Thread: schema change tracking

> On May 16, 2019, at 5:41 PM, Benedict Holland <benedict.m.holland@gmail.com> wrote:
>
> Hi All,
>
> I am fairly this question has many answers but here it goes:
>
> I need a tool that can track schema changes in a postgesql database, write scripts to alter the tables, and store
thosechanges in git. Are there tools that exist that can do this? 

If you're looking for something that'll reverse engineer schema change scripts from a database someone has made ad-hoc
changesto ... try and avoid doing that if at all possible. Use the change scripts in git as the source of truth. 

If you do that there are many answers, starting at "it's fairly easy to do yourself, with a simple schema version and
upgrade/ downgrade scripts". Depending on what language you're writing your app in there may be libraries that can
help.

But if you're looking for something standalone, look at https://sqitch.org

Cheers,
  Steve

On 5/16/19 9:41 AM, Benedict Holland wrote:
> I need a tool that can track schema changes in a postgesql database, 
> write scripts to alter the tables, and store those changes in git. Are 
> there tools that exist that can do this?
> 
> BTW, I know if I use a framework with some form of model tracking 
> (laravel and Django), those can do it. The application I am writing does 
> not track model files and I really cannot compare sql schema dumps 
> across versions. It would be far too time-consuming.

For Python database migrations when I'm not using Django or SQLAlchemy 
I've enjoyed yoyo migrations:

https://ollycope.com/software/yoyo/latest/

If you are using SQLAlchemy then I'd go with Alembic:

https://pypi.org/project/alembic/

Btw I don't *think* this is what you're looking for, but on the Postgres 
side you can also set `log_statement='ddl'` to audit the changes:

https://blog.hagander.net/why-are-you-not-logging-your-ddl-142/

Or for something more elaborate you could use Event Triggers. The docs 
have an example you could start from:

https://www.postgresql.org/docs/current/event-trigger-example.html

-- 
Paul              ~{:-)
pj@illuminatedcomputing.com

On 5/16/19 10:55 AM, Benedict Holland wrote:
> Hi All!
> 
> Thanks for the replies. I am looking for a solution, possibly 3rd party, 
> where I write changes to the schema and it keeps track of the changes I 
> made. I am used to doing stuff in pgadmin4 but I don't mind something else.
> 
> This isn't really ad-hoc. This is more like, I have a v1.0 release 
> coming out soon and I have made dozens or hundreds of changes to the 
> schema from the alpha. Right now, I can destroy the databases and 
> recreate them without data loss because it is in active development. 
> When this gets released, we need some way to make sure that we can 
> easily migrate between release versions and that means schema change 
> tracking. Basically, to Steve's concern, I don't have to go back and 
> figure out changes (thankfully, I have done that and it sucks) but we 
> need something from an initial release moving forward.
> 
> I don't have time to write my own and this problem is complex enough to 
> either buy a solution or go with a 3rd party application.
> 
> So far, SQITCH is looking like a winner. Yoyo can work as I have access 
> to python. We are not using SQLAlchemy but I don't see a reason why we 
> can't.

I will second the motion on Sqitch. It has met all my needs and is 
framework agnostic.

> 
> Thanks all for the suggestions. This is great.
> ~Ben
> 

>


-- 
Adrian Klaver
adrian.klaver@aklaver.com