# ERA5 netcdf encoding since the new CDSAPI release

**URL:** <https://forum.ecmwf.int/t/era5-netcdf-encoding-since-the-new-cdsapi-release/8146>\
**Category:** Feedback and requirements\
**Tags:** api, cds, era5\
**Created:** [2 December 2024 06:11 UTC](https://forum.ecmwf.int/t/era5-netcdf-encoding-since-the-new-cdsapi-release/8146 "2024-12-02T06:11:03Z")\
**Posts on this page:** 1\
**Showing post:** 3

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**Author:** ![Theo\_Mathurin](https://forum.ecmwf.int/user_avatar/forum.ecmwf.int/theo_mathurin/32/1228_2.png) [@Theo\_Mathurin](https://forum.ecmwf.int/u/Theo_Mathurin)\
**Post date:** [6 May 2025 15:24 UTC](https://forum.ecmwf.int/t/era5-netcdf-encoding-since-the-new-cdsapi-release/8146/3 "2025-05-06T15:24:25Z")

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Another issue is the poor reading performance that results from the chunk sizes chosen.

I point to these two posts raising this issue: [Specifying the chunk size for netCDF files](https://forum.ecmwf.int/t/specifying-the-chunk-size-for-netcdf-files/8305) and [Huge performance drop when reading new ERA5 netcdf4 format](https://forum.ecmwf.int/t/huge-performance-drop-when-reading-new-era5-netcdf4-format/12831)

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