Want to retrieve a date type from a postgres table using libpq PQexecParams() in binary mode (please humor me). https://www.postgresql.org/docs/14/datatype-datetime.html says that a date is 4 bytes (4713 BC to 5874897 AD). src/include/utils/date.h defines:
typedef int32 DateADT;
Something like this:
int32_t date_val = be32toh PQgetvalue(res, 0, 17)));
Gives date_val=1,466,004,328 for 2022-10-25.
Since 4713BC is the start of the Julian calendar thought it might be a simple day count but the value is too large (2,459,878 days from 1 Jan 4713BC to 2022-10-25). So clearly not a day count. My simple maths gives me 585.966... ticks per day.
How do I interpret the 4 bytes of postgresql 'date' value?