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Single precision cube vs double precision: how to anticipate the effects ?

Question asked by ecausse on Apr 9, 2018
Latest reply on Apr 10, 2018 by ecausse

Hi everyone,

I'm currently reviewing several possibilities to optimize the size of our cubes. By default, everything was created as double precision cubes, but this might not be necessary.
After some testing, I found that the gap between single and double precision cubes is not always significant, however I find it difficult to anticipate the effect of the rounding.

In the official documentation, it is only written:

Floating-point numeric type (4 Bytes). Each cell occupies 4 bytes.

Numbers that need more than 4 bytes to be saved will berounded.


Can we have something more specific ? When I compare the input and output of the data reader, I cannot find a precise logic for the rounding. I suppose this is linked to a binary format rounding but any explanation is welcome