postgresql generate sequence with no gap

Question

I must / have to create unique ID for invoices. I have a table id and another column for this unique number. I use serialization isolation level. Using

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Answer 1

You could create a sequence with no cache , then get the next value from the sequence and use that as your counter.

CREATE SEQUENCE invoice_serial_seq START 101 CACHE 1;
SELECT nextval('invoice_serial_seq');

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