On Sat, Feb 21, 2015 at 5:33 AM, Arjen Nienhuis <a.g.nienhuis@xxxxxxxxx> wrote: > Hi, > > On 19 Feb 2015 17:12, "brian" <brian@xxxxxxxxxxxxxxxx> 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. >> > > Postgres can use almost anything as a key so it probably depends on the > library you use to access the database. > > If it supports "composite primary keys" you can use the 6 ints as a key: > > PRIMARY KEY (n1, n2, n3, n4, n5, n6) > > The numeric type can hold 192-bit numbers. I think Lazarus supports this as > well. > > You could also use a surrogate key and define a UNIQUE constraint on the 6 > ints or the 192-bit number. You could also use 3 64 bit bigints if that's easier. The other way to do it is bytea. merlin -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
