected database engine. Writing a PostgreSQL <https://postgresql.org/> application? Write SQL scripts for "psql" <https://www.postgresql.org/docs/current/static/app-psql.html>. Writing an Oracle <https://www.oracle.com/us/products/database/>-backed app? Write SQL scripts for SQL*Plus <https://www.orafaq.com/wiki/SQL*Plus>.
Database changes may declare dependencies on other changes -- even on changes from other Sqitch projects. This ensures proper order of execution, even when you've committed changes to your VCS out-of-order.
Sqitch manages changes and dependencies via a plan file, and employs a Merkle tree <https://en.wikipedia.org/wiki/Merkle_tree> pattern similar to Git <https://stackoverflow.com/a/18589734/> and Blockchain <https://medium.com/byzantine-studio/blockchain-fundamentals-what-is-a-merkle-tree-d44c529391d7> to ensure deployment integrity. As such, there is no need to number your changes, although you can if you want. Sqitch doesn't much care how you name your changes.
Up until you tag and release your project, you can modify your change deployment scripts as often as you like. They're not locked in just because they've been committed to your VCS. This allows you to take an iterative approach to developing your database schema. Or, better, you can do test-driven database development.

Ready to get started? Here's where:

Detailed tutorials demonstrating the creation, development, and maintenance of a database with Sqitch.
  • PostgreSQL Tutorial
  • SQLite Tutorial
  • MySQL Tutorial
  • Oracle Tutorial
  • Firebird Tutorial
  • Vertica Tutorial
  • Exasol Tutorial
  • Snowflake Tutorial
Slides from "Sane Database Management with Sqitch", presented to the Portland Perl Mongers in January, 2013.
Movie of "Sane Database Management with Sqitch", presented to the Portland PostgreSQL Users Group in September, 2012.
Three-hour tutorial session on using Git <https://git-scm.org/>, test-driven development with pgTAP <https://pgtap.org>, and change management with Sqitch.

"change"
A named unit of change. A change name must be used in the file names of its deploy and a revert scripts. It may also be used in a verify script file name.
"tag"
A known deployment state, pointing to a single change, typically corresponding to a release. Think of it is a version number or VCS revision. A given point in the plan may have any number of tags.
"state"
The current state of the database. This is represented by the most recently-deployed change. If the state of the database is the same as the most recent change, then it is considered "up-to-date".
"plan"
A list of one or more changes and their dependencies that define the order of deployment execution. The plan is stored in a "plan file," usually named sqitch.plan. Sqitch reads the plan file to determine what changes to execute to change the database from one state to another.
"target"
A named database to which to deploy changes. Always has an associated connection URI, and may also have an associated command-line client and registry name.
"registry"
The name of the database object where Sqitch's state and history data is stored. Typically a schema name (as in PostgreSQL and Oracle) or a database name (as in SQLite and MySQL).
"add"
The act of adding a change to the plan. Sqitch will generate scripts for the change, which you then may modify with the necessary code (typically DDLs) to actually deploy, revert, and verify the change.
"deploy"
The act of deploying changes to a database. Sqitch reads the plan, checks the current state of the database, and applies all the changes necessary to either bring the database up-to-date or to a requested state (a change name or tag).
"revert"
The act of reverting database changes to reach an earlier deployment state. Sqitch reads the list of deployed changes from the database and reverts them in the reverse of the order in which they were applied. All changes may be reverted, or changes may be reverted to a requested state (a change name or tag).
"committer"
User who commits or reverts changes to a database.
"planner"
User who adds a change to the plan.

  -C --chdir --cd DIR       Change to directory before performing any actions.
     --etc-path             Print path to etc directory and exit.
     --no-pager             Do not pipe output into a pager.
     --quiet                Quiet mode with non-error output suppressed.
  -V --verbose              Increment verbosity.
     --version              Print version number and exit.
     --help                 Show a list of commands and exit.
     --man                  Print introductory documentation and exit.

"--chdir"
"--cd"
"-C"
  sqitch --chdir dbproject
  sqitch --cd /usr/local/somedb
  sqitch -C dbcheckout

Change to the specified directory before performing any actions. Effectively the same as:

  (cd somedir && sqitch ...)

But a bit friendlier when managing multiple projects.

"--etc-path"
  sqitch --etc-path

Print out the path to the Sqitch etc directory and exit. This is the directory where the system-wide configuration file lives, as well as change script templates.

"--no-pager"
  sqitch --no-pager

Do not pipe Sqitch output into a pager. Currently limited to the "log" and "plan" commands.

"--quiet"
  sqitch --quiet

Suppress normal output messages. Error messages will still be emitted to "STDERR". Overrides any value specified by "--verbose".

"-V"
"--verbose"
  sqitch --verbose
  sqitch -VVV

Pass multiple times to specify a value between 0 and 3 to determine how verbose Sqitch should be. Unless "--quiet" is specified, the default is 1, meaning that Sqitch will output basic status messages as it does its thing. Values of 2 and 3 each cause greater verbosity. Ignored if "--quiet" is specified.

"--help"
  sqitch --help

Outputs a brief description all known Sqitch commands and exits.

"--man"
  sqitch --man

Outputs this documentation and exits.

"--version"
  sqitch --version

Outputs the program name and version and exits.

"init"
Create the plan file and directories for deploy, revert, and verify scripts if they do not already exist. This command is useful for starting a new Sqitch project.
"status"
Output information about the current deployment state of a database, including the name of the last deployed change, as well as any tags applied to it. If any changes in the plan have not been deployed, they will be listed separately.
"log"
Search and Output the complete change history of a database. Provides information about when changes were deployed, reverted, or failed, as well as who planned and committed the changes, and when.
"add"
Add a new change.
"tag"
List tags or tag the latest change.
"rework"
Rework an existing change.
"target"
Manage target databases.
"deploy"
Deploy changes to a database
"revert"
Revert changes from a database.
"verify"
Verify changes deployed to a database.
"config"
Get and set project, user, or system Sqitch options.
"bundle"
Bundle a Sqitch project for distribution. This command copies the Sqitch configuration, plan, and deploy, revert, and verify scripts to a directory, so that it can be packaged up for distribution, such as in an RPM or tarball.
"help"
Show help for a specific command or, if no command is specified, show the same documentation as "--help".

Sqitch configuration can be set up on a project, user, or system-wide basis. The format of the configuration file, named sqitch.conf, is the same as for git.

Here's an example of a configuration file that might be useful checked into a VCS for a project that deploys to PostgreSQL and stores its deployment scripts with the extension ddl under the "migrations" directory. It also wants bundle to be created in the _build/sql directory, and to deploy starting with the "gamma" tag:

  [core]
      engine    = pg
      top_dir   = migrations
      extension = ddl
  [engine "pg"]
      target    = widgetopolis
  [revert]
      to        = gamma
  [bundle]
      from      = gamma
      tags_only = yes
      dest_dir  = _build/sql
  [target "widgetopolis"]
      uri       = db:pg:widgetopolis

And here's an example of useful configuration in ~/.sqitch/sqitch.conf, to point to system-specific engine information:

  [user]
      name      = Marge N. OXVera
      email     = marge@example.com
  [engine "pg"]
      client    = /usr/local/pgsql/bin/psql
  [engine "mysql"]
      client    = /usr/local/mysql/bin/mysql
  [engine "oracle"]
      client    = /usr/local/instantclient_11_2/sqlplus
  [engine "sqlite"]
      client    = /usr/local/bin/sqlite3

Various commands read from the configuration file and adjust their operation accordingly. See sqitch-config for a list.

The original design for Sqitch was sketched out in a number of blog posts:

  • Simple SQL Change Management <https://justatheory.com/computers/databases/simple-sql-change-management.html>
  • VCS-Enabled SQL Change Management <https://justatheory.com/computers/databases/vcs-sql-change-management.html>
  • SQL Change Management Sans Duplication <https://justatheory.com/computers/databases/sql-change-management-sans-redundancy.html>

Other tools that do database change management include:

Numbered migrations for Ruby on Rails <https://rubyonrails.org/>.
Numbered changes in pure SQL, integrated with Perl's Module::Build build system. Does not support reversion.
Numbered migrations in pure SQL.
PostgreSQL-specific dependency-tracking solution by depesz <https://www.depesz.com/>.

David E. Wheeler <david@justatheory.com>

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2020-07-19 perl v5.30.3