Re: popcount

David Fetter wrote:

+Datum
+byteapopcount(PG_FUNCTION_ARGS)
+{
+ bytea *t1 = PG_GETARG_BYTEA_PP(0);
+ int len, result;
+
+ len = VARSIZE_ANY_EXHDR(t1);
+ result = pg_popcount(VARDATA_ANY(t1), len);
+
+ PG_RETURN_INT32(result);
+}

The input may have more than 2 billion bits set to 1. The biggest possible
result should be 8 billion for bytea (1 GB with all bits set to 1).
So shouldn't this function return an int8?

There is a pre-existing function in core: bit_length(bytea) returning int4,
but it errors out for large values (in fact it's a SQL function that returns
octet_length($1)*8).

For the varbit case, it doesn't seem like it can hold so many bits, although
I don't see the limit documented in
https://www.postgresql.org/docs/current/datatype-bit.html

Best regards,
--
Daniel Vérité
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