Re: Alternative to serial primary key - Mailing list pgsql-sql

Hi, David,

David Clarke wrote:
> On 7/6/06, Markus Schaber <schabi@logix-tt.com> wrote:
>> This is a good idea if you want to have taller indices, but you still
>> need to re-check the "real" key due to hash collisions.
> 
> I am aware there are collisions with md5 but without any actual proof
> I believe the risk to be very low with the data I'm storing which is a
> kind of scrubbed free form residential address.

Then you'll have to use the re-check approach, like:

SELECT * FROM foo WHERE hashed_key = hash(mykey) && plain_key = mykey;

And then have an non-unique index on hashed_key, and probably no index n
my_key (to give the planner a hint which index to use).

HTH,
Markus
-- 
Markus Schaber | Logical Tracking&Tracing International AG
Dipl. Inf.     | Software Development GIS

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