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I haven't read that paper (Learned Index Structures), but things like gperf have existed for decades. Are these enhanced data structures dynamic, i.e. unlike gperf which is a static one, does it reoptimize as you insert new elements?

In the case of the hash table, I assume it's using the model to compute the hash function.

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No, it doesn't handle inserts. On the other hand, the paper writes:

"An ... approach to handling inserts is to build a delta-index. All inserts are kept in buffer and from time to time merged with a potential retraining of the model."

Under some assumptions it does handle inserts. From [1]: Finally, assume that the inserts follow roughly a similar pattern as the learned CDF; [...] Under these assumptions the model might not need to be retrained at all.

[1] https://www.arxiv-vanity.com/papers/1712.01208v1/

This is not like gperf.

I think it is a bit like gperf. What do you consider the big difference?

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