...is really cool, but I don't see how to modify it for the case where the domain of the permutation has a cardinality that is not a power of 2, as it is in my case (cardinality = 900000).
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(In the crypto world there are "format preserving encryption" techniques that probably could do what I want to do, but their focus on cryptographic strength makes learning and implementing them tough going, plus, the performance will probably be poor, since high workloads are an asset for such crypto applications. Since cryptographic strength is not something I need, I'm trying to find non-crypt-grade alternatives.)
Thanks in advance!
kynn
Hi Kynn,
How about (note that 'payload' could be any set of valid columns):
-- using a crude Linear Congruential Generator -- not very random, but does NOT create duplicates
DROP TABLE IF EXISTS rtab; DROP SEQUENCE IF EXISTS rseq;
CREATE SEQUENCE rseq;
CREATE TABLE rtab ( id int PRIMARY KEY default(100000 + (nextval('rseq') * 543537 + 997) % 900000), payload int NOT NULL );
INSERT INTO rtab (payload) VALUES (generate_series(1, 100000));
