Re: Collation and Case Insensitivity

On Thu, Jan 13, 2011 at 02:33:46PM -0000, Phillip Smith wrote:
> Hi,
>
> Im moving over from MS SQL. I've been googling this for ages now and suprisingly cannot find a clear answer.
>
> I want my data in tables to be case insensitive.
>
> This is so i can:
>
> 1. Put keys on natural key fields, for instance a product part number. I product number 'ABC123' inserted i need to disallow 'abc123' to be inserted as a second row. Please don't tell me i have to add another column holding a lowered version of the product number. My database is littered with this need and i would end up bloating my table schema.
>
> 2. I need to query case insensitively. SELECT * FROM product WHERE product_number = 'ABC123' should return the same row as SELECT * FROM product WHERE product_number = 'abc123'
>
> Is there a database wide collation setting i can make. There are lots of online posts regarding using LOWER function for querying. This is a workaround for point (2) but does not remedy point (1) above.
>
> Many thanks
>
> Phillip
>
> Phillip Smith

There is a citext module that may help:

http://www.postgresql.org/docs/9.0/static/citext.html

Alternatively, you could use a trigger on INSERT/UPDATE to
automatically lower() the incoming data which would allow
(2) to work.

Regards,
Ken