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Binary versus Integer ...
Posted by: Alexandre Ostanine
Date: August 22, 2012 08:23PM

I've just discovered ...probably bit too late ...or bit too early
that MySQL can work with bit fields ..
directly setted up a test table... works ..OK..

than i added binary (64bit) field to my working table with 1.9mil records...
that previously had 1 integer field with a flag to indicate state of the field ...0,1

ok ..then i did this: (to check state of new system that was bit based ..not field based):

select x from table y where state & 1<<16

I was killed by result ... it was 100 times slower than if i would check the integral field ...WHY ?

it took 0.003sec to check 1.9mil records for a single field ...
and it took 0.5sec if it was bit field ...


JAE @above_equal
JNZ @not_zero..

(and there are 64bit mmx registers, and 128 xmmx registers if needed
so - i guess working on each byte is not an issue here ...)

are taking less than 1 CPU cicle ...(even as on 486)...
Why is this operation takes 100 times more time ?
or you shifting the bit for each iteration ? even if its given as constant ?
even then - it just can not take 100 times more time...

Could you please explain this ?

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Binary versus Integer ...
August 22, 2012 08:23PM

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