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Name

sqitchtutorial-mssql - A tutorial introduction to Sqitch change management on MS SQL Server

Synopsis

sqitch *

Description

This tutorial explains how to create a sqitch-enabled MS SQL Server project, use a VCS for deployment planning, and work with other developers to make sure changes remain in sync and in the proper order.

We'll start by creating new project from scratch, a fictional antisocial networking site called Flipr. All examples use Git as the VCS and "MS SQL Server" as the storage engine.

If you'd like to manage an PostgreSQL database, see sqitchtutorial.

If you'd like to manage an SQLite database, see sqitchtutorial-sqlite.

If you'd like to manage an Oracle database, see sqitchtutorial-oracle.

If you'd like to manage an MySQL database, see sqitchtutorial-mysql.

If you'd like to manage an Firebird database, see sqitchtutorial-firebird.

If you'd like to manage an Vertica database, see sqitchtutorial-vertica.

Starting a New Project

Usually the first thing to do when starting a new project is to create a source code repository. So let's do that with Git:

> mkdir flipr
> cd flipr 
> git init .
Initialized empty Git repository in /flipr/.git/
> textpad README.md
> git add .
> git commit -am 'Initialize project, add README.'
[master (root-commit) fdf2a40] Initialize project, add README.
 1 file changed, 38 insertions(+)
 create mode 100644 README.md

If you're a Git user and want to follow along the history, the repository used in these examples is on GitHub.

Now that we have a repository, let's get started with Sqitch. Every Sqitch project must have a name associated with it, and, optionally, a unique URI. We recommend including the URI, as it increases the uniqueness of object identifiers internally, so let's specify one when we initialize Sqitch:

> sqitch --engine mssql init flipr --uri flipr
Created sqitch.conf
Created sqitch.plan
Created deploy/
Created revert/
Created verify/

Let's have a look at sqitch.conf:

> textpad sqitch.conf
[core]
        engine = mssql
        # plan_file = sqitch.plan
        # top_dir = .
        # deploy_dir = deploy
        # revert_dir = revert
        # verify_dir = verify
        # extension = sql
# [engine "mssql"]
        # target = db:mssql:
        # registry = sqitch
        # client = sqlcmd.exe

Good, it picked up on the fact that we're creating changes for the MSSQL engine, thanks to the --engine mssql option, and saved it to the file. Furthermore, it wrote a commented-out [engine "mssql"] section with all the available MSSQL engine-specific settings commented out and ready to be edited as appropriate.

So, edit the comments out to get Sqitch to use the settings. Then type the following to add new settings.

> sqitch config engine.mssql.target flipr_test
> sqitch config engine.mssql.integrated_security SSPI
> sqitch config engine.mssql.provider SQLNCLI10.1
> sqitch config engine.mssql.uri DBI:ADO
> sqitch config target.flipr_test.uri db:mssql://@localhost/flipr_test

Let's have a look at sqitch.conf now:

> cat sqitch.conf
[core]
        engine = mssql
        plan_file = sqitch.plan
        top_dir = .
        deploy_dir = deploy
        revert_dir = revert
        verify_dir = verify
        extension = sql
[engine "mssql"]
        target = flipr_test
        registry = sqitch
        client = sqlcmd.exe
        integrated_security = SSPI
        provider = SQLNCLI10.1
        uri = DBI:ADO
[target "flipr_test"]
        uri = db:mssql://@localhost/flipr_test

By default, Sqitch will read sqitch.conf in the current directory for settings. But it will also read ~/.sqitch/sqitch.conf for user-specific settings.

Let's tell it who we are, since this data will be used in all of our projects:

> sqitch config --user user.name 'Marge N. O’Vera'
> sqitch config --user user.email '[email protected]'

Have a look at ~/.sqitch/sqitch.conf and you'll see this:

> textpad ~/.sqitch/sqitch.conf
[user]
        name = Marge N. O’Vera
        email = [email protected]

Which means that Sqitch should be able to find mysql for any project, and that it will always properly identify us when planning and committing changes.

Back to the repository. Have a look at the plan file, sqitch.plan:

> textpad sqitch.plan
%syntax-version=1.0.0-b2
%project=flipr
%uri=flipr

Note that it has picked up on the name and URI of the app we're building. Sqitch uses this data to manage cross-project dependencies. The %syntax-version pragma is always set by Sqitch, so that it always knows how to parse the plan, even if the format changes in the future.

Let's commit these changes and start creating the database changes.

> git add .
> git commit -am 'Initialize Sqitch configuration.'
[master 79fe2cc] Initialize Sqitch configuration.
 2 files changed, 19 insertions(+)
 create mode 100644 sqitch.conf
 create mode 100644 sqitch.plan

Our First Change

First, our app will need a database user, so let's create one. Run this command:

> sqitch add appuser -m 'Creates an application user.'
Created deploy/appuser.sql
Created revert/appuser.sql
Created verify/appuser.sql
Added "appuser" to sqitch.plan

The add command adds a database change to the plan and writes deploy, revert, and verify scripts that represent the change. Now we edit these files. The deploy script's job is to create the table. By default, the deploy/appuser.sql file looks like this:

-- Deploy appuser

BEGIN TRANSACTION Deploy;

-- XXX Add DDLs here.

COMMIT TRANSACTION Deploy;

What we want to do is to replace the XXX comment with the CREATE USER statement, like so:

-- Deploy users

BEGIN TRANSACTION Deploy;

CREATE USER flipr;

COMMIT TRANSACTION Deploy;

The revert script's job is to precisely revert the change to the deploy script, so we edit this to revert/appuser.sql to look like this:

-- Revert users

BEGIN TRANSACTION Revert;

DROP USER flipr;

COMMIT TRANSACTION Revert;

Now we can try deploying this change. First create the flipr_test database and then run this command:

> sqitch deploy
Deploying changes to flipr_test
  + appuser .. ok

First Sqitch created the registry schema and tables used to track database changes. The registry schema is created in the database to which the appuser change was deployed; by default, its name is sqitch, and will be used to manage all projects on the database. Ideally, only Sqitch data will be stored in this schema.

If you'd like it to use a different schema, use sqitch config engine.mssql.registry $name to configure it (or via the target command; more below).

Next, Sqitch deploys changes to the target database, which we specified on the command-line. We only have one change so far; the + reinforces the idea that the change is being added to the database.

With this change deployed, if you connect to the database, you'll be able to see the user.

Trust, But Verify

But that's too much work. do you really want to do something like that after every deploy?

Here's where the verify script comes in. Its job is to test that the deploy did was it was supposed to. It should do so without regard to any data that might be in the database, and should throw an error if the deploy was not successful. The simplest way to see if a user exists is to check the sys.sysusers table. However, throwing an error in the event that the user does not exist is tricky in SQL Server. To simplify things, Sqitch provides a custom function you can use in your tests, verify. You pass an expression which evaluates to 1. If the expression evaluates to 0 or NULL, an exception will be thrown.

Give it a try. Put this query into verify/appuser.sql:

sqitch.verify "SELECT COUNT(*) FROM sys.sysusers WHERE name = 'flipr'";

This will work well as long as we know that the registry schema is named sqitch. If you've set core.mssql.registry to a different value, you will need to make sure you specify the correct schema name in the script.

Now you can run the verify script with the verify command:

> sqitch verify
Verifying flipr_test
  * appuser .. ok
Verify successful

Looks good! If you want to make sure that the verify script correctly dies if the table doesn't exist, temporarily change the user name in the script to something that doesn't exist, something like:

sqitch.verify "SELECT COUNT(*) FROM sys.sysusers WHERE name = 'nonesuch'";

Then verify again:

> sqitch verify
Verifying flipr_test
  * appuser .. # Verify script "verify\appuser.sql" failed
not ok

Verify Summary Report
---------------------
Changes: 1
Errors:  1
Verify failed

Don't forget to change the table name back before continuing!

Status, Revert, Log, Repeat

For purely informational purposes, we can always see how a deployment was recorded via the status command, which reads the tables from the registry database:

> sqitch status
# On database flipr_test
# Project:  flipr
# Change:   f56dd1a1ab029f398cec2cebb2ecc527fa0332c2
# Name:     appuser
# Deployed: 2013-12-31 13:13:17 -0800
# By:       Marge N. O’Vera <[email protected]>
# 
Nothing to deploy (up-to-date)

Let's make sure that we can revert the change:

> sqitch revert
Revert all changes from flipr_test? [Yes] 
  - appuser .. ok

The revert command first prompts to make sure that we really do want to revert. This is to prevent unnecessary accidents. You can pass the -y option to disable the prompt. Also, notice the - before the change name in the output, which reinforces that the change is being removed from the database. And now the schema should be gone.

And the status message should reflect as much:

> sqitch status
# On database flipr_test
No changes deployed

Of course, since nothing is deployed, the verify command has nothing to verify:

> sqitch verify
Verifying flipr_test
No changes deployed

However, we still have a record that the change happened, visible via the log command:

> sqitch log
On database flipr_test
Revert f56dd1a1ab029f398cec2cebb2ecc527fa0332c2
Name:      appuser
Committer: Marge N. O’Vera <[email protected]>
Date:      2013-12-31 13:26:39 -0800

    Creates a an application user.

Deploy f56dd1a1ab029f398cec2cebb2ecc527fa0332c2
Name:      appuser
Committer: Marge N. O’Vera <[email protected]>
Date:      2013-12-31 13:13:17 -0800

    Creates an application user.

Note that the actions we took are shown in reverse chronological order, with the revert first and then the deploy.

Cool. Now let's commit it.

> git add .
> git commit -m 'Add the "flipr" user.'
[master c63acb9] Add the "flipr" user.
 4 files changed, 23 insertions(+)
 create mode 100644 deploy/appuser.sql
 create mode 100644 revert/appuser.sql
 create mode 100644 verify/appuser.sql

And then deploy again. This time, let's use the --verify option, so that the verify script is applied when the change is deployed:

> sqitch deploy --verify
Deploying changes to flipr_test
  + appuser .. ok

And now the flipr user should be back.

When we look at the status, the deployment will be there:

> sqitch status
# On database flipr_test
# Project:  flipr
# Change:   f56dd1a1ab029f398cec2cebb2ecc527fa0332c2
# Name:     appuser
# Deployed: 2013-12-31 13:28:23 -0800
# By:       Marge N. O’Vera <[email protected]>
# 
Nothing to deploy (up-to-date)

Deploy with Dependency

Let's add another change, this time to create a table. Our app will need users, of course, so we'll create a table for them. First, add the new change:

> sqitch add users --requires appuser -m 'Creates table to track our users.'
Created deploy/users.sql
Created revert/users.sql
Created verify/users.sql
Added "users [appuser]" to sqitch.plan

Note that we're requiring the appuser change as a dependency of the new users change. Although that change has already been added to the plan and therefore should always be applied before the users change, it's a good idea to be explicit about dependencies.

Now edit the scripts. When you're done, deploy/users.sql should look like this:

-- Deploy users
-- requires: appuser

CREATE TABLE dbo.users (
    nickname  VARCHAR(512) NOT NULL,
    password  VARCHAR(512) NOT NULL,
    timestamp DATETIME  NOT NULL,
PRIMARY KEY CLUSTERED
(
        nickname ASC
        )
);

GRANT SELECT ON dbo.users TO flipr;

IF EXISTS (SELECT * FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA
= 'sqitch' AND TABLE_NAME = 'users')

INSERT INTO dbo.users SELECT * FROM sqitch.users;

A few things to notice here. On the second line, the dependence on the appuser change has been listed. This doesn't do anything, but the default SQL Server deploy template lists it here for your reference while editing the file. Useful, right?

The flipr user has been granted SELECT access to the table. The app needs to read the data, right? This is why we need to require the appuser change.

Because this is a table, we also check if there was a backup of the data on the sqitch schema, so that any data is not lost.

Now for the verify script. Add this to verify/users.sql;

sqitch.verify "SELECT COUNT(*) FROM INFORMATION_SCHEMA.TABLES WHERE
TABLE_SCHEMA = 'dbo' AND TABLE_NAME = 'users'"

Now for the revert script. Add this to revert/users.sql:

IF EXISTS (SELECT * FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA
= 'sqitch' AND TABLE_NAME = 'users')

DROP TABLE sqitch.users;

SELECT * INTO sqitch.users FROM dbo.users;

DROP TABLE dbo.users;

We first drop the backup table on sqitch and then take a backup of the users table before dropping it. Let's deploy this bad boy:

> sqitch deploy
Deploying changes to flipr_test
  + users .. ok

We know, since verification is enabled, that the table must have been created. But for the purposes of visibility, have a quick look to see if that is so.

We can also verify all currently deployed changes with the verify command:

> sqitch verify
Verifying flipr_test
  * appuser .. ok
  * users .... ok
Verify successful

Now have a look at the status:

> sqitch status
# On database flipr_test
# Project:  flipr
# Change:   2bd1190fdb324c2609f0c7f0cef73d8cb434ba0e
# Name:     users
# Deployed: 2013-12-31 13:34:25 -0800
# By:       Marge N. O’Vera <[email protected]>
# 
Nothing to deploy (up-to-date)

Success! Let's make sure we can revert the change, as well:

> sqitch revert --to @HEAD^^ -y
Reverting changes to appuser from flipr_test
  - users .. ok

Note that we've used the --to option to specify the change to revert to. And what do we revert to? The symbolic tag @HEAD, when passed to revert, always refers to the last change deployed to the database. (For other commands, it refers to the last change in the plan.) Appending the carets (^^) tells Sqitch to select the change prior to the last deployed change. So we revert to appuser, the penultimate change. The other potentially useful symbolic tag is @ROOT, which refers to the first change deployed to the database (or in the plan, depending on the command).

Back to the database. The users table should be gone but the flipr user should still be around.

The status command politely informs us that we have undeployed changes:

> sqitch status
# On database flipr_test
# Project:  flipr
# Change:   f56dd1a1ab029f398cec2cebb2ecc527fa0332c2
# Name:     appuser
# Deployed: 2013-12-31 13:28:23 -0800
# By:       Marge N. O’Vera <[email protected]>
# 
Undeployed change:
  * users

As does the verify command:

> sqitch verify
Verifying flipr_test
  * appuser .. ok
Undeployed change:
  * users
Verify successful

Note that the verify is successful, because all currently-deployed changes are verified. The list of undeployed changes (just "users" here) reminds us about the current state.

Okay, let's commit and deploy again:

> git add .
> git commit -am 'Add users table.'
[master 7c99fb0] Add users table.
 4 files changed, 31 insertions(+)
 create mode 100644 deploy/users.sql
 create mode 100644 revert/users.sql
 create mode 100644 verify/users.sql
> sqitch deploy
Deploying changes to flipr_test
  + users .. ok

Looks good. Check the status:

> sqitch status
# On database flipr_test
# Project:  flipr
# Change:   2bd1190fdb324c2609f0c7f0cef73d8cb434ba0e
# Name:     users
# Deployed: 2013-12-31 13:37:02 -0800
# By:       Marge N. O’Vera <[email protected]>
# 
Nothing to deploy (up-to-date)

Excellent. Let's do some more!

Add Two at Once

Let's add a couple more changes to add functions for managing users.

> sqitch add insert_user --requires users --requires appuser \
  -m 'Creates a function to insert a user.'
Created deploy/insert_user.sql
Created revert/insert_user.sql
Created verify/insert_user.sql
Added "insert_user [users appuser]" to sqitch.plan

> sqitch add change_pass --requires users --requires appuser \
  -m 'Creates a function to change a user password.'
Created deploy/change_pass.sql
Created revert/change_pass.sql
Created verify/change_pass.sql
Added "change_pass [users appuser]" to sqitch.plan

Now might be a good time to have a look at the deployment plan:

> textpad sqitch.plan
%syntax-version=1.0.0-b2
%project=flipr
%uri=flipr

appuser 2013-12-31T21:04:04Z Marge N. O’Vera <[email protected]> # Creates a an application user.
users [appuser] 2013-12-31T21:32:48Z Marge N. O’Vera <[email protected]> # Creates table to track our users.
insert_user [users appuser] 2013-12-31T21:37:29Z Marge N. O’Vera <[email protected]> # Creates a function to insert a user.
change_pass [users appuser] 2013-12-31T21:37:36Z Marge N. O’Vera <[email protected]> # Creates a function to change a user password.

Each change appears on a single line with the name of the change, a bracketed list of dependencies, a timestamp, the name and email address of the user who planned the change, and a note.

Let's write the code for the new changes. Here's what deploy/insert_user.sql should look like:

-- Deploy insert_user
-- requires: users
-- requires: appuser


CREATE PROCEDURE insert_user
    @nickname VARCHAR(512),
    @password VARCHAR(512)
AS
    INSERT INTO users (nickname, password, timestamp)
    VALUES (@nickname, HashBytes('sha1',@password),GETDATE());

GRANT EXECUTE ON insert_user to flipr;

Here's what verify/insert_user.sql might look like, using the Sqitch verify function again:

-- Verify insert_user

sqitch.verify "SELECT COUNT(*) FROM INFORMATION_SCHEMA.ROUTINES WHERE
ROUTINE_SCHEMA = 'dbo' AND ROUTINE_NAME = 'insert_user';

We simply take advantage of the fact that the new procedure should be listed in the INFORMATION_SCHEMA.ROUTINES table and throw an exception if it does not exist.

And revert/insert_user.sql should look something like this:

-- Revert insert_user

DROP PROCEDURE insert_user;

Now for change_pass; deploy/change_pass.sql might look like this:

-- Deploy change_pass
-- requires: users
-- requires: appuser

CREATE PROCEDURE change_pass
    @nickname VARCHAR(512),
    @oldpass  VARCHAR(512),
    @newpass  VARCHAR(512)
AS
    UPDATE users
       SET password = HashBytes('sha1',@newpass)
     WHERE nickname = @nickname
       AND password = HashBytes('sha1',@oldpass);
    
GRANT EXECUTE ON change_pass to flipr;

Use verify in verify/change_pass.sql again:

sqitch.verify "SELECT COUNT(*) FROM INFORMATION_SCHEMA.ROUTINES WHERE
ROUTINE_SCHEMA = 'dbo' AND ROUTINE_NAME = 'change_pass';

And of course, its revert script, revert/change_pass.sql, should look something like:

-- Revert change_pass
 
DROP PROCEDURE change_pass;

Try em out!

> sqitch deploy
Deploying changes to flipr_test
  + insert_user .. ok
  + change_pass .. ok

Do we have the procedures? Of course we do, they were verified. Still, do have a look.

And what's the status?

> sqitch status
# On database flipr_test
# Project:  flipr
# Change:   b0a598b91ce97cf1b95ded97a6452bf03231a2cd
# Name:     change_pass
# Deployed: 2013-12-31 13:39:49 -0800
# By:       Marge N. O’Vera <[email protected]>
# 
Nothing to deploy (up-to-date)

Looks good. Let's make sure revert works:

> sqitch revert -y --to @HEAD^^
Reverting changes to users from flipr_test
  - change_pass .. ok
  
> sqitch revert -y --to @HEAD^^  
Reverting changes to users from flipr_test
  - insert_user .. ok

Note the use of @HEAD^^ to specify that the revert be to one change prior the last deployed change. Looks good. Let's do the commit and re-deploy dance:

> git add .
> git commit -m 'Add `insert_user()` and `change_pass()`.'
[master 0f95e13] Add `insert_user()` and `change_pass()`.
 7 files changed, 86 insertions(+)
 create mode 100644 deploy/change_pass.sql
 create mode 100644 deploy/insert_user.sql
 create mode 100644 revert/change_pass.sql
 create mode 100644 revert/insert_user.sql
 create mode 100644 verify/change_pass.sql
 create mode 100644 verify/insert_user.sql

> sqitch deploy
Deploying changes to flipr_test
  + insert_user .. ok
  + change_pass .. ok

> sqitch status
# On database flipr_test
# Project:  flipr
# Change:   b0a598b91ce97cf1b95ded97a6452bf03231a2cd
# Name:     change_pass
# Deployed: 2013-12-31 13:40:40 -0800
# By:       Marge N. O’Vera <[email protected]>
# 
Nothing to deploy (up-to-date)

> sqitch verify
Verifying flipr_test
  * appuser ...... ok
  * users ........ ok
  * insert_user .. ok
  * change_pass .. ok
Verify successful

Great, we're fully up-to-date!

Ship It!

Let's do a first release of our app. Let's call it 1.0.0-dev1 Since we want to have it go out with deployments tied to the release, let's tag it:

> sqitch tag v1.0.0-dev1 -m "Tag v1.0.0-dev1."
Tagged "change_pass" with @v1.0.0-dev1
> git commit -am "Tag the database with v1.0.0-dev1."
[master 0595297] Tag the database with v1.0.0-dev1.
 1 file changed, 1 insertion(+)
> git tag v1.0.0-dev1 -am "Tag v1.0.0-dev1"

Now let's bundle everything up for release:

> sqitch bundle
Bundling into bundle/
Writing config
Writing plan
Writing scripts
  + appuser
  + users
  + insert_user
  + change_pass @v1.0.0-dev1

Now we can package the bundle directory and distribute it. When it gets installed somewhere, users can use Sqitch to deploy to the database.

Let's try deploying the bundle:

First, create a new database on a server, say the flipr database on the sdhis4 server . Then go to the bundle directory:

> cd bundle

Now enter the following to repoint the deployment:

> sqitch config engine.mssql.target flipr_live
> sqitch config target.flipr_live.uri db:mssql://@sdhis4/flipr

Let's have a look at sqitch.conf now:

> textpad sqitch.conf
[core]
        engine = mssql
        plan_file = sqitch.plan
        top_dir = .
        deploy_dir = deploy
        revert_dir = revert
        verify_dir = verify
        extension = sql
[engine "mssql"]
        target = flipr_live
        registry = sqitch
        client = sqlcmd.exe
        integrated_security = SSPI
        provider = SQLNCLI10.1
        uri = DBI:ADO
[target "flipr_test"]
        uri = db:mssql://@localhost/flipr_test
[target "flipr_live"]
        uri = db:mssql://@sdhis4/flipr


Now deploy it:

> sqitch deploy
Deploying changes to flipr_live
  + appuser ................... ok
  + users ..................... ok
  + insert_user ............... ok
  + change_pass @v1.0.0-dev1 .. ok

Great, all four changes were deployed and change_pass was tagged with @v1.0.0-dev1. Let's have a look at the status:

> sqitch status
# On database flipr_live
# Project:  flipr
# Change:   b0a598b91ce97cf1b95ded97a6452bf03231a2cd
# Name:     change_pass
# Tag:      @v1.0.0-dev1
# Deployed: 2013-12-31 13:44:04 -0800
# By:       Marge N. O’Vera <[email protected]>
# 
Nothing to deploy (up-to-date)

Looks good, eh? Go ahead and revert it:

> sqitch revert -y
Reverting all changes from flipr_live
  - change_pass @v1.0.0-dev1 .. ok
  - insert_user ............... ok
  - users ..................... ok
  - appuser ................... ok

Now package it up and ship it!

Flip Out

Now that we've got the basics of user management done, let's get to work on the core of our product, the "flip." Since other folks are working on other tasks in the repository, we'll work on a branch, so we can all stay out of each other's way. So let's branch:

> git checkout -b flips
Switched to a new branch 'flips'

Now we can add a new change to create a table for our flips.

> sqitch add flips -r appuser -r users -m "Adds table for storing flips."
Created deploy/flips.sql
Created revert/flips.sql
Created verify/flips.sql
Added "flips [appuser users]" to sqitch.plan

You know the drill by now. Edit deploy/flips.sql:

-- Deploy flips
-- requires: appuser
-- requires: users

CREATE TABLE dbo.flips (
    id        INT   PRIMARY KEY,
    nickname  VARCHAR(512) NOT NULL REFERENCES dbo.users(nickname),
    body      VARCHAR(512) NOT NULL,
    timestamp DATETIME NOT NULL DEFAULT GETDATE()
);

And edit revert/flips.sql:

-- Revert flips

DROP TABLE dbo.flips;

And give it a whirl:

> sqitch deploy
Deploying changes to flipr_test
  + flips .. ok

Look good?

> sqitch status --show-tags
# On database flipr_test
# Project:  flipr
# Change:   b3ccd37da58ac232c23edfa0adaf2d6f483842fd
# Name:     flips
# Deployed: 2013-12-31 13:55:04 -0800
# By:       Marge N. O’Vera <[email protected]>
# 
# Tag:
#   @v1.0.0-dev1 - 2013-12-31 13:55:04 -0800 - Marge N. O’Vera <[email protected]>
# 
Nothing to deploy (up-to-date)

Note the use of --show tags to show all the deployed tags. Now make it so:

> git add .
> git commit -am "Add flips table."
[flips ce1b53d] Add flips table.
 4 files changed, 37 insertions(+)
 create mode 100644 deploy/flips.sql
 create mode 100644 revert/flips.sql
 create mode 100644 verify/flips.sql

Wash, Rinse, Repeat

Now comes the time to add functions to manage flips. I'm sure you have things nailed down now. Go ahead and add insert_flip and delete_flip changes and commit them. The insert_flip deploy script might look something like:

-- Deploy insert_flip
-- requires: flips
-- requires: appuser

CREATE PROCEDURE insert_flip
    @nickname VARCHAR(512),
    @body     VARCHAR(180)
AS
    INSERT INTO flips (nickname, body)
    VALUES (@nickname, @body);

GRANT EXECUTE ON insert_flip to flipr;

And the delete_flip deploy script might look something like:

-- Deploy delete_flip
-- requires: flips
-- requires: appuser

CREATE PROCEDURE delete_flip
    @flip_id INT
AS
    DELETE FROM flips WHERE id = @flip_id;

GRANT EXECUTE ON delete_flip to flipr;

The verify scripts are:

-- Verify insert_flip

sqitch.verify "SELECT COUNT(*) FROM INFORMATION_SCHEMA.ROUTINES WHERE
ROUTINE_SCHEMA = 'dbo' AND ROUTINE_NAME = 'insert_flip'"

And:

-- Verify delete_flip

sqitch.verify "SELECT COUNT(*) FROM INFORMATION_SCHEMA.ROUTINES WHERE
ROUTINE_SCHEMA = 'dbo' AND ROUTINE_NAME = 'delete_flip'"

The revert scripts are:

-- Revert insert_flip

DROP PROCEDURE insert_flip;

And:

-- Revert delete_flip

DROP PROCEDURE delete_flip;

Test deploy and revert, then commit it to the repository. The status should end up looking something like this:

> sqitch status --show-tags
# On database flipr_test
# Project:  flipr
# Change:   7bf30e6b7b0a4e61f30dd4148f5b837bdddae086
# Name:     delete_flip
# Deployed: 2013-12-31 13:58:54 -0800
# By:       Marge N. O’Vera <[email protected]>
# 
# Tag:
#   @v1.0.0-dev1 - 2013-12-31 13:55:04 -0800 - Marge N. O’Vera <[email protected]>
# 
Nothing to deploy (up-to-date)

Good, we've finished this feature. Now make it so:

> git add .
> git commit -am "Add manage flips procedures."
[flips a44c2d5] Add manage flips procedures.
7 files changed, 39 insertions(+)
create mode 100644 deploy/delete_flip.sql
create mode 100644 deploy/insert_flip.sql
create mode 100644 revert/delete_flip.sql
create mode 100644 revert/insert_flip.sql
create mode 100644 verify/delete_flip.sql
create mode 100644 verify/insert_flip.sql

Time to merge back into master.

[However in the meantime someone else has been working on the master branch.

> git checkout master
Switched to branch 'master'

> sqitch add flipr_schema -m "Add flipr schema."
Created deploy\flipr_schema.sql
Created revert\flipr_schema.sql
Created verify\flipr_schema.sql
Added "flipr_schema" to sqitch.plan

> git add .
> git commit -am "Add flipr schema."

]

Emergency

> git merge --no-ff flips
Auto-merging sqitch.plan
CONFLICT (content): Merge conflict in sqitch.plan
Automatic merge failed; fix conflicts and then commit the result.

Oh, a conflict in sqitch.plan. Not too surprising, since both the merged lists branch and our flips branch added changes to the plan. Let's try a different approach.

The truth is, we got lazy. Those changes when we pulled master from the origin should have raised a red flag. It's considered a bad practice not to look at what's changed in master before merging in a branch. What one should do is either:

  • Rebase the flips branch from master before merging. This "rewinds" the branch changes, pulls from master, and then replays the changes back on top of the pulled changes.

  • Create a patch and apply that to master. This is the sort of thing you might have to do if you're sending changes to another user, especially if the VCS is not Git.

So let's restore things to how they were at master:

> git reset --hard HEAD
HEAD is now at 5a58089 Add flipr schema.

That throws out our botched merge. Now let's go back to our branch and rebase it on master:

> git checkout flips
Switched to branch 'flips'
> git rebase master
First, rewinding head to replay your work on top of it...
Applying: Add flips table.
Using index info to reconstruct a base tree...
M       sqitch.plan
Falling back to patching base and 3-way merge...
Auto-merging sqitch.plan
CONFLICT (content): Merge conflict in sqitch.plan
Failed to merge in the changes.
Patch failed at 0001 Add flips table.
The copy of the patch that failed is found in:
   .git/rebase-apply/patch

When you have resolved this problem, run "git rebase --continue".
If you prefer to skip this patch, run "git rebase --skip" instead.
To check out the original branch and stop rebasing, run "git rebase --abort".

Oy, that's kind of a pain. It seems like no matter what we do, we'll need to resolve conflicts in that file. Except in Git. Fortunately for us, we can tell Git to resolve conflicts in sqitch.plan differently. Because we only ever append lines to the file, we can have it use the "union" merge driver, which, according to its docs:

    Run 3-way file level merge for text files, but take lines from both versions, instead of leaving conflict markers. This tends to leave the added lines in the resulting file in random order and the user should verify the result. Do not use this if you do not understand the implications.

This has the effect of appending lines from all the merging files, which is exactly what we need. So let's give it a try. First, back out the botched rebase:

> git rebase --abort

Now add the union merge driver to .gitattributes for sqitch.plan and rebase again:

> echo sqitch.plan merge=union > .gitattributes
> git rebase master
First, rewinding head to replay your work on top of it...
Applying: Add flips table.
Using index info to reconstruct a base tree...
M       sqitch.plan
Falling back to patching base and 3-way merge...
Auto-merging sqitch.plan
Applying: Add functions to insert and delete flips.
Using index info to reconstruct a base tree...
M       sqitch.plan
Falling back to patching base and 3-way merge...
Auto-merging sqitch.plan

Ah, that looks a bit better. Let's have a look at the plan:

> textpad sqitch.plan
%syntax-version=1.0.0-b2
%project=flipr
%uri=https://github.com/theory/sqitch-mssql-intro/

appuser 2013-12-31T21:04:04Z Marge N. O’Vera <[email protected]> # Creates a an application user.
users [appuser] 2013-12-31T21:32:48Z Marge N. O’Vera <[email protected]> # Creates table to track our users.
insert_user [users appuser] 2013-12-31T21:37:29Z Marge N. O’Vera <[email protected]> # Creates a function to insert a user.
change_pass [users appuser] 2013-12-31T21:37:36Z Marge N. O’Vera <[email protected]> # Creates a function to change a user password.
@v1.0.0-dev1 2013-12-31T21:41:08Z Marge N. O’Vera <[email protected]> # Tag v1.0.0-dev1.

lists [appuser users] 2013-12-31T21:46:22Z Marge N. O’Vera <[email protected]> # Adds table for storing lists.
insert_list [lists appuser] 2013-12-31T21:48:14Z Marge N. O’Vera <[email protected]> # Creates a function to insert a list.
delete_list [lists appuser] 2013-12-31T21:49:41Z Marge N. O’Vera <[email protected]> # Creates a function to insert a list.
flips [appuser users] 2013-12-31T21:53:03Z Marge N. O’Vera <[email protected]> # Adds table for storing flips.
insert_flip [flips appuser] 2013-12-31T21:56:12Z Marge N. O’Vera <[email protected]> # Creates a function to insert a flip.
delete_flip [flips appuser] 2013-12-31T21:56:22Z Marge N. O’Vera <[email protected]> # Creates a function to delete a flip.

Note that it has appended the changes from the merged "lists" branch, and then merged the changes from our "flips" branch. Test it to make sure it works as expected:

> sqitch rebase -y
Reverting all changes from flipr_test
  - delete_flip ............... ok
  - insert_flip ............... ok
  - flips ..................... ok
  - change_pass @v1.0.0-dev1 .. ok
  - insert_user ............... ok
  - users ..................... ok
  - appuser ................... ok
Deploying changes to flipr_test
  + appuser ................... ok
  + users ..................... ok
  + insert_user ............... ok
  + change_pass @v1.0.0-dev1 .. ok
  + lists ..................... ok
  + insert_list ............... ok
  + delete_list ............... ok
  + flips ..................... ok
  + insert_flip ............... ok
  + delete_flip ............... ok

Note the use of rebase, which combines a revert and a deploy into a single command. Handy, right? It correctly reverted our changes, and then deployed them all again in the proper order. So let's commit .gitattributes; seems worthwhile to keep that change:

> git add .
> git commit -m "Add '.gitattributes' with union merge for 'sqitch.plan'."
[flips d813f7c] Add '.gitattributes' with union merge for 'sqitch.plan'.
 1 file changed, 1 insertion(+)
 create mode 100644 .gitattributes

Merges Mastered

And now, finally, we can merge into master:

> git checkout master
Switched to branch 'master'
> git merge --no-ff flips -m "Merge branch 'flips'"
Merge made by the 'recursive' strategy.
 .gitattributes         |  1 +
 deploy/delete_flip.sql | 22 ++++++++++++++++++++++
 deploy/flips.sql       | 16 ++++++++++++++++
 deploy/insert_flip.sql | 24 ++++++++++++++++++++++++
 revert/delete_flip.sql |  7 +++++++
 revert/flips.sql       |  7 +++++++
 revert/insert_flip.sql |  7 +++++++
 sqitch.plan            |  3 +++
 verify/delete_flip.sql | 10 ++++++++++
 verify/flips.sql       | 12 ++++++++++++
 verify/insert_flip.sql | 10 ++++++++++
 11 files changed, 119 insertions(+)
 create mode 100644 .gitattributes
 create mode 100644 deploy/delete_flip.sql
 create mode 100644 deploy/flips.sql
 create mode 100644 deploy/insert_flip.sql
 create mode 100644 revert/delete_flip.sql
 create mode 100644 revert/flips.sql
 create mode 100644 revert/insert_flip.sql
 create mode 100644 verify/delete_flip.sql
 create mode 100644 verify/flips.sql
 create mode 100644 verify/insert_flip.sql

And double-check our work:

> textpad sqitch.plan
%syntax-version=1.0.0-b2
%project=flipr
%uri=https://github.com/theory/sqitch-mysql-intro/

appuser 2013-12-31T21:04:04Z Marge N. O’Vera <[email protected]> # Creates a an application user.
users [appuser] 2013-12-31T21:32:48Z Marge N. O’Vera <[email protected]> # Creates table to track our users.
insert_user [users appuser] 2013-12-31T21:37:29Z Marge N. O’Vera <[email protected]> # Creates a function to insert a user.
change_pass [users appuser] 2013-12-31T21:37:36Z Marge N. O’Vera <[email protected]> # Creates a function to change a user password.
@v1.0.0-dev1 2013-12-31T21:41:08Z Marge N. O’Vera <[email protected]> # Tag v1.0.0-dev1.

lists [appuser users] 2013-12-31T21:46:22Z Marge N. O’Vera <[email protected]> # Adds table for storing lists.
insert_list [lists appuser] 2013-12-31T21:48:14Z Marge N. O’Vera <[email protected]> # Creates a function to insert a list.
delete_list [lists appuser] 2013-12-31T21:49:41Z Marge N. O’Vera <[email protected]> # Creates a function to insert a list.
flips [appuser users] 2013-12-31T21:53:03Z Marge N. O’Vera <[email protected]> # Adds table for storing flips.
insert_flip [flips appuser] 2013-12-31T21:56:12Z Marge N. O’Vera <[email protected]> # Creates a function to insert a flip.
delete_flip [flips appuser] 2013-12-31T21:56:22Z Marge N. O’Vera <[email protected]> # Creates a function to delete a flip.

Much much better, a nice clean master now. And because it is now identical to the "flips" branch, we can just carry on. Go ahead and tag it, bundle, and release:

> sqitch tag v1.0.0-dev2 -m "Tag v1.0.0-dev2."
Tagged "delete_flip" with @v1.0.0-dev2
> git commit -am "Tag the database with v1.0.0-dev2."
[master 76d6e15] Tag the database with v1.0.0-dev2.
 1 file changed, 1 insertion(+)
> git tag v1.0.0-dev2 -am "Tag v1.0.0-dev2"
> sqitch bundle --dest-dir flipr-1.0.0-dev2
Bundling into flipr-1.0.0-dev2
Writing config
Writing plan
Writing scripts
  + appuser
  + users
  + insert_user
  + change_pass @v1.0.0-dev1
  + lists
  + insert_list
  + delete_list
  + flips
  + insert_flip
  + delete_flip @v1.0.0-dev2

Note the use of the --dest-dir option to sqitch bundle. Just a nicer way to create the top-level directory name so we don't have to rename it from bundle.

In Place Changes

Someone wants to change insert_user to use CURRENT_TIMESTAMP instead of GETDATE().

Normally, modifying procedures in database changes is a PITA. You have to make changes like these:

  1. Copy deploy/insert_user.sql to deploy/insert_user_current_timestamp.sql.

  2. Edit deploy/insert_user_current_timestamp.sql to switch from GETDATE() to CURRENT_TIMESTAMP.

  3. Copy deploy/insert_user.sql to revert/insert_user_current_timestamp.sql. Yes, copy the original change script to the new revert change.

  4. Copy verify/insert_user.sql to verify/insert_user_current_timestamp.sql.

  5. Edit verify/insert_user_current_timestamp.sql to test that the procedure now properly uses CURRENT_TIMESTAMP.

  6. Test the changes to make sure you can deploy and revert the insert_user_current_timestamp change.

But you can have Sqitch do it for you. The only requirement is that a tag appear between the two instances of a change we want to modify. In general, you're going to make a change like this after a release, which you've tagged anyway, right? Well we have, with @v1.0.0-dev2 added in the previous section. With that, we can let Sqitch do most of the hard work for us, thanks to the rework command, which is similar to add:

> sqitch rework insert_user -m "Change insert_user to use current_timestamp."
Added "insert_user [[email protected]]" to sqitch.plan.
Modify these files as appropriate:
  * deploy/insert_user.sql
  * revert/insert_user.sql
  * verify/insert_user.sql

Oh, so we can edit those files in place. Nice! How does Sqitch do it? Well, in point of fact, it has copied the files to stand in for the previous instance of the insert_user change, which we can see via git status:

> git status
# On branch master
# Your branch is ahead of 'origin/master' by 5 commits.
#   (use "git push" to publish your local commits)
#
# Changes not staged for commit:
#   (use "git add <file>..." to update what will be committed)
#   (use "git checkout -- <file>..." to discard changes in working directory)
#
#       modified:   revert/insert_user.sql
#       modified:   sqitch.plan
#
# Untracked files:
#   (use "git add <file>..." to include in what will be committed)
#
#       deploy/[email protected]
#       revert/[email protected]
#       verify/[email protected]
no changes added to commit (use "git add" and/or "git commit -a")

The "untracked files" part of the output is the first thing to notice. They are all named [email protected]. What that means is: "the insert_user change as it was implemented as of the @v1.0.0-dev2 tag." These are copies of the original scripts, and thereafter Sqitch will find them when it needs to run scripts for the first instance of the insert_user change. As such, it's important not to change them again. But hey, if you're reworking the change, you shouldn't need to.

The other thing to notice is that revert/insert_user.sql has changed. Sqitch replaced it with the original deploy script. As of now, deploy/insert_user.sql and revert/insert_user.sql are identical. This is on the assumption that the deploy script will be changed (we're reworking it, remember?), and that the revert script should actually change things back to how they were before. Of course, the original deploy script may not be idempotent -- that is, able to be applied multiple times without changing the result beyond the initial application. If it's not, you will likely need to modify it so that it properly restores things to how they were after the original deploy script was deployed. Or, more simply, it should revert changes back to how they were as-of the deployment of deploy/[email protected].

For SQL Server we can achieve this by modifying the scripts to ALTER PROCEDURE. So let's do it. We'll modify the scripts to ALTER the PROCEDURES to use CURRENT_TIMESTAMP. Make this change to deploy/insert_user.sql:

-- Deploy insert_user
-- requires: users
-- requires: appuser


ALTER PROCEDURE insert_user
    @nickname VARCHAR(512),
    @password VARCHAR(512)
AS
    INSERT INTO users (nickname, password, timestamp)
    VALUES (@nickname, HashBytes('sha1',@password),CURRENT_TIMESTAMP);



GRANT EXECUTE ON insert_user to flipr;

We also need to change the revert script, revert/insert_user.sql to use ALTER:

-- Deploy insert_user
-- requires: users
-- requires: appuser


ALTER PROCEDURE insert_user
    @nickname VARCHAR(512),
    @password VARCHAR(512)
AS
    INSERT INTO users (nickname, password, timestamp)
    VALUES (@nickname, HashBytes('sha1',@password),GETDATE());



GRANT EXECUTE ON insert_user to flipr;

And now we're ready to try a deployment:

>     sqitch deploy
Deploying changes to flipr_test
  + insert_user .. ok

So, are the changes deployed?

CREATE PROCEDURE dbo.insert_user
     @nickname VARCHAR(512),
     @password VARCHAR(512)
 AS
     INSERT INTO users (nickname, password, timestamp)
     VALUES (@nickname, HashBytes('sha1',@password),CURRENT_TIMESTAMP);

Awesome, the stored passwords are different now. But can we revert, even though we haven't written any reversion scripts?

> sqitch revert --to @HEAD^^ -y
Reverting changes to delete_flip @v1.0.0-dev2 from flipr_test
  - insert_user .. ok

Did that work, is GETDATE() back?

CREATE PROCEDURE dbo.insert_user
      @nickname VARCHAR(512),
      @password VARCHAR(512)
  AS
      INSERT INTO users (nickname, password, timestamp)
    VALUES (@nickname, HashBytes('sha1',@password),GETDATE());

Yes, it works! Sqitch properly finds the original instances of these changes in the new script files that include tags.

But what about the verify script? How can we verify that the functions have been modified to use CURRENT_TIMESTAMP? I think the simplest thing to do is to examine the body of the function as returned by INFORMATION_SCHEMA.ROUTINES So the insert_user verify script looks like this:

-- Verify insert_user

  sqitch.verify "SELECT COUNT(*) FROM INFORMATION_SCHEMA.ROUTINES WHERE
  ROUTINE_SCHEMA = 'dbo' AND ROUTINE_NAME = 'insert_user'
  AND ROUTINE_DEFINITION like '%CURRENT_TIMESTAMP%';

Make sure these pass by re-deploying:

> sqitch deploy
Deploying changes to flipr_test
  + insert_user .. ok

Excellent. Let's go ahead and commit this change:

> git add .
> git commit -m "Use current_timestamp."
[master abcce73] Use current_timestamp.
 13 files changed, 137 insertions(+), 9 deletions(-)

 create mode 100644 deploy/[email protected]
 create mode 100644 revert/[email protected]
 create mode 100644 verify/[email protected]

> sqitch status
# On database flipr_test
# Project:  flipr
# Change:   6f2e1cd4b1c031a66930811328cfcdb0389d8320
# Name:     insert_user
# Deployed: 2013-12-31 14:16:45 -0800
# By:       Marge N. O’Vera <[email protected]>
# 
Nothing to deploy (up-to-date)

Support for different DBI drivers

ATM it works with DBD::ODBC and has experimental support for DBD::ADO and DBD::Sybase (same as "dbi_dsn" in URI::db::mssql).

If you have problems w/ one of them in use simply install DBD::ODBC and it will be used instead.

In order to ensure support for all 3 drivers:

  • registry_uri() needs the TODO: is this correct for all 3 $self-dbd_driver()?> comment addressed

  • optional/YAGNI?: create a config option to specify the driver

If you have experience w/ DBD::ADO or DBD::Sybase feel free to participate!

sqlcmd.exe/sqlcmd Caveat

To run this on non-Windows machines you will need Microsoft’s sqlcmd utility installed in your path.

More information can be found at https://msdn.microsoft.com/en-us/library/hh568451.aspx.

More to Come

Sqitch is a work in progress. Better integration with version control systems is planned to make managing idempotent reworkings even easier. Stay tuned.

Author

David E. Wheeler <[email protected]>

License

Copyright (c) 2012-2014 iovation Inc.

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.