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[netCDF #ZFB-587742]: Reading variable with strides very slow


Vars in netcdf is inherently slow
(when stride > 1) because it cannot
easily make use of bulk read operations.
So the library must read element by element
from the underlying disk storage. This has
a noticeable effect on performance. This is not
easy to fix because it must do the read using only
the memory that is passed to it by the client. 

For netcdf versions before 4.3.0 (including 4.1.3)
there was an additional factor. For historical
reasons, vars was implemented in terms of varm
so there was some additional overhead.

If you upgrade to 4.3.0, you will see some performance
improvement but not, probably, enough to solve your problem.

Sorry I do not have better news.
=Dennis Heimbigner
=Dennis Heimbigner

Ticket Details
Ticket ID: ZFB-587742
Department: Support netCDF
Priority: Normal
Status: Closed

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