# Library for investigating database schemas?

**URL:** <https://www.ruby-forum.com/t/library-for-investigating-database-schemas/112478>\
**Category:** Ruby\
**Created:** [August 20, 2007, 12:57am UTC](https://www.ruby-forum.com/t/library-for-investigating-database-schemas/112478 "2007-08-20T00:57:59Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Mario\_TSL](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/df705f/32.png) [@Mario\_TSL](https://www.ruby-forum.com/u/Mario_TSL)\
**Post date:** [August 20, 2007, 12:57am UTC](https://www.ruby-forum.com/t/library-for-investigating-database-schemas/112478/1 "2007-08-20T00:57:59Z")

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I’m wondering what libraries are available for accessing the most  
comprehensive information for a database schema. In particular, I want  
information on:

- columns per table
- foreign keys
- column constraints (uniqueness, etc.)
- indexes

I am not sure if this information is accessible via ActiveRecord (some  
is regarding the columns) or via DBI.

I will be using a MySQL database (and have heard about  
[MySQL/Ruby](http://www.tmtm.org/en/mysql/ruby/)), but I would rather work with a  
generic library providing a standard API that is database agnostic.  
Also, I know I can get to this information by querying the database  
INFORMATION\_SCHEMA directly, but, again, I would rather the library be  
oblivious to the underlying database and simply provide the schema  
information.

Does such a library exist?

Thanks.  
Mario T. Lanza

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**Author:** ![Mario\_TSL](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/df705f/32.png) [@Mario\_TSL](https://www.ruby-forum.com/u/Mario_TSL)\
**Post date:** [August 20, 2007, 3:51am UTC](https://www.ruby-forum.com/t/library-for-investigating-database-schemas/112478/2 "2007-08-20T03:51:28Z")

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I think I’ve uncovered some ways to do this. If there’s a better way,  
please say so:

> - columns per table

pp Person.columns

> - foreign keys

pp Person.reflections (not per the database itself but per ActiveRecord)

> - column constraints (uniqueness, etc.)

??

> - indexes

pp ActiveRecord::Base.connection.indexes(‘people’)

Is there a one-stop library for gathering all this info.? Right now,  
what I’m doing is sort of a mish-mash.

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<div class="post-metadata">

**Author:** ![Mario\_TSL](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/df705f/32.png) [@Mario\_TSL](https://www.ruby-forum.com/u/Mario_TSL)\
**Post date:** [August 23, 2007, 6:45am UTC](https://www.ruby-forum.com/t/library-for-investigating-database-schemas/112478/3 "2007-08-23T06:45:50Z")

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Mario T. Lanza wrote:

> I’m wondering what libraries are available for accessing the most  
> comprehensive information for a database schema.

As you found, ActiveRecord already fetches column names. The extra  
features you’ve asked for are variously implemented in gems, in  
particular composite keys, magic models and DrySQL.

Clifford H…