I've come across lookup tables, Hamming weights and Brain Kernighan's Algo.
Are they used (combined or separately) in bitmap counting?
Where can I find the coding and please explain the flow a count function
(for a bit counting) via coding rather than the high level architectural
diagrams (which I'm aware of).
I've noted using the below expression to count a particular bits (0 or 1
with minor modification). Could anyone explain at the coding level of
postgresql and what algorithms are used?
postgres=> SELECT LENGTH( REPLACE( CAST( B'101000000000000000000010'
AS TEXT ), '0', ''));
Regards,
K.Kanarupan
Undergraduate,k
Dept. of Computer Science & Engineering
University of Moratuwa
Mobile: +94 777 420 179