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sqitchtutorial-verticaUser Contributed Perl Documentasqitchtutorial-vertica(3)

Name
       sqitchtutorial-vertica -	A tutorial introduction	to Sqitch change
       management on Vertica

Synopsis
	 sqitch	*

Description
       This tutorial explains how to create a sqitch-enabled Vertica 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 a new project from scratch, a fictional
       antisocial networking site called Flipr.	All examples use Git
       <http://git-scm.com/> as	the VCS	and Vertica <https://my.vertica.com/>
       as the storage engine, but for the most part you	can substitute other
       VCSes and database engines in the examples as appropriate.

       If you'd	like to	manage an Vertica 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.

   Connection Configuration
       Sqitch requires ODBC to connect to the Vertica database.	As such,
       you'll need to make sure	that the Vertica ODBC driver is	properly
       configured. At its simplest, on Unix-like systems, name the driver
       "Vertica" by adding this	entry to "odbcainst.ini" (usually found	in
       "/etc", "/usr/etc", or "/usr/local/etc"):

	 [Vertica]
	 Description = ODBC for	Vertica
	 Driver	     = /opt/vertica/lib64/libverticaodbc.so

       And also	creating a "vertica.ini" file in the same directory that
       contains:

	 [Driver]
	 DriverManagerEncoding=UTF-16
	 ODBCInstLib=/usr/lib64/libodbcinst.so
	 ErrorMessagesPath=/opt/vertica/lib64

       You might also consider naming your database connection by putting an
       entry in	"odbc.ini" (same directory), like so (assuming that Vertica is
       running on your local host):

	 [dbadmin]
	 Description = Vertica dbadmin connection
	 Driver	= Vertica
	 Database = dbadmin
	 Servername = localhost
	 UserName = dbadmin
	 Password = password
	 Port =	5433
	 Locale	= en_US

       See the Vertica ODBC Documentation
       <http://my.vertica.com/docs/7.1.x/HTML/index.htm#Authoring/ConnectingToHPVertica/InstallingDrivers/CreatingAnODBCDataSourceNameDSN.htm>
       for details. Specific links:

       o   Unix	ODBC Configuration
	   <http://my.vertica.com/docs/7.1.x/HTML/index.htm#Authoring/ConnectingToHPVertica/InstallingDrivers/CreatingAnODBCDSNForLinuxSolarisAIXAndHP-
	   UX.htm>

       o   Additional Linux ODBC Configuration ("vertica.ini")
	   <http://my.vertica.com/docs/7.1.x/HTML/index.htm#Authoring/ConnectingToHPVertica/ClientODBC/AdditionalODBCDriverConfigurationSettings.htm>

       o   Windows ODBC	Configuration
	   <http://my.vertica.com/docs/7.1.x/HTML/index.htm#Authoring/ConnectingToHPVertica/InstallingDrivers/CreatingAnODBCDSNForWindowsClients.htm>

       o   Mac OS X ODBC Configuration
	   <http://my.vertica.com/docs/7.1.x/HTML/index.htm#Authoring/ConnectingToHPVertica/InstallingDrivers/CreatingAnODBCDSNForMacintoshOSXClients.htm>

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.'

       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-vertica-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-vertica-intro/ --engine vertica
	 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 =	vertica
	       # plan_file = sqitch.plan
	       # top_dir = .
	 # [engine "vertica"]
	       # target	= db:vertica:
	       # registry = sqitch
	       # client	= vsql

       Good, it	picked up on the fact that we're creating changes for the
       Vertica engine, thanks to the "-engine vertica" option, and saved it to
       the file. Furthermore, it wrote a commented-out "[engine	"vertica"]"
       section with all	the available Vertica 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. Since Vertica's "vsql"	client is not in the path on my
       system, let's go	ahead an tell it where to find the client on our
       computer:

	 > sqitch config --user	engine.vertica.client /opt/vertica/bin/vsql

       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 this:

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

       Which means that	Sqitch should be able to find "vsql" 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-vertica-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 a42564d] Initialize Sqitch configuration.
	  2 files changed, 16 insertions(+), 0 deletions(-)
	  create mode 100644 sqitch.conf
	  create mode 100644 sqitch.plan

Our First Change
       First, our project will need a schema. This creates a nice namespace
       for all of the objects that will	be part	of the flipr app. Run this
       command:

	 > sqitch add appschema	-n 'Add	schema for all flipr objects.'
	 Created deploy/appschema.sql
	 Created revert/appschema.sql
	 Created verify/appschema.sql
	 Added "appschema" 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 schema. So we add
       this to deploy/appschema.sql:

	 CREATE	SCHEMA flipr;

       The "revert" script's job is to precisely revert	the change to the
       deploy script, so we add	this to	revert/appschema.sql:

	 DROP SCHEMA flipr;

       Now we can try deploying	this change. We	tell Sqitch where to send the
       change via a database URI <https://github.com/theory/uri-db/>, assuming
       the default "dbadmin" database and user and an ODBC driver named
       "Vertica" (see "Connection Configuration" for details):

	 > sqitch deploy db:vertica://dbadmin:password@localhost:5433/dbadmin?Driver=Vertica
	 Adding	registry tables	to db:vertica://dbadmin:@localhost:5433/dbadmin?Driver=Vertica
	 Deploying changes to db:vertica://dbadmin:@localhost:5433/dbadmin?Driver=Vertica
	   + appschema .. ok

       First Sqitch created registry tables used to track database changes.
       The structure and name of the registry varies between databases
       (Vertica	uses a schema to namespace its registry, while SQLite and
       MySQL use separate databases). Next, Sqitch deploys changes. 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 schema:

	 > vsql	-U dbadmin -c '\dn flipr'
	       List of schemas
	  Name	|  Owner  | Comment
	 -------+---------+---------
	  flipr	| dbadmin |

   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. In Vertica, the simplest way to do so
       for schema is probably to simply	create an object in the	schema.	Put
       this SQL	into verify/appschema.sql:

	 CREATE	TABLE flipr.verify__ (id int);
	 DROP	TABLE flipr.verify__;

       In truth, you can use any query that generates an SQL error if the
       schema doesn't exist. Another handy way to do that is to	divide by zero
       if an object doesn't exist. For example,	to throw an error when the
       "flipr" schema does not exist, you could	do something like this:

	 SELECT	1/COUNT(*) FROM	v_catalog.schemata WHERE schema_name = 'flipr';

       Either way, run the "verify" script with	the "verify" command:

	 > sqitch verify db:vertica://dbadmin:password@localhost:5433/dbadmin?Driver=Vertica
	 Verifying db:vertica://dbadmin:@localhost:5433/dbadmin?Driver=Vertica
	   * appschema .. ok
	 Verify	successful

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

	 CREATE	TABLE nonesuch.verify__	(id int);

       Then "verify" again:

	 > sqitch verify db:vertica://dbadmin:password@localhost:5433/dbadmin?Driver=Vertica
	 Verifying db:vertica://dbadmin:@localhost:5433/dbadmin?Driver=Vertica
	   * appschema .. vsql:verify/appschema.sql:5: ROLLBACK	4650:  Schema "nonesuch" does not exist
	 # Verify script "verify/appschema.sql"	failed.
	 not ok

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

       It's even nice enough to	tell us	what the problem is. Or, for the
       divide-by-zero example, change the schema name:

	 SELECT	1/COUNT(*) FROM	v_catalog.schemata WHERE schema_name = 'nonesuch';

       Then the	verify will look something like:

	 > sqitch verify db:vertica://dbadmin:password@localhost:5433/dbadmin?Driver=Vertica
	 Verifying db:vertica://dbadmin:@localhost:5433/dbadmin?Driver=Vertica
	   * appschema .. vsql:verify/appschema.sql:5: ERROR 2005:  division by	zero
	 # Verify script "verify/appschema.sql"	failed.
	 not ok

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

       Less useful error output, but enough to alert us	that something has
       gone wrong.

       Don't forget to change the schema 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 registry tables
       from the	database:

	 > sqitch status db:vertica://dbadmin:password@localhost:5433/dbadmin?Driver=Vertica
	 # On database db:vertica://dbadmin:@localhost:5433/dbadmin?Driver=Vertica
	 # Project:  flipr
	 # Change:   f9759f0ed77964b6a3b6c7aa3b6058b4bb7db764
	 # Name:     appschema
	 # Deployed: 2014-09-04	15:26:28 -0700
	 # 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:vertica://dbadmin:password@localhost:5433/dbadmin?Driver=Vertica
	 Revert	all changes from db:vertica://dbadmin:@localhost:5433/dbadmin?Driver=Vertica? [Yes]
	   - appschema .. 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:

	 > vsql	-U dbadmin -c '\dn flipr'
	     List of schemas
	  Name | Owner | Comment
	 ------+-------+---------
	 (0 rows)

       And the status message should reflect as	much:

	 > sqitch status db:vertica://dbadmin:password@localhost:5433/dbadmin?Driver=Vertica
	 # On database db:vertica://dbadmin:@localhost:5433/dbadmin?Driver=Vertica
	 No changes deployed

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

	 > sqitch verify db:vertica://dbadmin:password@localhost:5433/dbadmin?Driver=Vertica
	 Verifying db:vertica://dbadmin:@localhost:5433/dbadmin?Driver=Vertica
	 No changes deployed

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

	 > sqitch log db:vertica://dbadmin:password@localhost:5433/dbadmin?Driver=Vertica
	 On database db:vertica://dbadmin:@localhost:5433/dbadmin?Driver=Vertica
	 Revert	f9759f0ed77964b6a3b6c7aa3b6058b4bb7db764
	 Name:	    appschema
	 Committer: Marge N. OXVera <marge@example.com>
	 Date:	    2014-09-04 16:33:02	-0700

	     Add schema	for all	flipr objects.

	 Deploy	f9759f0ed77964b6a3b6c7aa3b6058b4bb7db764
	 Name:	    appschema
	 Committer: Marge N. OXVera <marge@example.com>
	 Date:	    2014-09-04 15:26:28	-0700

	     Add schema	for all	flipr objects.

       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 flipr schema.'
	 [master 9bee4bd] Add flipr schema.
	  5 files changed, 197 insertions(+), 0	deletions(-)
	  create mode 100644 deploy/appschema.sql
	  create mode 100644 revert/appschema.sql
	  create mode 100644 sqitch.sql
	  create mode 100644 verify/appschema.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 db:vertica://dbadmin:password@localhost:5433/dbadmin?Driver=Vertica
	 Deploying changes to db:vertica://dbadmin:@localhost:5433/dbadmin?Driver=Vertica
	   + appschema .. ok

       And now the schema should be back:

	 > vsql	-U dbadmin -c '\dn flipr'
	       List of schemas
	  Name	|  Owner  | Comment
	 -------+---------+---------
	  flipr	| dbadmin |

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

	 > sqitch status db:vertica://dbadmin:password@localhost:5433/dbadmin?Driver=Vertica
	 # On database db:vertica://dbadmin:@localhost:5433/dbadmin?Driver=Vertica
	 # Project:  flipr
	 # Change:   f9759f0ed77964b6a3b6c7aa3b6058b4bb7db764
	 # Name:     appschema
	 # Deployed: 2014-09-04	16:37:38 -0700
	 # 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:vertica://dbadmin:password@localhost:5433/dbadmin?Driver=Vertica",
       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:vertica://dbadmin:password@localhost:5433/dbadmin?Driver=Vertica

       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 vertica 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:   f9759f0ed77964b6a3b6c7aa3b6058b4bb7db764
	 # Name:     appschema
	 # Deployed: 2014-09-04	16:37:38 -0700
	 # 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 deployment target and always verify.'
	 [master 469779a] Set default deployment target	and always verify.
	  1 files changed, 8 insertions(+), 0 deletions(-)

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 appschema -n 'Creates table to track our	users.'
	 Created deploy/users.sql
	 Created revert/users.sql
	 Created verify/users.sql
	 Added "users [appschema]" to sqitch.plan

       Note that we're requiring the "appschema" 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 flipr:users											to vertica
	 -- requires: appschema

	 CREATE	TABLE flipr.users (
	     nickname  VARCHAR	    PRIMARY KEY,
	     password  VARCHAR	    NOT	NULL,
	     fullname  VARCHAR(256) NOT	NULL,
	     twitter   VARCHAR	    NOT	NULL,
	     timestamp TIMESTAMPTZ  NOT	NULL DEFAULT NOW()
	 );

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

       The table itself	will be	created	in the "flipr" schema. This is why we
       need to require the "appschema" change.

       Now for the verify script. The simplest way to check that the table was
       created and has the expected columns without touching the data? Just
       select from the table with a false "WHERE" clause. Add this to
       verify/users.sql:

	 SELECT	nickname, password, twitter, timestamp
	   FROM	flipr.users
	  WHERE	FALSE;

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

	 DROP TABLE flipr.users;

       Couldn't	be much	simpler, right?	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, let's have	a quick	look:

	 > vsql	-U dbadmin -c '\d flipr.users'
					       List of Fields by Tables
	  Schema | Table |   Column    |    Type     | Size | Default |	Not Null | Primary Key | Foreign Key
	 --------+-------+-------------+-------------+------+---------+----------+-------------+-------------
	  flipr	 | users | nickname    | varchar(80) |	 80 |	      |	t	 | t	       |
	  flipr	 | users | password    | varchar(80) |	 80 |	      |	t	 | f	       |
	  flipr	 | users | "timestamp" | timestamptz |	  8 | now()   |	t	 | f	       |

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

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

       Now have	a look at the status:

	 > sqitch status
	 # On database flipr_test
	 # Project:  flipr
	 # Change:   d647ac8c130a7e0b12c9049789e46afb4a4f6e53
	 # Name:     users
	 # Deployed: 2014-09-04	16:42:45 -0700
	 # 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 appschema	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 caret ("^") tells Sqitch to select	the change prior to
       the last	deployed change. So we revert to "appschema", 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"
       schema should still be around:

	 > vsql	-U dbadmin -c '\d flipr.users'
	 Did not find any relation.

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

	 > sqitch status
	 # On database flipr_test
	 # Project:  flipr
	 # Change:   f9759f0ed77964b6a3b6c7aa3b6058b4bb7db764
	 # Name:     appschema
	 # Deployed: 2014-09-04	16:37:38 -0700
	 # By:	     Marge N. OXVera <marge@example.com>
	 #
	 Undeployed change:
	   * users

       As does the "verify" command:

	 > sqitch verify
	 Verifying flipr_test
	   * appschema .. 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 c7c24c5] Add users table.
	  4 files changed, 18 insertions(+), 0 deletions(-)
	  create mode 100644 deploy/users.sql
	  create mode 100644 revert/users.sql
	  create mode 100644 verify/users.sql
	 Deploying changes to flipr_test
	   + users .. ok

       Looks good. Check the status:

	 > sqitch status
	 # On database flipr_test
	 # Project:  flipr
	 # Change:   d647ac8c130a7e0b12c9049789e46afb4a4f6e53
	 # Name:     users
	 # Deployed: 2014-09-04	17:42:53 -0700
	 # By:	     Marge N. OXVera <marge@example.com>
	 #
	 Nothing to deploy (up-to-date)

       Excellent. Let's	do some	more!

Add Two	at Once
       Let's add a couple more changes.	Our app	will need to store status
       messages	from users. Let's call them -- and the table to	store them --
       "flips".	And we'll also need a view that	lists user names with their
       flips. Let's add	changes	for them both:

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

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

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

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

	 appschema 2014-09-04T18:40:34Z	Marge N. OXVera	<marge@example.com> # Add schema for all flipr objects.
	 users [appschema] 2014-09-04T23:40:15Z	Marge N. OXVera	<marge@example.com> # Creates table to track our users.
	 flips [appschema users] 2014-09-05T00:16:58Z Marge N. OXVera <marge@example.com> # Adds table for storing flips.
	 userflips [appschema users flips] 2014-09-05T00:18:43Z	Marge N. OXVera	<marge@example.com> # Creates the userflips view.

       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/flips.sql
       should look like:

	 -- Deploy flipr:flips to vertica
	 -- requires: appschema
	 -- requires: users

	 CREATE	TABLE flipr.flips (
	     id	       AUTO_INCREMENT PRIMARY KEY ,
	     nickname  VARCHAR	      NOT NULL REFERENCES flipr.users(nickname),
	     body      VARCHAR(180)   NOT NULL DEFAULT '',
	     timestamp TIMESTAMPTZ    NOT NULL DEFAULT clock_timestamp()
	 );

       Here's what verify/flips.sql might look like:

	 -- Verify flipr:flips											on vertica
	 SELECT	id, nickname, body, timestamp
	   FROM	flipr.flips
	  WHERE	FALSE;

       We simply take advantage	of the fact that "has_function_privilege()"
       throws an exception if the specified function does not exist.

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

	 -- Revert flipr:flips from vertica
	 DROP TABLE flipr.flips;

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

	 -- Deploy flipr:userflips to vertica
	 -- requires: appschema
	 -- requires: users
	 -- requires: flips

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

       Use a "SELECT" statement	in verify/userflips.sql	again:

	 -- Verify flipr:userflips on vertica
	 SELECT	id, nickname, fullname,	body, timestamp
	   FROM	flipr.userflips
	  WHERE	FALSE;

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

	 -- Revert flipr:userflips from	vertica
	 DROP VIEW flipr.userflips;

       Try em out!

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

       Do we have the new table	and view? Of course we do, they	were verified.
       Still, have a look:

	 > vsql	-U dbadmin -c '\dt flipr.flips'
			List of	tables
	  Schema | Name	 | Kind	 |  Owner  | Comment
	 --------+-------+-------+---------+---------
	  flipr	 | flips | table | dbadmin |

	 > vsql	-U dbadmin -c '\dv flipr.userflips'
			   List	of View	Fields
	  Schema |   View    |	 Column	   |	 Type	  | Size
	 --------+-----------+-------------+--------------+------
	  flipr	 | userflips | id	   | int	  |    8
	  flipr	 | userflips | nickname	   | varchar(80)  |   80
	  flipr	 | userflips | fullname	   | varchar(256) |  256
	  flipr	 | userflips | body	   | varchar(180) |  180
	  flipr	 | userflips | "timestamp" | timestamptz  |    8

       And what's the status?

	 > sqitch status
	 # On database flipr_test
	 # Project:  flipr
	 # Change:   d1f998618fb863d93049a724fd0d2b49a29add86
	 # Name:     userflips
	 # Deployed: 2014-09-04	17:51:21 -0700
	 # By:	     Marge N. OXVera <marge@example.com>
	 #
	 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
	   - userflips .. ok
	   - flips ...... ok
	 >  vsql -U dbadmin -c '\d flipr.flips'
	 Did not find any relation.
	 > vsql	-U dbadmin -c '\dv flipr.userflips'
	 No matching relations found.

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

	 > git add .
	 > git commit -m 'Add flips table and userflips	view.'
	 [master c40f23f] Add flips table and userflips	view.
	  7 files changed, 41 insertions(+), 0 deletions(-)
	  create mode 100644 deploy/flips.sql
	  create mode 100644 deploy/userflips.sql
	  create mode 100644 revert/flips.sql
	  create mode 100644 revert/userflips.sql
	  create mode 100644 verify/flips.sql
	  create mode 100644 verify/userflips.sql

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

	 > sqitch status
	 # On database flipr_test
	 # Project:  flipr
	 # Change:   d1f998618fb863d93049a724fd0d2b49a29add86
	 # Name:     userflips
	 # Deployed: 2014-09-04	17:59:34 -0700
	 # By:	     Marge N. OXVera <marge@example.com>
	 #
	 Nothing to deploy (up-to-date)

	 > sqitch verify
	 Verifying flipr_test
	   * appschema .. ok
	   * users ...... ok
	   * flips ...... ok
	   * userflips .. 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 -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 b07ce3d] 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:

	 > sqitch deploy
	 Nothing to deploy (up-to-date)
	 > sqitch status
	 # On database flipr_test
	 # Project:  flipr
	 # Change:   d1f998618fb863d93049a724fd0d2b49a29add86
	 # Name:     userflips
	 # Tag:	     @v1.0.0-dev1
	 # Deployed: 2014-09-04	17:59:34 -0700
	 # By:	     Marge N. OXVera <marge@example.com>
	 #
	 Nothing to deploy (up-to-date)

       Note the	new "Tag" line in the output of	"sqitch	status": no new
       changes needed to be deployed, but Sqitch did deploy the	tag on the
       "userflips" change. Now let's bundle everything up for release:

	 > sqitch bundle
	 Bundling into bundle
	 Writing config
	 Writing plan
	 Writing scripts
	   + appschema
	   + 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 to another database:

	 > cd bundle
	 > sqitch deploy db:vertica://dbadmin:password@db.example.com:5433/flipr?Driver=Vertica
	 Adding	registry tables	to db:vertica://dbadmin:@db.example.com:5433/flipr?Driver=Vertica
	 Deploying changes to db:vertica://dbadmin:@db.example.com:5433/flipr?Driver=Vertica
	   + appschema ............... ok
	   + users ................... ok
	   + flips ................... ok
	   + userflips @v1.0.0-dev1 .. ok

       Notice how the tag on "userflips" now appears in	the deploy output.
       Nice, eh?  Now, package it up and ship it!

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:

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 [appschema flips]" to sqitch.plan

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

	 CREATE	TABLE flipr.hashtags (
	     flip_id   BIGINT  NOT   NULL REFERENCES flipr.Flips(id),
	     hashtag   VARCHAR(128)  NOT NULL,
	     PRIMARY KEY (flip_id, hashtag)
	 );

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

	 SELECT	flip_id, hashtag FROM flipr.hashtags WHERE FALSE;

       And drop	it in revert/hashtags.sql

	 DROP TABLE flipr.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:   fda6daef73e0ac12252bf6af5f259ccb207d4197
	 # Name:     hashtags
	 # Deployed: 2014-09-05	10:46:20 -0700
	 # By:	     Marge N. OXVera <marge@example.com>
	 #
	 # Tag:
	 #   @v1.0.0-dev1 - 2014-09-05 09:09:38	-0700 -	Marge N. OXVera	<marge@example.com>
	 #
	 Nothing to deploy (up-to-date)

       Note the	use of "--show tags" to	show all the deployed tags. Make sure
       we can revert, too:

	 > sqitch rebase -y --onto @HEAD^
	 Reverting changes to userflips	@v1.0.0-dev1 from flipr_test
	   - hashtags .. ok
	 Deploying changes to flipr_test
	   + hashtags .. ok

       Great! Now make it so:

	 > git add .
	 > git commit -m 'Add hashtags table.'
	 [hashtags d893e9c] Add	hashtags table.
	  4 files changed, 18 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 b07ce3d..05d3e5d
	 Fast-forward
	  deploy/lists.sql |   10 ++++++++++
	  revert/lists.sql |	3 +++
	  sqitch.plan	   |	2 ++
	  verify/lists.sql |	5 +++++
	  4 files changed, 20 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	05d3e5d	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...
	 <stdin>:16: new blank line at EOF.
	 +
	 warning: 1 line adds whitespace errors.
	 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.

	 When you have resolved	this problem run "git rebase --continue".
	 If you	would prefer to	skip this patch, instead run "git rebase --skip".
	 To restore 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
	 HEAD is now at	d893e9c	Add hashtags table.

       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...
	 <stdin>:16: new blank line at EOF.
	 +
	 warning: 1 line adds whitespace errors.
	 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-vertica-intro/

	 appschema 2014-09-04T18:40:34Z	Marge N. OXVera	<marge@example.com> # Add schema for all flipr objects.
	 users [appschema] 2014-09-04T23:40:15Z	Marge N. OXVera	<marge@example.com> # Creates table to track our users.
	 flips [appschema users] 2014-09-05T00:16:58Z Marge N. OXVera <marge@example.com> # Adds table for storing flips.
	 userflips [appschema users flips] 2014-09-05T00:18:43Z	Marge N. OXVera	<marge@example.com> # Creates the userflips view.
	 @v1.0.0-dev1 2014-09-05T16:04:48Z Marge N. OXVera <marge@example.com> # Tag v1.0.0-dev1.

	 lists [appschema users] 2014-09-05T17:33:43Z Marge N. OXVera <marge@example.com> # Adds table for storing lists.
	 hashtags [appschema flips] 2014-09-05T17:39:53Z 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
	   - appschema ............... ok
	 Deploying changes to flipr_test
	   + appschema ............... ok
	   + 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 2f065a3] 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 |	   3 +++
	  sqitch.plan	      |	   1 +
	  verify/hashtags.sql |	   3 +++
	  5 files changed, 18 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-vertica-intro/

	 appschema 2014-09-04T18:40:34Z	Marge N. OXVera	<marge@example.com> # Add schema for all flipr objects.
	 users [appschema] 2014-09-04T23:40:15Z	Marge N. OXVera	<marge@example.com> # Creates table to track our users.
	 flips [appschema users] 2014-09-05T00:16:58Z Marge N. OXVera <marge@example.com> # Adds table for storing flips.
	 userflips [appschema users flips] 2014-09-05T00:18:43Z	Marge N. OXVera	<marge@example.com> # Creates the userflips view.
	 @v1.0.0-dev1 2014-09-05T16:04:48Z Marge N. OXVera <marge@example.com> # Tag v1.0.0-dev1.

	 lists [appschema users] 2014-09-05T17:33:43Z Marge N. OXVera <marge@example.com> # Adds table for storing lists.
	 hashtags [appschema flips] 2014-09-05T17:39:53Z 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 8a6a73b] Tag the database with	v1.0.0-dev2.
	  1 files changed, 1 insertions(+), 0 deletions(-)
	 > 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
	   + appschema
	   + 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 Product 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	drop and re-create the view
	   with	the "twitter" column 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
	 # Changed but not updated:
	 #   (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're 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. Of course, the original deploy
       script may not be 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	function deploy	scripts	are already idempotent,	thanks
       to the use of the "OR REPLACE" expression. No matter how	many times a
       deployment script is run, the end result	will be	the same instance of
       the function, with no duplicates	or errors.

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

	 @@ -4,8 +4,9 @@

	  BEGIN;

	 @@ -4,6 +4,6 @@
	  -- requires: flips

	  CREATE OR REPLACE VIEW flipr.userflips AS
	 -SELECT f.id, u.nickname, u.fullname, f.body, f.timestamp
	 +SELECT f.id, u.nickname, u.fullname, u.twitter, f.body, f.timestamp
	    FROM flipr.users u
	    JOIN flipr.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 vertica

	 -SELECT id, nickname, fullname, body, timestamp
	 +SELECT id, nickname, fullname, twitter, body,	timestamp
	    FROM flipr.userflips
	   WHERE FALSE;

       Now try a deployment:

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

       So, are the changes deployed?

	 > vsql	-U dbadmin -c '\dv flipr.userflips'
			   List	of View	Fields
	  Schema |   View    |	 Column	   |	 Type	  | Size
	 --------+-----------+-------------+--------------+------
	  flipr	 | userflips | id	   | int	  |    8
	  flipr	 | userflips | nickname	   | varchar(80)  |   80
	  flipr	 | userflips | fullname	   | varchar(256) |  256
	  flipr	 | userflips | twitter	   | varchar(80)  |   80
	  flipr	 | userflips | body	   | varchar(180) |  180
	  flipr	 | userflips | "timestamp" | timestamptz  |    8

       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?

	 > vsql	-U dbadmin -c '\dv flipr.userflips'
			   List	of View	Fields
	  Schema |   View    |	 Column	   |	 Type	  | Size
	 --------+-----------+-------------+--------------+------
	  flipr	 | userflips | id	   | int	  |    8
	  flipr	 | userflips | nickname	   | varchar(80)  |   80
	  flipr	 | userflips | fullname	   | varchar(256) |  256
	  flipr	 | userflips | twitter	   | varchar(80)  |   80
	  flipr	 | userflips | body	   | varchar(180) |  180
	  flipr	 | userflips | "timestamp" | timestamptz  |    8

       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:

	 > git add .
	 > git commit -m 'Add the twitter column to the	userflips view.'
	 [master 95d6dd0] Add the twitter column to the	userflips view.
	  7 files changed, 30 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.

Author
       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 v5.24.1			  2017-07-03	     sqitchtutorial-vertica(3)

Name | Synopsis | Description | Starting a New Project | Our First Change | On Target | Deploy with Dependency | Add Two at Once | Ship It! | Making a Hash of Things | Making a Hash of Things | In Place Changes | More to Come | Author | License

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