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## Problem See https://neondb.slack.com/archives/C033A2WE6BZ/p1729007738526309?thread_ts=1722942856.987979&cid=C033A2WE6BZ When replica receives WAL record which target page is not present in shared buffer, we evict this page from LFC. If all pages from the LFC chunk are evicted, then chunk is moved to the beginning of LRU least to force it reuse. Unfortunately access_count is not checked and if the entry is access at this moment then this operation can cause LRU list corruption. ## Summary of changes Check `access_count` in `lfc_evict` ## Checklist before requesting a review - [ ] I have performed a self-review of my code. - [ ] If it is a core feature, I have added thorough tests. - [ ] Do we need to implement analytics? if so did you add the relevant metrics to the dashboard? - [ ] If this PR requires public announcement, mark it with /release-notes label and add several sentences in this section. ## Checklist before merging - [ ] Do not forget to reformat commit message to not include the above checklist Co-authored-by: Konstantin Knizhnik <knizhnik@neon.tech>
neon extension consists of several parts:
shared preload library neon.so
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implements storage manager API and network communications with remote page server.
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walproposer: implements broadcast protocol between postgres and WAL safekeepers.
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control plane connector: Captures updates to roles/databases using ProcessUtility_hook and sends them to the control ProcessUtility_hook.
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remote extension server: Request compute_ctl to download extension files.
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file_cache: Local file cache is used to temporary store relations pages in local file system for better performance.
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relsize_cache: Relation size cache for better neon performance.
SQL functions in neon--*.sql
Utility functions to expose neon specific information to user and metrics collection. This extension is created in all databases in the cluster by default.