Rails - Apr 2010 - Will rake db:migrate:down VERSION=XXX completely remove that migration from Rails?

What exactly does rake db:migrate:down VERSION=XXX do?  I understand
that it runs the "down" migration, completely removing any columns/
tables that migration may have created, but does this mean that I can
can delete these migration files as well?  I''d like for Rails to have
no knowledge of their existence.  (I was allowing user profile pics
with Paperclip, but have since decided to just use their Gravatars.)

I know you can delete a migration, and even delete those columns from
the schema, but Rails still "remembers" these changes and just updates
them the next time you rake db:migrate.  So, I''d like to completely
rid my app of a particular migration, is rake db:migrate:down then
deleting that migration from the migrate folder the way to do it?

-- 
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en.

You''ll also need to remove that migration''s entry from the
''schema_migrations'' table.  That''s how Rails keeps up
with what
migrations exist, and whether it''s done them all.

On Tue, Apr 6, 2010 at 10:10 PM, GoodGets
<goodgets-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
> What exactly does rake db:migrate:down VERSION=XXX do?  I understand
> that it runs the "down" migration, completely removing any
columns/
> tables that migration may have created, but does this mean that I can
> can delete these migration files as well?  I''d like for Rails to
have
> no knowledge of their existence.  (I was allowing user profile pics
> with Paperclip, but have since decided to just use their Gravatars.)
>
> I know you can delete a migration, and even delete those columns from
> the schema, but Rails still "remembers" these changes and just
updates
> them the next time you rake db:migrate.  So, I''d like to
completely
> rid my app of a particular migration, is rake db:migrate:down then
> deleting that migration from the migrate folder the way to do it?
>
> --
> You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
> To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
> To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe@googlegroups.com.
> For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en.
>
>
-- 
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe@googlegroups.com.
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en.

Thanks Ryan

and, I hope this isn''t too stupid of a question, but where is this
''schema_migrations'' table?

On Apr 6, 11:29 pm, Ryan Waldron
<r...-L2nCScK6t0HQT0dZR+AlfA@public.gmane.org>
wrote:
> You''ll also need to remove that migration''s entry from
the
> ''schema_migrations'' table.  That''s how Rails
keeps up with what
> migrations exist, and whether it''s done them all.
>
>
>
> On Tue, Apr 6, 2010 at 10:10 PM, GoodGets
<goodg...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> > What exactly does rake db:migrate:down VERSION=XXX do?  I understand
> > that it runs the "down" migration, completely removing any
columns/
> > tables that migration may have created, but does this mean that I can
> > can delete these migration files as well?  I''d like for Rails
to have
> > no knowledge of their existence.  (I was allowing user profile pics
> > with Paperclip, but have since decided to just use their Gravatars.)
>
> > I know you can delete a migration, and even delete those columns from
> > the schema, but Rails still "remembers" these changes and
just updates
> > them the next time you rake db:migrate.  So, I''d like to
completely
> > rid my app of a particular migration, is rake db:migrate:down then
> > deleting that migration from the migrate folder the way to do it?
>
> > --
> > You received this message because you are subscribed to the Google
Groups "Ruby on Rails: Talk" group.
> > To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
> > To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
> > For more options, visit this group
athttp://groups.google.com/group/rubyonrails-talk?hl=en.
-- 
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe@googlegroups.com.
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en.

It is in whatever database your app is using.  Rails creates and
maintains it for you.  So if your production database is
''foo_prod'',
there would be a ''schema_migrations'' table there, as well as
in your
''foo_dev'' development database.

I don''t know of a simple way to remove that row without firing up your
database itself (MySQL or whatever).

On Tue, Apr 6, 2010 at 10:43 PM, GoodGets
<goodgets-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
> Thanks Ryan
>
> and, I hope this isn''t too stupid of a question, but where is this
> ''schema_migrations'' table?
>
> On Apr 6, 11:29 pm, Ryan Waldron
<r...-L2nCScK6t0HQT0dZR+AlfA@public.gmane.org> wrote:
>> You''ll also need to remove that migration''s entry
from the
>> ''schema_migrations'' table.  That''s how Rails
keeps up with what
>> migrations exist, and whether it''s done them all.
>>
>>
>>
>> On Tue, Apr 6, 2010 at 10:10 PM, GoodGets
<goodg...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>> > What exactly does rake db:migrate:down VERSION=XXX do?  I
understand
>> > that it runs the "down" migration, completely removing
any columns/
>> > tables that migration may have created, but does this mean that I
can
>> > can delete these migration files as well?  I''d like for
Rails to have
>> > no knowledge of their existence.  (I was allowing user profile
pics
>> > with Paperclip, but have since decided to just use their
Gravatars.)
>>
>> > I know you can delete a migration, and even delete those columns
from
>> > the schema, but Rails still "remembers" these changes
and just updates
>> > them the next time you rake db:migrate.  So, I''d like to
completely
>> > rid my app of a particular migration, is rake db:migrate:down then
>> > deleting that migration from the migrate folder the way to do it?
>>
>> > --
>> > You received this message because you are subscribed to the Google
Groups "Ruby on Rails: Talk" group.
>> > To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org.
>> > To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
>> > For more options, visit this group
athttp://groups.google.com/group/rubyonrails-talk?hl=en.
>
> --
> You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
> To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
> To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe@googlegroups.com.
> For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en.
>
>
-- 
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe@googlegroups.com.
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en.

On Tue, Apr 6, 2010 at 11:29 PM, Ryan Waldron
<rew-L2nCScK6t0HQT0dZR+AlfA@public.gmane.org>
wrote:
> You''ll also need to remove that migration''s entry from
the
> ''schema_migrations'' table.  That''s how Rails
keeps up with what
> migrations exist, and whether it''s done them all.
Running rake db:migrate:down VERSION=XXX should remove the entry.

Otherwise rake db:migrate wouldn''t run the migration again.  A normal
use case for migrate down is:

rake db:migrate

#oops something was wrong in migration 123456
rake db:migrate:down VERSION=123456
edit db/migrate/123456_whatever_it_does
rake db:migrate

> On Tue, Apr 6, 2010 at 10:10 PM, GoodGets
<goodgets-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>> What exactly does rake db:migrate:down VERSION=XXX do?  I understand
>> that it runs the "down" migration, completely removing any
columns/
>> tables that migration may have created,
Well it does whatever YOU told it to in the down part of the
migration. It''s up to you (or whatever you use to edit/generate the
migration) to write the correct code there.

I tend to use Textmate snippets from the rails bundle to do
migrations, and the table/column migration snippets will generate
''undo'' code in the down migration when you expand them in the
up
migration.  But YMMV depending on what tools you use.
>> but does this mean that I can
>> can delete these migration files as well?  I''d like for Rails
to have
>> no knowledge of their existence.  (I was allowing user profile pics
>> with Paperclip, but have since decided to just use their Gravatars.)
>> I know you can delete a migration, and even delete those columns from
>> the schema, but Rails still "remembers" these changes and
just updates
>> them the next time you rake db:migrate.  So, I''d like to
completely
>> rid my app of a particular migration, is rake db:migrate:down then
>> deleting that migration from the migrate folder the way to do it?
When you do rake db:migration  the rake task looks for migrations
under db/migrate which don''t have entries in the schema_migrations
table, and runs those (actually I think it''s a bit more subtle than
that, there''s been discussion of a ''bug'' which can
make the task
ignore migrations with a timestamp older than the newest one in
schema_migrations, which can keep migrations merged from another
branch NOT to be run.  But...

If you run

rake db:migrate:down  version=XXX

and then remove the file db/migrate/XXX_whatever from your source, the
rake task won''t see it and it will be gone.


-- 
Rick DeNatale

Blog: http://talklikeaduck.denhaven2.com/
Github: http://github.com/rubyredrick
Twitter: @RickDeNatale
WWR: http://www.workingwithrails.com/person/9021-rick-denatale
LinkedIn: http://www.linkedin.com/in/rickdenatale

-- 
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe@googlegroups.com.
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en.

So as long as I rake db:migrate:down and delete the migration file
from my local machine, the production database on the server when it
does go live (I haven''t launched the app yet) will have no knowledge
of this migration having ever existed, right?

because that''s all I really care about, and I believe this is true, at
least from from my understanding now

Thank you again Ryan


On Apr 6, 11:53 pm, Ryan Waldron
<r...-L2nCScK6t0HQT0dZR+AlfA@public.gmane.org>
wrote:
> It is in whatever database your app is using.  Rails creates and
> maintains it for you.  So if your production database is
''foo_prod'',
> there would be a ''schema_migrations'' table there, as well
as in your
> ''foo_dev'' development database.
>
> I don''t know of a simple way to remove that row without firing up
your
> database itself (MySQL or whatever).
>
>
>
> On Tue, Apr 6, 2010 at 10:43 PM, GoodGets
<goodg...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> > Thanks Ryan
>
> > and, I hope this isn''t too stupid of a question, but where is
this
> > ''schema_migrations'' table?
>
> > On Apr 6, 11:29 pm, Ryan Waldron
<r...-L2nCScK6t0HQT0dZR+AlfA@public.gmane.org> wrote:
> >> You''ll also need to remove that migration''s
entry from the
> >> ''schema_migrations'' table.  That''s how
Rails keeps up with what
> >> migrations exist, and whether it''s done them all.
>
> >> On Tue, Apr 6, 2010 at 10:10 PM, GoodGets
<goodg...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> >> > What exactly does rake db:migrate:down VERSION=XXX do?  I
understand
> >> > that it runs the "down" migration, completely
removing any columns/
> >> > tables that migration may have created, but does this mean
that I can
> >> > can delete these migration files as well?  I''d like
for Rails to have
> >> > no knowledge of their existence.  (I was allowing user
profile pics
> >> > with Paperclip, but have since decided to just use their
Gravatars.)
>
> >> > I know you can delete a migration, and even delete those
columns from
> >> > the schema, but Rails still "remembers" these
changes and just updates
> >> > them the next time you rake db:migrate.  So, I''d
like to completely
> >> > rid my app of a particular migration, is rake db:migrate:down
then
> >> > deleting that migration from the migrate folder the way to do
it?
>
> >> > --
> >> > You received this message because you are subscribed to the
Google Groups "Ruby on Rails: Talk" group.
> >> > To post to this group, send email to
rubyonrails-talk@googlegroups.com.
> >> > To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
> >> > For more options, visit this group
athttp://groups.google.com/group/rubyonrails-talk?hl=en.
>
> > --
> > You received this message because you are subscribed to the Google
Groups "Ruby on Rails: Talk" group.
> > To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
> > To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
> > For more options, visit this group
athttp://groups.google.com/group/rubyonrails-talk?hl=en.
-- 
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe@googlegroups.com.
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en.

Wow.
Thank you Rick.  Very nice explanation.
Yeah, I dropped the columns by raking ''down'' and have also
deleted
that migration, so I think I''m good to go now.  Also, I don''t
use
textmate, but yeah, I made sure that the "down" migration removed all
the columns the "up" created.

Thank you again Mr. Rick


On Apr 7, 10:36 am, Rick DeNatale
<rick.denat...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
> On Tue, Apr 6, 2010 at 11:29 PM, Ryan Waldron
<r...-L2nCScK6t0HQT0dZR+AlfA@public.gmane.org> wrote:
> > You''ll also need to remove that migration''s entry
from the
> > ''schema_migrations'' table.  That''s how
Rails keeps up with what
> > migrations exist, and whether it''s done them all.
>
> Running rake db:migrate:down VERSION=XXX should remove the entry.
>
> Otherwise rake db:migrate wouldn''t run the migration again.  A
normal
> use case for migrate down is:
>
> rake db:migrate
>
> #oops something was wrong in migration 123456
> rake db:migrate:down VERSION=123456
> edit db/migrate/123456_whatever_it_does
> rake db:migrate
>
> > On Tue, Apr 6, 2010 at 10:10 PM, GoodGets
<goodg...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> >> What exactly does rake db:migrate:down VERSION=XXX do?  I
understand
> >> that it runs the "down" migration, completely removing
any columns/
> >> tables that migration may have created,
>
> Well it does whatever YOU told it to in the down part of the
> migration. It''s up to you (or whatever you use to edit/generate
the
> migration) to write the correct code there.
>
> I tend to use Textmate snippets from the rails bundle to do
> migrations, and the table/column migration snippets will generate
> ''undo'' code in the down migration when you expand them in
the up
> migration.  But YMMV depending on what tools you use.
>
> >> but does this mean that I can
> >> can delete these migration files as well?  I''d like for
Rails to have
> >> no knowledge of their existence.  (I was allowing user profile
pics
> >> with Paperclip, but have since decided to just use their
Gravatars.)
> >> I know you can delete a migration, and even delete those columns
from
> >> the schema, but Rails still "remembers" these changes
and just updates
> >> them the next time you rake db:migrate.  So, I''d like to
completely
> >> rid my app of a particular migration, is rake db:migrate:down then
> >> deleting that migration from the migrate folder the way to do it?
>
> When you do rake db:migration  the rake task looks for migrations
> under db/migrate which don''t have entries in the schema_migrations
> table, and runs those (actually I think it''s a bit more subtle
than
> that, there''s been discussion of a ''bug'' which
can make the task
> ignore migrations with a timestamp older than the newest one in
> schema_migrations, which can keep migrations merged from another
> branch NOT to be run.  But...
>
> If you run
>
> rake db:migrate:down  version=XXX
>
> and then remove the file db/migrate/XXX_whatever from your source, the
> rake task won''t see it and it will be gone.
>
> --
> Rick DeNatale
>
> Blog:http://talklikeaduck.denhaven2.com/
> Github:http://github.com/rubyredrick
> Twitter: @RickDeNatale
> WWR:http://www.workingwithrails.com/person/9021-rick-denatale
> LinkedIn:http://www.linkedin.com/in/rickdenatale
-- 
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe@googlegroups.com.
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en.

On Wed, Apr 7, 2010 at 1:10 PM, GoodGets
<goodgets-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
> So as long as I rake db:migrate:down and delete the migration file
> from my local machine, the production database on the server when it
> does go live (I haven''t launched the app yet) will have no
knowledge
> of this migration having ever existed, right?
>
> because that''s all I really care about, and I believe this is
true, at
> least from from my understanding now
>
> Thank you again Ryan
HA!  My only contribution here was to miss the explanation badly
enough to motivate Rick to write a longer and actually correct one. :)

> On Apr 6, 11:53 pm, Ryan Waldron
<r...-L2nCScK6t0HQT0dZR+AlfA@public.gmane.org> wrote:
>> It is in whatever database your app is using.  Rails creates and
>> maintains it for you.  So if your production database is
''foo_prod'',
>> there would be a ''schema_migrations'' table there, as
well as in your
>> ''foo_dev'' development database.
>>
>> I don''t know of a simple way to remove that row without firing
up your
>> database itself (MySQL or whatever).
>>
>>
>>
>> On Tue, Apr 6, 2010 at 10:43 PM, GoodGets
<goodg...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>> > Thanks Ryan
>>
>> > and, I hope this isn''t too stupid of a question, but
where is this
>> > ''schema_migrations'' table?
>>
>> > On Apr 6, 11:29 pm, Ryan Waldron
<r...-L2nCScK6t0HQT0dZR+AlfA@public.gmane.org> wrote:
>> >> You''ll also need to remove that migration''s
entry from the
>> >> ''schema_migrations'' table.  That''s
how Rails keeps up with what
>> >> migrations exist, and whether it''s done them all.
>>
>> >> On Tue, Apr 6, 2010 at 10:10 PM, GoodGets
<goodg...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>> >> > What exactly does rake db:migrate:down VERSION=XXX do?  I
understand
>> >> > that it runs the "down" migration, completely
removing any columns/
>> >> > tables that migration may have created, but does this
mean that I can
>> >> > can delete these migration files as well?  I''d
like for Rails to have
>> >> > no knowledge of their existence.  (I was allowing user
profile pics
>> >> > with Paperclip, but have since decided to just use their
Gravatars.)
>>
>> >> > I know you can delete a migration, and even delete those
columns from
>> >> > the schema, but Rails still "remembers" these
changes and just updates
>> >> > them the next time you rake db:migrate.  So, I''d
like to completely
>> >> > rid my app of a particular migration, is rake
db:migrate:down then
>> >> > deleting that migration from the migrate folder the way
to do it?
>>
>> >> > --
>> >> > You received this message because you are subscribed to
the Google Groups "Ruby on Rails: Talk" group.
>> >> > To post to this group, send email to
rubyonrails-talk@googlegroups.com.
>> >> > To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
>> >> > For more options, visit this group
athttp://groups.google.com/group/rubyonrails-talk?hl=en.
>>
>> > --
>> > You received this message because you are subscribed to the Google
Groups "Ruby on Rails: Talk" group.
>> > To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org.
>> > To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
>> > For more options, visit this group
athttp://groups.google.com/group/rubyonrails-talk?hl=en.
>
> --
> You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
> To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
> To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe@googlegroups.com.
> For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en.
>
>
-- 
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe@googlegroups.com.
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en.