# selecting a subset without opening the entire file

**URL:** <https://forum.hdfgroup.org/t/selecting-a-subset-without-opening-the-entire-file/2988>\
**Category:** Hdf-forum archives\
**Created:** [August 30, 2013, 5:25pm UTC](https://forum.hdfgroup.org/t/selecting-a-subset-without-opening-the-entire-file/2988 "2013-08-30T17:25:39Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Marcio\_Alexandre\_Bar](https://forum.hdfgroup.org/letter_avatar_proxy/v4/letter/m/7ba0ec/32.png) [@Marcio\_Alexandre\_Bar](https://forum.hdfgroup.org/u/Marcio_Alexandre_Bar)\
**Post date:** [August 30, 2013, 5:25pm UTC](https://forum.hdfgroup.org/t/selecting-a-subset-without-opening-the-entire-file/2988/1 "2013-08-30T17:25:39Z")

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I am using the example at  
[http://www.hdfgroup.org/hdf-java-html/hdf-object/javaExample/H5SubsetSelect.java](http://www.hdfgroup.org/hdf-java-html/hdf-object/javaExample/H5SubsetSelect.java).  
But as far as I know, the call to testFile.open reads the entire file  
structure into memory. I have a very large file and I only want to  
select a subset of a dataset inside that file. Is there a way that I  
can read the subset without opening the entire file?

Thank you,

Marcio