On 02/19/2015 09:10 AM, brian wrote:
> Hi folks,
>
> I have a single-user application which is growing beyond the
> fixed-format data files in which it currently holds its data, I need a
> proper database as the backend. The front end is written using Lazarus
> and FreePascal under Linux, should anyone feel that makes a
> difference. The database will need to grow to around 250,000 records.
>
> My problem is with the data field which is the (unique) key. It's
> really a single 192-bit integer (it holds various bits of bitmapped
> data) which I currently hold as six 32-bit integers, but can convert
> if needed when transferring the data.
>
> How would you advise that I hold this field in a Postgres database,
> given the requirement for the whole thing to be a unique key? The
> first 64 bits change relatively infrequently, the last 128 bits will
> change with virtually every record. The last 128 bits will ALMOST be
> unique in themselves, but not quite. :(
>
> Thanks,
>
> Brian.
>
>
If your application understands/parses/makes use of the data in those
192 bites, I would reload with an additional unique id field. For the
intended number of rows of data a sequence would be fine, though I'm
partial to UUIDs. Alternatively map the 192 bytes to two fields and make
a unique key of both of them. Third alternative would be to use a binary
BitString a suggested by Brian.