Postgres %% in function

Question

What does the "%%" in this statement mean?

SELECT nextval(seq_name) %% 1024 INTO seq_id;

And why does Postgres say, when I use it?

operator does not exist: bigint %% integer

Answer 1

Most probably, it's an artifact from translating dynamic SQL with format(), which requires to double % characters. Should be the modulo operator % if translated correctly, which also makes sense for a sharding solution or similar. Effectively, you get numbers cycling from 0 to 1023.

I suspect it's the same as we already dealt with here:

• What does %% in PL/pgSQL mean?