# partially reading vtkMultiBlockDataSet
**URL:** https://discourse.vtk.org/t/partially-reading-vtkmultiblockdataset/9251
**Category:** Support
**Created:** [August 30, 2022, 10:45am UTC](https://discourse.vtk.org/t/partially-reading-vtkmultiblockdataset/9251 "2022-08-30T10:45:09Z")
**Posts on this page:** 5
**Page:** 1
### Author:  [@philippeseil](https://discourse.vtk.org/u/philippeseil)
#### Post date: [August 30, 2022, 10:45am UTC](https://discourse.vtk.org/t/partially-reading-vtkmultiblockdataset/9251/1 "2022-08-30T10:45:10Z")
Hi all,
I am working on an application where I have to read many (potentially large) vtkMultiBlockDataSet, but only use parts of the data stored in those data sets. Thus, I am looking for a way to only selectively load data in order to minimize disk IO. I could of course parse the .vtm manually to get the paths to the blocks I need, but this is quite cumbersome and hard to maintain. I wonder if there is a way to do this natively in vtk - like telling the reader to parse the .vtm and then obtain a multiblock with only selected blocks, without touching the unneeded data.
Thanks for any help!
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### Author:  [@sridhar-mani](https://discourse.vtk.org/u/sridhar-mani)
#### Post date: [March 26, 2025, 9:17am UTC](https://discourse.vtk.org/t/partially-reading-vtkmultiblockdataset/9251/2 "2025-03-26T09:17:19Z")
any updates on this?
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### Author:  [@lgivord](https://discourse.vtk.org/u/lgivord)
#### Post date: [March 26, 2025, 2:42pm UTC](https://discourse.vtk.org/t/partially-reading-vtkmultiblockdataset/9251/3 "2025-03-26T14:42:09Z")
AFAIK it depends on the reader itself, for example, the exodus reader allow to do such thing. what is your file format and reader that you want to use ?
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### Author:  [@sridhar-mani](https://discourse.vtk.org/u/sridhar-mani)
#### Post date: [March 27, 2025, 6:47am UTC](https://discourse.vtk.org/t/partially-reading-vtkmultiblockdataset/9251/4 "2025-03-27T06:47:38Z")
im trying to read vtkmultiblockdataset
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### Author:  [@lgivord](https://discourse.vtk.org/u/lgivord)
#### Post date: [March 27, 2025, 7:18am UTC](https://discourse.vtk.org/t/partially-reading-vtkmultiblockdataset/9251/5 "2025-03-27T07:18:23Z")
if your file is a vtm indeed it’s currently not possible with the reader but adding such feature could make sense