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## Problem PR #6500 has removed the limiting by number of versions/deletions for time travel calls. We never get informed about how many versions there are, and thus the call would just hang without any indication of progress. ## Summary of changes We improve the pageserver's behaviour with large prefixes, i.e. those with many keys, removed or currently still available. * Add a hard limit of 100k versions/deletions. For the reasoning see https://github.com/neondatabase/cloud/issues/8233#issuecomment-1915021625 , but TLDR it will roughly support tenants of 2 TiB size, of course depending on general write activity and duration of the s3 retention window. The goal is to have a limit at all so that the process doesn't accumulate increasing numbers of versions until an eventual crash. * Lower the RAM footprint for the `VerOrDelete` datastructure. This means we now don't cache a lot of redundant metadata in RAM like the owner ID. The top level datastructure's footprint goes down from 264 bytes to 80 (but it contains strings that are not counted in there). Follow-up of #6500, part of https://github.com/neondatabase/cloud/issues/8233 --------- Co-authored-by: Joonas Koivunen <joonas@neon.tech>