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sqitchtutorial-firebirUser Contributed Perl Documentsqitchtutorial-firebird(3)

Name
       sqitchtutorial-firebird - A tutorial introduction to Sqitch change
       management on Firebird

Synopsis
	 sqitch	*

Description
       This tutorial explains how to create a sqitch-enabled Firebird 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
       <http://git-scm.com/> as	the VCS	and Firebird
       <http://www.firebirdsql.org/> 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 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/
	 > touch README.md
	 > git add .
	 > git commit -am 'Initialize project, add README.'
	 [master (root-commit) 761ffcd]	Initialize project, add	README.
	  1 files changed, 39 insertions(+), 0 deletions(-)
	  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
       <https://github.com/theory/sqitch-firebird-intro>.

       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 init flipr --uri https://github.com/theory/sqitch-firebird-intro/ --engine firebird
	 Created sqitch.conf
	 Created sqitch.plan
	 Created deploy/
	 Created revert/
	 Created verify/

       Let's have a look at sqitch.conf:

	 > cat sqitch.conf
	 [core]
	       engine =	firebird
	       # plan_file = sqitch.plan
	       # top_dir = .
	 # [engine "firebird"]
	       # target	= db:firebird:
	       # registry = sqitch
	       # client	= isql-fb

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

       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.

       The current implementation of the engine	will try to find Firebird's
       "firebird" client <http://www.firebirdsql.org/manual/isql-
       commands.html> (implemented for GNU/Linux and Microsoft Windows).  This
       might fail, so we go ahead an tell it where to find the client on our
       computer, for example on	GNU/Linux with the standard location of	the
       Firebird	installation the command is:

	 > sqitch config --user	engine.firebird.client /opt/firebird/bin/isql

       Note: On	some GNU/Linux distributions the firebird client is renamed to
       "isql-fb", for example in Debian	and Fedora, or "fbsql" in Gentoo.

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

	 > sqitch config --user	user.name 'Marge N. OXVera'
	 > sqitch config --user	user.email 'marge@example.com'

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

	 > cat ~/.sqitch/sqitch.conf
	 [engine "firebird"]
	   client = /opt/local/bin/isql
	 [user]
	   name	= Marge	N. OXVera
	   email = marge@example.com

       Which means that	Sqitch should be able to find "isql" 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:

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

       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 2177ce4] Initialize Sqitch configuration.
	  2 files changed, 19 insertions(+), 0 deletions(-)
	  create mode 100644 sqitch.conf
	  create mode 100644 sqitch.plan

       Let's create our	flipr test database using "isql":

	 > sudo	-u firebird mkdir /tmp/flipr_test
	 > echo	"CREATE	DATABASE 'localhost:/tmp/flipr_test/flipr.fdb';	exit;" \
	   | isql-fb -q	-u SYSDBA -p masterkey

Our First Change
       Let's create a table. Our app will need users, of course, so we'll
       create a	table for them.	Run this command:

	 > sqitch add users -n 'Creates	table to track our users.'
	 Created deploy/users.sql
	 Created revert/users.sql
	 Created verify/users.sql
	 Added "users" 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/users.sql file looks like this:

	 -- Deploy flipr:users to firebird

	 -- XXX	Add DDLs here.

	 COMMIT;

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

	 -- Deploy flipr:users to firebird

	 CREATE	TABLE users (
	     nickname	VARCHAR(50)  PRIMARY KEY,
	     password	VARCHAR(512) NOT NULL,
	     fullname	VARCHAR(512) NOT NULL,
	     twitter	VARCHAR(512) NOT NULL,
	     created_at	TIMESTAMP    DEFAULT CURRENT_TIMESTAMP NOT NULL
	 );

	 COMMIT;

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

	 -- Revert flipr:users from firebird

	 DROP TABLE users;

	 COMMIT;

       Now we can try deploying	this change:

	 > sqitch deploy db:firebird://sysdba:masterkey@localhost//tmp/flipr_test/flipr.fdb
	 Adding	registry tables	to db:firebird://sysdba:@localhost//tmp/flipr_test/sqitch.fdb
	 Deploying changes to db:firebird://sysdba:@localhost//tmp/flipr_test/flipr.fdb
	   + users .. ok

       First Sqitch created the	registry database and tables used to track
       database	changes. The registry is separate from the database to which
       the "users" change was deployed;	by default, its	name is
       "sqitch.$suffix", where $suffix is the same as the suffix on the	target
       database, if any. It lives in the same directory	as the target
       database, which means that one registry database	is used	for all	the
       databases with the same suffix in a single directory.

       Next, Sqitch deploys changes to the target database. We only have one
       change so far; the "+" reinforces the idea that the change is being
       added to	the database.

       If you'd	like it	to have	a different name for the registry database,
       use "sqitch engine add firebird $name" to configure it (or via the
       "target"	command; more below). This will	be useful if you don't want to
       use the same registry database to manage	multiple databases, or if you
       do, but they live in different directories.

       Next, Sqitch deploys changes to the target database, which we specified
       on the command-line. We only have one 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 "users" table:

	 > echo	"CONNECT 'localhost:/tmp/flipr_test/flipr.fdb';	SHOW TABLES; quit;" \
	   | isql-fb -q	-u SYSDBA -p masterkey
	      USERS

   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 easiest way to do that with a	table
       is to simply "SELECT" from it. Put this query into verify/users.sql:

	 SELECT	nickname, password, fullname, twitter
	   FROM	users
	  WHERE	1=2;

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

	 > sqitch verify db:firebird://sysdba:masterkey@localhost//tmp/flipr_test/flipr.fdb
	 Verifying db:firebird://sysdba:@localhost//tmp/flipr_test/flipr.fdb
	   * users .. 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 table name in
       the script to something that doesn't exist, something like:

	 SELECT	nickname, password, fullname, twitter, created_at
	   FROM	users_nonesuch
	  WHERE	1=2;

       Then "verify" again:

	 > sqitch verify db:firebird://sysdba:masterkey@localhost//tmp/flipr_test/flipr.fdb
	 Verifying db:firebird://sysdba:@localhost//tmp/flipr_test/flipr.fdb
	   * users .. Statement	failed,	SQLSTATE = 42S02
	 Dynamic SQL Error
	 -SQL error code = -204
	 -Table	unknown
	 -USERS_NONESUCH
	 -At line 3, column 2
	 At line 3 in file verify/users.sql
	 # Verify script "verify/users.sql" failed.
	 not ok

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

       Firebird	is kind	enough to tell us what the problem is. 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 db:firebird://sysdba:masterkey@localhost//tmp/flipr_test/flipr.fdb
	 # On database db:firebird://sysdba:@localhost//tmp/flipr_test/flipr.fdb
	 # Project:  flipr
	 # Change:   2cde9cc8c19161e9837de57741502243b2ad380e
	 # Name:     users
	 # Deployed: 2014-01-05	14:05:22 -0800
	 # By:	     Marge N. OXVera <marge@example.com>
	 #
	 Nothing to deploy (up-to-date)

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

	 > sqitch revert db:firebird://sysdba:masterkey@localhost//tmp/flipr_test/flipr.fdb
	 Revert	all changes from db:firebird://sysdba:@localhost//tmp/flipr_test/flipr.fdb? [Yes]
	   - users .. 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 "users" table should be gone:

	 > echo	"CONNECT 'localhost:/tmp/flipr_test/flipr.fdb';	SHOW TABLES; quit;" \
	   | isql-fb -q	-u SYSDBA -p masterkey
	 There are no tables in	this database

       And the status message should reflect as	much:

	 > sqitch status db:firebird://sysdba:masterkey@localhost//tmp/flipr_test/flipr.fdb
	 # On database db:firebird://sysdba:@localhost//tmp/flipr_test/flipr.fdb
	 No changes deployed

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

	 > sqitch verify db:firebird://sysdba:masterkey@localhost//tmp/flipr_test/flipr.fdb
	 Verifying db:firebird://sysdba:@localhost//tmp/flipr_test/flipr.fdb
	 No changes deployed

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

	 > sqitch log db:firebird://sysdba:masterkey@localhost//tmp/flipr_test/flipr.fdb
	 On database db:firebird://sysdba:@localhost//tmp/flipr_test/flipr.fdb
	 Revert	2cde9cc8c19161e9837de57741502243b2ad380e
	 Name:	    users
	 Committer: Marge N. OXVera <marge@example.com>
	 Date:	    2014-01-05 14:06:59	-0800

	     Creates table to track our	users.

	 Deploy	2cde9cc8c19161e9837de57741502243b2ad380e
	 Name:	    users
	 Committer: Marge N. OXVera <marge@example.com>
	 Date:	    2014-01-05 14:05:22	-0800

	     Creates table to track our	users.

       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 users table.'
	 [master ec72105] Add users table.
	  4 files changed, 24 insertions(+), 0 deletions(-)
	  create mode 100644 deploy/users.sql
	  create mode 100644 revert/users.sql
	  create mode 100644 verify/users.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 db:firebird://sysdba:masterkey@localhost//tmp/flipr_test/flipr.fdb --verify
	 Deploying changes to db:firebird://sysdba:@localhost//tmp/flipr_test/flipr.fdb
	   + users .. ok

       And now the "users" table should	be back:

	 > echo	"CONNECT 'localhost:/tmp/flipr_test/flipr.fdb';	SHOW TABLES; quit;" \
	   | isql-fb -q	-u SYSDBA -p masterkey
		USERS

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

	 > sqitch status db:firebird://sysdba:masterkey@localhost//tmp/flipr_test/flipr.fdb
	 # On database db:firebird://sysdba:@localhost//tmp/flipr_test/flipr.fdb
	 # Project:  flipr
	 # Change:   2cde9cc8c19161e9837de57741502243b2ad380e
	 # Name:     users
	 # Deployed: 2014-01-05	14:19:32 -0800
	 # By:	     Marge N. OXVera <marge@example.com>
	 #
	 Nothing to deploy (up-to-date)

On Target
       I'm getting a little tired of always having to type
       "db:firebird://sysdba:masterkey@localhost//tmp/flipr_test/flipr.fdb",
       aren't you? This	database connection URI
       <https://github.com/theory/uri-db/> tells Sqitch	how to connect to the
       deployment target, but we don't have to keep using the URI. We can name
       the target:

	 > sqitch target add flipr_test	db:firebird://sysdba:masterkey@localhost//tmp/flipr_test/flipr.fdb

       The "target" command, inspired by "git-remote" <http://git-
       scm.com/docs/git-remote>, allows	management of one or more named
       deployment targets. We've just added a target named "flipr_test", which
       means we	can use	the string "flipr_test"	for the	target,	rather than
       the URI.	But since we're	doing so much testing, we can also tell	Sqitch
       to deploy to the	"flipr_test" target by default:

	 > sqitch engine add firebird target flipr_test

       Now we can omit the target argument altogether, unless we need to
       deploy to another database. Which we will, eventually, but at least our
       examples	will be	simpler	from here on in, e.g.:

	 > sqitch status
	 # On database flipr_test
	 # Project:  flipr
	 # Change:   2cde9cc8c19161e9837de57741502243b2ad380e
	 # Name:     users
	 # Deployed: 2014-01-05	14:19:32 -0800
	 # By:	     Marge N. OXVera <marge@example.com>
	 #
	 Nothing to deploy (up-to-date)

       Yay, that allows	things to be a little more concise. Let's also make
       sure that changes are verified after deploying them:

	 > sqitch config --bool	deploy.verify true
	 > sqitch config --bool	rebase.verify true

       We'll see the "rebase" command a	bit later. In the meantime, let's
       commit the new configuration and	and make some more changes!

	 > git commit -am 'Set default target and always verify.'
	 [master cfc9fea] Set default target and always	verify.
	  1 files changed, 8 insertions(+), 0 deletions(-)

Deploy with Dependency
       Let's add another change. Our app will need to store status messages
       from users. Let's call them -- and the table to store them -- "flips".
       First, add the new change:

	 > sqitch add flips --requires users -n	'Adds table for	storing	flips.'
	 Created deploy/flips.sql
	 Created revert/flips.sql
	 Created verify/flips.sql
	 Added "flips [users]" to sqitch.plan

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

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

	 -- Deploy flipr:flips to firebird
	 -- requires: users

	 CREATE	TABLE flips (
	     id		INTEGER	      NOT NULL PRIMARY KEY,
	     nickname	VARCHAR(50)   NOT NULL REFERENCES users(nickname),
	     body	VARCHAR(512)  DEFAULT '' NOT NULL CHECK	( char_length(body) <= 180 ),
	     created_at	TIMESTAMP     DEFAULT CURRENT_TIMESTAMP	NOT NULL
	 );

	 COMMMIT;

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

       The "users.nickname" column references the "users" table. This is why
       we need to require the "users" change.

       Now for the verify script. Again, all we	need to	do is "SELECT" from
       the table. I recommend selecting	each column by name, too, to be	sure
       that no column is missing. Here's the verify/flips.sql:

	 -- Verify flipr:flips on firebird

	 SELECT	id, nickname, body, created_at
	   FROM	flips
	   WHERE 1=2;

	 ROLLBACK;

       Now for the revert script: all we have to do is drop the	table. Add
       this to revert/flips.sql:

	 -- Revert flipr:flips from firebird

	 DROP TABLE flips;

	 COMMIT;

       Couldn't	be much	simpler, right?	Let's deploy this bad boy:

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

       We know,	since verification is enabled, that the	table must have	been
       created.	 But for the purposes of visibility, let's have	a quick	look:

	 > echo	"CONNECT 'localhost:/tmp/flipr_test/flipr.fdb';	SHOW TABLES; quit;" \
	   | isql-fb -q	-u SYSDBA -p masterkey
		FLIPS				       USERS

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

	 > sqitch verify
	 Verifying flipr_test.db
	   * users .. ok
	   * flips .. ok
	 Verify	successful

       Now have	a look at the status:

	 > sqitch status
	 # On database flipr_test
	 # Project:  flipr
	 # Change:   dfe72351c686bd36017a2b586042b5336301e809
	 # Name:     flips
	 # Deployed: 2014-01-05	14:22:33 -0800
	 # By:	     Marge N. OXVera <marge@example.com>
	 #
	 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 users from flipr_test
	   - flips .. 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 caret ("^") tells Sqitch to select	the change prior to
       the last	deployed change. So we revert to "users", 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 "flips" table should be gone but the "users"
       table should still be around:

	 > echo	"CONNECT 'localhost:/tmp/flipr_test/flipr.fdb';	SHOW TABLES; quit;" \
	   | isql-fb -q	-u SYSDBA -p masterkey
	      USERS

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

	 > sqitch status
	 # On database flipr_test
	 # Project:  flipr
	 # Change:   2cde9cc8c19161e9837de57741502243b2ad380e
	 # Name:     users
	 # Deployed: 2014-01-05	14:19:32 -0800
	 # By:	     Marge N. OXVera <marge@example.com>
	 #
	 Undeployed change:
	   * flips

       As does the "verify" command:

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

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

       Okay, let's commit and deploy again:

	 > git add .
	 > git commit -am 'Add flips table.'
	 [master 09c636c] Add flips table.
	  4 files changed, 24 insertions(+), 0 deletions(-)
	  create mode 100644 deploy/flips.sql
	  create mode 100644 revert/flips.sql
	  create mode 100644 verify/flips.sql
	 > sqitch deploy
	 Deploying changes to flipr_test
	   + flips .. ok

       Looks good. Check the status:

	 > sqitch status
	 # On database flipr_test
	 # Project:  flipr
	 # Change:   dfe72351c686bd36017a2b586042b5336301e809
	 # Name:     flips
	 # Deployed: 2014-01-05	14:24:06 -0800
	 # By:	     Marge N. OXVera <marge@example.com>
	 #
	 Nothing to deploy (up-to-date)

View to	a Thrill
       One more	thing to add before we are ready to ship a first beta release.
       Let's create a view that	lists user names with their flips.

	 > sqitch add userflips	--requires users --requires flips \
	   -n 'Creates the userflips view.'
	 Created deploy/userflips.sql
	 Created revert/userflips.sql
	 Created verify/userflips.sql
	 Added "userflips [users flips]" to sqitch.plan

       Now add this SQL	to deploy/userflips.sql:

	 CREATE	OR ALTER VIEW userflips	AS
	 SELECT	f.id, u.nickname, u.fullname, f.body, f.created_at
	   FROM	users u
	   JOIN	flips f	ON u.nickname =	f.nickname;

       Add this	SQL to verify/userflips.sql

	 SELECT	id, nickname, fullname,	body, created_at
	   FROM	userflips
	  WHERE	1=2;

       And add the "DROP VIEW" statement to revert/userflips.sql:

	 DROP VIEW userflips;

       Now Try it out!

	 > sqitch deploy
	 Deploying changes to flipr_test
	   + userflips .. ok
	 > sqitch revert -y
	 Reverting all changes from flipr_test
	   - userflips .. ok
	   - flips ...... ok
	   - users ...... ok
	 > sqitch deploy
	 Deploying changes to flipr_test
	   + users ...... ok
	   + flips ...... ok
	   + userflips .. ok

       Looks good! Commit it.

	 > git add .
	 > git commit -m 'Add the userflips view.'
	 [master 28ffa63] Add the userflips view.
	  4 files changed, 23 insertions(+), 0 deletions(-)
	  create mode 100644 deploy/userflips.sql
	  create mode 100644 revert/userflips.sql
	  create mode 100644 verify/userflips.sql

Ship It!
       Now we're ready for the first development 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 -n 'Tag v1.0.0-dev1.'
	 Tagged	"userflips" with @v1.0.0-dev1
	 > git commit -am 'Tag the database with v1.0.0-dev1.'
	 [master 696a891] Tag the database with	v1.0.0-dev1.
	  1 files changed, 1 insertions(+), 0 deletions(-)
	 > git tag v1.0.0-dev1 -am 'Tag	v1.0.0-dev1'

       We can try deploying to make sure the tag gets picked up	like so:

	 > sudo	-u firebird mkdir /tmp/flipr_dev
	 > echo	"CREATE	DATABASE 'localhost:/tmp/flipr_dev/flipr.fdb'; exit;" \
	   | isql-fb -q	-u SYSDBA -p masterkey
	 > sqitch deploy db:firebird://sysdba:masterkey@localhost//tmp/flipr_dev/flipr.fdb
	 Adding	registry tables	to db:firebird://sysdba:@localhost//tmp/flipr_dev/sqitch.fdb
	 Deploying changes to db:firebird://sysdba:@localhost//tmp/flipr_dev/flipr.fdb
	   + users ................... ok
	   + flips ................... ok
	   + userflips @v1.0.0-dev1 .. ok

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

	 > sqitch status db:firebird://sysdba:masterkey@localhost//tmp/flipr_dev/flipr.fdb
	 # On database db:firebird://sysdba:@localhost//tmp/flipr_dev/flipr.fdb
	 # Project:  flipr
	 # Change:   785a0d14a5e26b2ae24882a137db45d34f71b5ff
	 # Name:     userflips
	 # Tag:	     @v1.0.0-dev1
	 # Deployed: 2014-01-05	14:43:28 -0800
	 # By:	     Marge N. OXVera <marge@example.com>
	 #
	 Nothing to deploy (up-to-date)

       Note the	listing	of the tag as part of the status message. Now let's
       bundle everything up for	release:

	 > sqitch bundle
	 Bundling into bundle
	 Writing config
	 Writing plan
	 Writing scripts
	   + users
	   + flips
	   + userflips @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 it:

	 > cd bundle
	 > sudo	-u firebird mkdir /tmp/flipr_prod
	 > echo	"CREATE	DATABASE 'localhost:/tmp/flipr_prod/flipr.fdb';	exit;" \
	   | isql-fb -q	-u SYSDBA -p masterkey
	 > sqitch deploy db:firebird://sysdba:masterkey@localhost//tmp/flipr_prod/flipr.fdb
	 Adding	registry tables	to db:firebird://sysdba:@localhost//tmp/flipr_prod/sqitch.fdb
	 Deploying changes to db:firebird://sysdba:@localhost//tmp/flipr_prod/flipr.fdb
	   + users ................... ok
	   + flips ................... ok
	   + userflips @v1.0.0-dev1 .. ok

       Looks much the same as before, eh? Package it up	and ship it!

	 > cd ..
	 > mv bundle flipr-v1.0.0-dev1
	 > tar -czf flipr-v1.0.0-dev1.tgz flipr-v1.0.0-dev1

Making a Hash of Things
       Now that	we've got the basics of	the app	done, let's add	a feature.
       Gotta track the hashtags	associated with	flips, right? Let's add	a
       table for them.	But 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 hashtags
	 Switched to a new branch 'hashtags'

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

	 > sqitch add hashtags --requires flips	-n 'Adds table for storing hashtags.'
	 Created deploy/hashtags.sql
	 Created revert/hashtags.sql
	 Created verify/hashtags.sql
	 Added "hashtags [flips]" to sqitch.plan

       You know	the drill by now. Add this to deploy/hashtags.sql

	 CREATE	TABLE hashtags (
	     flip_id   INTEGER	    NOT	NULL REFERENCES	flips(id),
	     hashtag   VARCHAR(512) NOT	NULL CHECK(char_length(hashtag)	> 0),
	     PRIMARY KEY (flip_id, hashtag)
	 );

       Again, select from the table in verify/hashtags.sql:

	 SELECT	flip_id, hashtag FROM hashtags WHERE 1=2;

       And drop	it in revert/hashtags.sql

	 DROP TABLE hashtags;

       And give	it a whirl:

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

       Look good?

	 > sqitch status --show-tags
	 # On database flipr_test
	 # Project:  flipr
	 # Change:   9474af3b057294633ccf81b9e8d7771a9588ac67
	 # Name:     hashtags
	 # Deployed: 2014-01-05	14:55:56 -0800
	 # By:	     Marge N. OXVera <marge@example.com>
	 #
	 # Tag:
	 #   @v1.0.0-dev1 - 2014-01-05 14:49:56	-0800 -	Marge N. OXVera	<marge@example.com>
	 #
	 Nothing to deploy (up-to-date)

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

	 > rm -rf flipr-v1.0.0-dev1*
	 > git add .
	 > git commit -am 'Add hashtags	table.'
	 [hashtags 9c40bf5] Add	hashtags table.
	  4 files changed, 22 insertions(+), 0 deletions(-)
	  create mode 100644 deploy/hashtags.sql
	  create mode 100644 revert/hashtags.sql
	  create mode 100644 verify/hashtags.sql

       Good, we've finished this feature. Time to merge	back into "master".

   Emergency
       Let's do	it:

	 > git checkout	master
	 Switched to branch 'master'
	 > git pull
	 Updating 696a891..9af80a1
	 Fast-forward
	  deploy/lists.sql |   11 +++++++++++
	  revert/lists.sql |	5 +++++
	  sqitch.plan	   |	2 ++
	  verify/lists.sql |	7 +++++++
	  4 files changed, 25 insertions(+), 0 deletions(-)
	  create mode 100644 deploy/lists.sql
	  create mode 100644 revert/lists.sql
	  create mode 100644 verify/lists.sql

       Hrm, that's interesting.	Looks like someone made	some changes to
       "master".  They added list support. Well, let's see what	happens	when
       we merge	our changes.

	 > git merge --no-ff hashtags
	 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 "hashtags"	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:

       o   Rebase the hashtags 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.

       o   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	d5e7e86	Merge branch 'lists'

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

	 > git checkout	hashtags
	 Switched to branch 'hashtags'
	 > git rebase master
	 First,	rewinding head to replay your work on top of it...
	 Applying: Add hashtags	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 hashtags 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 <http://git-
       scm.com/docs/gitattributes#_built-in_merge_drivers>:

	   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 hashtags	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

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

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

	 users 2014-01-05T22:01:30Z Marge N. OXVera <marge@example.com>	# Creates table	to track our users.
	 flips [users] 2014-01-05T22:21:24Z Marge N. OXVera <marge@example.com>	# Adds table for storing flips.
	 userflips [users flips] 2014-01-05T22:40:29Z Marge N. OXVera <marge@example.com> # Creates the	userflips view.
	 @v1.0.0-dev1 2014-01-05T22:42:36Z Marge N. OXVera <marge@example.com> # Tag v1.0.0-dev1.

	 lists [flips] 2014-01-05T22:44:41Z Marge N. OXVera <marge@example.com>	# Adds table for storing lists.
	 hashtags [flips] 2014-01-05T22:54:27Z Marge N.	OXVera <marge@example.com> # Adds table	for storing hashtags.

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

	 > sqitch rebase -y
	 Reverting all changes from flipr_test
	   - hashtags ................ ok
	   - userflips @v1.0.0-dev1 .. ok
	   - flips ................... ok
	   - users ................... ok
	 Deploying changes to flipr_test
	   + users ................... ok
	   + flips ................... ok
	   + userflips @v1.0.0-dev1 .. ok
	   + lists ................... ok
	   + hashtags ................ 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`.'
	 [hashtags 52ed9a2] Add	`.gitattributes` with union merge for `sqitch.plan`.
	  1 files changed, 1 insertions(+), 0 deletions(-)
	  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 hashtags -m "Merge	branch 'hashtags'"
	 Merge made by recursive.
	  .gitattributes      |	   1 +
	  deploy/hashtags.sql |	  10 ++++++++++
	  revert/hashtags.sql |	   5 +++++
	  sqitch.plan	      |	   1 +
	  verify/hashtags.sql |	   5 +++++
	  5 files changed, 22 insertions(+), 0 deletions(-)
	  create mode 100644 .gitattributes
	  create mode 100644 deploy/hashtags.sql
	  create mode 100644 revert/hashtags.sql
	  create mode 100644 verify/hashtags.sql

       And double-check	our work:

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

	 users 2014-01-05T22:01:30Z Marge N. OXVera <marge@example.com>	# Creates table	to track our users.
	 flips [users] 2014-01-05T22:21:24Z Marge N. OXVera <marge@example.com>	# Adds table for storing flips.
	 userflips [users flips] 2014-01-05T22:40:29Z Marge N. OXVera <marge@example.com> # Creates the	userflips view.
	 @v1.0.0-dev1 2014-01-05T22:42:36Z Marge N. OXVera <marge@example.com> # Tag v1.0.0-dev1.

	 lists [flips] 2014-01-05T22:44:41Z Marge N. OXVera <marge@example.com>	# Adds table for storing lists.
	 hashtags [flips] 2014-01-05T22:54:27Z Marge N.	OXVera <marge@example.com> # Adds table	for storing hashtags.

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

	 > sqitch tag v1.0.0-dev2 -n 'Tag v1.0.0-dev2.'
	 Tagged	"hashtags" with	@v1.0.0-dev2
	 > git commit -am 'Tag the database with v1.0.0-dev2.'
	 [master 7d07ee3] 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
	   + users
	   + flips
	   + userflips @v1.0.0-dev1
	   + lists
	   + hashtags @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
       Well, some folks	have been testing the "1.0.0-dev2" release and have
       demanded	that Twitter user links	be added to Flipr pages. Why anyone
       would want to include social network links in an	anti-social networking
       app is beyond us	programmers, but we're just the	plumbers, right? Gotta
       go with what Marketing demands. The upshot is that we need to update
       the "userflips" view, which is used for the feature in question,	to
       include the Twitter user	names.

       Normally, modifying views in database changes is	a PITA
       <http://www.urbandictionary.com/define.php?term=pita>. You have to make
       changes like these:

       1.  Copy	deploy/userflips.sql to	deploy/userflips_twitter.sql.

       2.  Edit	deploy/userflips_twitter.sql to	re-create the view with	the
	   new "twitter" column	added to the view.

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

       4.  Add a "DROP VIEW" statement to revert/userflips_twitter.sql.

       5.  Copy	verify/userflips.sql to	verify/userflips_twitter.sql.

       6.  Modify verify/userflips_twitter.sql to include a check for the
	   "twiter" column.

       7.  Test	the changes to make sure you can deploy	and revert the
	   "userflips_twitter" change.

       But you can have	Sqitch do most of the work 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 userflips -n 'Adds userflips.twitter.'
	 Added "userflips [userflips@v1.0.0-dev2]" to sqitch.plan.
	 Modify	these files as appropriate:
	   * deploy/userflips.sql
	   * revert/userflips.sql
	   * verify/userflips.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	"userflips" change, which we can see via "git
       status":

	 > git status
	 # On branch master
	 # Your	branch is ahead	of 'origin/master' by 4	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/userflips.sql
	 #     modified:   sqitch.plan
	 #
	 # Untracked files:
	 #   (use "git add <file>..." to include in what will be committed)
	 #
	 #     deploy/userflips@v1.0.0-dev2.sql
	 #     revert/userflips@v1.0.0-dev2.sql
	 #     verify/userflips@v1.0.0-dev2.sql
	 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 "userflips@v1.0.0-dev2.sql". What that means is:
       "the "userflips"	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 "userflips" 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/userflips.sql has changed.
       Sqitch replaced it with the original deploy script. As of now,
       deploy/userflips.sql and	revert/userflips.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.

       Fortunately, our	view deploy scripts are	already	almost idempotent
       <http://en.wikipedia.org/wiki/Idempotence> -- 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/userflips@v1.0.0-dev2.sql.

       Fortunately, our	view deploy scripts are	already	idempotent, thanks to
       the use of the "OR ALTER" expression. No	matter how many	times a
       deployment script is run, the end result	will be	the same instance of
       the view, with no duplicates or errors.

       As a result, there is no	need to	explicitly add changes.	So go ahead.
       Modify deploy/userflips.sql to add the "twitter"	column.

	 @@ -3,7 +3,7 @@
	  -- requires: flips

	  CREATE OR ALTER VIEW userflips AS
	 -SELECT f.id, u.nickname, u.fullname, f.body, f.created_at
	 +SELECT f.id, u.nickname, u.fullname, u.twitter, f.body, f.created_at
	    FROM users u
	    JOIN flips f ON u.nickname = f.nickname;

       Next, modify verify/userflips.sql to check for the "twitter" column.
       Here's the diff:

	 @@ -1,6 +1,6 @@
	  -- Verify flipr:userflips on firebird

	 -SELECT id, nickname, fullname, body, created_at
	 +SELECT id, nickname, twitter,	fullname, body,	created_at
	    FROM userflips
	   WHERE 1=2;

       Now try a deployment:

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

       So, are the changes deployed?

	 > echo	"CONNECT 'localhost:/tmp/flipr_test/flipr.fdb';	SHOW VIEW userflips; quit;" \
	   | isql-fb -q	-u SYSDBA -p masterkey
	 ID				 INTEGER Not Null
	 NICKNAME			 VARCHAR(50) Not Null
	 FULLNAME			 VARCHAR(512) Not Null
	 TWITTER			 VARCHAR(512) Not Null
	 BODY				 VARCHAR(512) Not Null
	 CREATED_AT			 TIMESTAMP Not Null
	 View Source:
	 ==== ======

	 SELECT	f.id, u.nickname, u.fullname, u.twitter, f.body, f.created_at
	   FROM	users u
	   JOIN	flips f	ON u.nickname =	f.nickname

       Awesome,	the view now includes the "twitter" column. But	can we revert?

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

       Did that	work, is the "twitter" column gone?

	 > echo	"CONNECT 'localhost:/tmp/flipr_test/flipr.fdb';	SHOW VIEW userflips; quit;" \
	   | isql-fb -q	-u SYSDBA -p masterkey
	 ID				 INTEGER Not Null
	 NICKNAME			 VARCHAR(50) Not Null
	 FULLNAME			 VARCHAR(512) Not Null
	 BODY				 VARCHAR(512) Not Null
	 CREATED_AT			 TIMESTAMP Not Null
	 View Source:
	 ==== ======

	 SELECT	f.id, u.nickname, u.fullname, f.body, f.created_at
	   FROM	users u
	   JOIN	flips f	ON u.nickname =	f.nickname

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

       Excellent. Let's	go ahead and commit these changes:

	 > rm -rf flipr-1.0.0-dev2
	 > git add .
	 > git commit -m 'Add the twitter column to the	userflips view.'
	 [master f530359] Add the twitter column to the	userflips view.
	  7 files changed, 32 insertions(+), 4 deletions(-)
	  create mode 100644 deploy/userflips@v1.0.0-dev2.sql
	  create mode 100644 revert/userflips@v1.0.0-dev2.sql
	  create mode 100644 verify/userflips@v1.0.0-dev2.sql

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.

Authors
       o   Xtefan Suciu	<stefbv70@gmail.com>

       o   David E. Wheeler <david@justatheory.com>

License
       Copyright (c) 2012-2015 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.

perl v5.32.0			  2020-08-29	    sqitchtutorial-firebird(3)

Name | Synopsis | Description | Starting a New Project | Our First Change | On Target | Deploy with Dependency | View to a Thrill | Ship It! | Making a Hash of Things | In Place Changes | More to Come | Authors | License

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