[hdf-forum] Advice on way to write HDF file for optimal reading.

[Andrew Cunningham]

Hi,
	 I am looking for advice on the optimal way to R/W a HDF file in C/C+ 
+ under the following circumstances.
	Essentially my data is one large array of single precision data of ,  
say , 1 million rows by , say, 3000 columns. Sometimes it can be  
smaller, of course, and may be larger, but that would be a typical  
'large' problem.

	The data is "received" by columns 1,2,3......N. Obviously I cannot  
hold all the data in memory so I write a column 'hyperslab' one at a  
time as I get the data.
	
	The main requirement is I need to efficiently be able to read a  
random selection of rows. So I need to read, say, the data from a 1000  
rows (random indices) into memory. I do not know before hand which  
rows will need to be read. Obviously the implementation is a to  
construct a hyperslab read of those rows - but is that the most  
efficient way?
	
	Any tips before I dive in?

Andrew
	

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