PostgreSQL bitwise shift operator for 64-bit numbers

Question

I have an issue with bitwise shifting. It works for 32 bit, but I need this up to a 64-bit number.

Example:

select
(1 << 1)  as ok_1,
(1 << 2)  as ok_2,
--...
(1 << 30)  as ok_30,
(1 << 31)  as NOT_ok_31

In the last column (NOT_ok_31) instead -2147483648 I expect (10000000000000000000000000000000)₂ = (1 × 2³¹) + ...+(0 × 2¹) + (0 × 2⁰) = 2147483648

Any Idea? Thanks in advance.

Answer 1

32-bit integer (10000000000000000000000000000000)₂ has the sign bit set so it is a negative number. First cast 1 as bigint so that the result will be a 64-bit integer too.

select
(1 << 1)  as ok_1,
(1 << 2)  as ok_2,
(1::bigint << 31) as ok_31,
(1::bigint << 33) as ok_33;

ok_1	ok_2	ok_31	ok_33
2	4	2147483648	8589934592