# Remove columns before training

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**Category:** Beginners\
**Created:** [January 4, 2023, 7:36am UTC](/static-proxy?url=https%3A%2F%2Fdiscuss.huggingface.co%2Ft%2Fremove-columns-before-training%2F28908 "2023-01-04T07:36:50Z")\
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**Author:** ![cravephi](https://avatars.discourse-cdn.com/v4/letter/c/d78d45/32.png) [@cravephi](/static-proxy?url=https%3A%2F%2Fdiscuss.huggingface.co%2Fu%2Fcravephi)%5C
**Post date:** [January 4, 2023, 7:36am UTC](/static-proxy?url=https%3A%2F%2Fdiscuss.huggingface.co%2Ft%2Fremove-columns-before-training%2F28908%2F1 "2023-01-04T07:36:50Z")

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Hi,

I see in many examples that we remove unnecessary columns from the dataset, before training.  
Is it mandatory? I guess Trainer will take the columns produced by the tokenizer anyway (together with the “labels” columns).  
Is it to save some IOs? I guess transformer does not load unnecessary columns, but not sure then, why in examples, we remove them.

Sorry, very beginner question here 🙂