Thank you, Is there a way, in the same idea, to make postgresql 'skip' say every 100 numbers when generating a 'next' in bigserial? (or to insure that every number generated is evenly divisible by 100, and then another db would be 99 and so on) In oracle, if I remember right, there was something called a 'Step' for the sequence values. Vlad On Sun, 08 Mar 2009 01:13 -0700, "Scott Marlowe" <scott.marlowe@xxxxxxxxx> wrote: > On Sat, Mar 7, 2009 at 2:03 PM, V S P <toreason@xxxxxxxxxxx> wrote: > > > And wanted to ask what would be the main challenges I am facing with -- > > from the experience of the users on this list. > > > > Especially I am not sure how to for example manage 'overlapping unique > > IDs' data. > > I'm not expert on a lot of what you're doing, but the standard trick > here is to partition your bigserials. > > The max value for the underlying sequence is 9223372036854775807 which > should give you plenty of space to work in. So, When creating your > bigserials, you can then alter the sequence underneath them to use a > different range on each machine. > > smarlowe=# create table a1 (id bigserial, info text); > NOTICE: CREATE TABLE will create implicit sequence "a1_id_seq" for > serial column "a1.id" > smarlowe=# create table a2 (id bigserial, info text); > NOTICE: CREATE TABLE will create implicit sequence "a2_id_seq" for > serial column "a2.id" > smarlowe=# alter sequence a1_id_seq minvalue maxvalue 19999999999 > start 10000000000; > ALTER SEQUENCE > smarlowe=# alter sequence a2_id_seq minvalue 20000000000 maxvalue > 29999999999 start 20000000000; > ALTER SEQUENCE > > Now those two sequences can't run into each other, and if you move a > record from one machine to another it won't bump into what's already > there. Partitioning by 10billion gives you 922337203 possible > partitions, so if you need bigger but fewer partitions there's plenty > of wiggle room to play with. -- V S P toreason@xxxxxxxxxxx -- http://www.fastmail.fm - IMAP accessible web-mail -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
