[netCDFJava #CRA-892492]: Using Java NetCDF With a Large HDF5 Database - Performance Questions

I have an experimental version of the netcdf-c library that improves the
metadata read performance. It needs testing. It should appear in the
next release plus 1 (probably called 4.5.2 or 4.6). I will try to
announce on the netcdf mailing list.


> The XML formatted text dump from the NCdumpW call resulted in a file that
> is 14.8 MB in size.  I do not how how that would boil down to the binary
> data in the header to the HDF5 database to know if that is the cause of
> the performance problems.
> 
> -Creighton Donnald
> Johns Hopkins University
> Applied Physics Laboratory
> 
> 
> On 5/26/17, 12:53 PM, "Unidata netCDF Java Support"
> <address@hidden> wrote:
> 
> >Can you at least tell me the size (in characters) of the header (using
> >h5dump
> >or ncdump or NCdumpW)? A very large header can be partly responsible for
> >performance issues. The header is read once per file open. Your report
> >would seem consistent with the cost of reading the header in Java.
> >We rarely encounter really large headers so we have not optimized for
> >that case.
> >
> >I suspect, however, that your original thought was correct. Our
> >Java-native
> >HDF5 implementation is probably the problem. I have put it on our list of
> >issues to look at (see https://github.com/Unidata/thredds/issues/847)
> >but it may take a while.
> >
> >=Dennis Heimbigner
> >  Unidata
> >
> >
> >Ticket Details
> >===================
> >Ticket ID: CRA-892492
> >Department: Support netCDF Java
> >Priority: Normal
> >Status: Closed
> >===================
> >NOTE: All email exchanges with Unidata User Support are recorded in the
> >Unidata inquiry tracking system and then made publicly available through
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> >this way, you must let us know in each email you send to us.
> >
> >
> 
> 

=Dennis Heimbigner
  Unidata


Ticket Details
===================
Ticket ID: CRA-892492
Department: Support netCDF Java
Priority: Critical
Status: Closed
===================
NOTE: All email exchanges with Unidata User Support are recorded in the Unidata 
inquiry tracking system and then made publicly available through the web.  If 
you do not want to have your interactions made available in this way, you must 
let us know in each email you send to us.