dhis2-devs team mailing list archive

[Jason Pickering <jason.p.pickering@xxxxxxxxx>]

>
> 2) I noticed this in the help section: "Due to the limitation in number of
> columns per table in the database there is a limit to how many data
> elements that can be selected per data mart export. In postgres this limot
> is 255 (need to verify this number) data elements."
> - Is that the case? (Checked the dhis.uio.no/demo server, which had
> several with more than 250).
> - If so, can you have 250 data element AND 250 indicators, or is it the
> sum that counts?
>
>
It is the sum which counts, and it depends on the column types and can be
increased by increasing the block size of postgres and doing a manual
recompile
This really depends on the actual number  of cross-tab columns, which may
be a product of data elements and periods for instance, or other cross-tab
dimesions.


 You may be able to get away with a larger number than 255, but likely not
more than 1600 (the upper limit provided by the postgres devs) for a
standard install. This could be increased through either a custom
recompile, or more easily (and certainly more robust from a performance
perspective) through table partitioning. However, this would require a lot
of custom stuff to achieve I think, and would probably not be worth the
effort. I would try and experiment and establish an upper limit. If this is
still not acceptable, then you might want to try an custom build of
postgres. I would assume there is also some sort of limit with hibernate
but an not totally sure what this might be.

Regards,
Jason