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andretti1977

I have a tangentially related question since I don’t use an Olap db: is deleting data so hard to perform? Is it necessarily an immutable storage?

If so, is it a gdpr compliant storage solution? I am asking it since gdpr compliance may require data deletion (or at least anonimization)

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Columnar Db’s want stuff to be contiguous on disk, and deletes cause the rest of the data in that “block” to be rewritten (imagine deleting a chunk out of the middle of an excel table: you’ve got to move everything else up).

This in turn, creates read+write load. Modern OLAP db’s often support it, often via mitigating strategies to minimise the amount of extra work they incur: mark tainted rows, exclude them from queries, and clean up asynchronously; etc.

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