The following bug has been logged online:
Bug reference: 2290
Logged by: Oleg Mamontov
Email address: oleg@mamontov.net
PostgreSQL version: 8.0.x/8.1.x
Operating system: FreeBSD 4.x,5.x,6.x
Description: Incorrect sequence increment after backup/restore
Details:
If after CREATE TABLE with SERIAL column i'll change sequence increment to 2
or some other value (with ALTER SEQUENCE) then always work correctly (all
inserted rows will have values incremented by 2).
But after database backup/restore (with pg_dump) this ALTER will not
restored and all next inserted rows will have values incremented by 1
(default for SERIAL data type).
It's seems like a bug...
Changing increment value often used with replication (master database
inserts has odd values and slave database inserts has even) and other
situations.
Sorry for my poor English.