Waiting for 9.2 – NOT VALID CHECKS

On 30th of June, Alvaro Herrera committed patch:

Enable CHECK constraints to be declared NOT VALID
This means that they can initially be added to a large existing table
without checking its initial contents, but new tuples must comply to
them; a separate pass invoked by ALTER TABLE / VALIDATE can verify
existing data and ensure it complies with the constraint, at which point
it is marked validated and becomes a normal part of the table ecosystem.
An non-validated CHECK constraint is ignored in the planner for
constraint_exclusion purposes; when validated, cached plans are
recomputed so that partitioning starts working right away.
This patch also enables domains to have unvalidated CHECK constraints
attached to them as well by way of ALTER DOMAIN / ADD CONSTRAINT / NOT
VALID, which can later be validated with ALTER DOMAIN / VALIDATE
Thanks to Thom Brown, Dean Rasheed and Jaime Casanova for the various
reviews, and Robert Hass for documentation wording improvement
This patch was sponsored by Enova Financial.

Continue reading Waiting for 9.2 – NOT VALID CHECKS

getting multiple values from sequences

there are this situations where you need (or you think you need) to get multiple values from sequence.

for example – you're importing lots of data: some objects, some objects which relate to base objects, and so on.

of course you can do it all with simple inserts, and currval, but it would be rather slow:

Continue reading getting multiple values from sequences