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## Problem See https://neondb.slack.com/archives/C03QLRH7PPD/p1745003314183649 Vacuum doesn't use prefetch because this strange logic in `lazy_scan_heap`: ``` /* And only up to the next unskippable block */ if (next_prefetch_block + prefetch_budget > vacrel->next_unskippable_block) prefetch_budget = vacrel->next_unskippable_block - next_prefetch_block; ``` ## Summary of changes Disable prefetch only if vacuum jumps to next skippable block (there is SKIP_PAGES_THRESHOLD) which cancel seqscan and perform jump only if gap is large enough). Postgres PRs: https://github.com/neondatabase/postgres/pull/620 https://github.com/neondatabase/postgres/pull/621 https://github.com/neondatabase/postgres/pull/622 https://github.com/neondatabase/postgres/pull/623 --------- Co-authored-by: Konstantin Knizhnik <knizhnik@neon.tech>