>> > I have table containing different types of documents (type A, B and C).
>> >
>> > Each document type must have separate sequential ID starting at 1
>> >
>> > ID of first inserted record of type A must be set to 1
>> > ID of first inserted record of type B must be also set to 1
>> > ID of second record of type A must be set to 2
>> > etc.
>>
> If you are happy with the fact that a sequence may leave a whole in
> the numbers. You are probably best to no set a default value for an
> integer, or big integer. Then run a before trigger for each row. That
> trigger will assign a value to the column based on the value given for
> the type.
Russell,
thank you.
I'm a new to Postgres.
Is there any sample how to write such trigger ?
Before inserting each row it should set document id from sequence
corresponding to insertable document type.
Andrus.