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Do not assign max(lsn) to maxLastWrittenLsn in SetLastWrittenLSNForBlockv #563

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Merged
knizhnik merged 2 commits into from
Jan 24, 2025
Merged

Do not assign max(lsn) to maxLastWrittenLsn in SetLastWrittenLSNForBlockv #563

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Do not assign max(lsn) to maxLastWrittenLsn in SetLastWrittenLSNForBl…
knizhnik Jan 22, 2025
46f9b96
Do not assign max(lsn) to maxLastWrittenLsn in SetLastWrittenLSNForBl…
knizhnik Jan 22, 2025
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5 changes: 1 addition & 4 deletions src/backend/access/transam/xlog.c
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Original file line number Diff line number Diff line change
Expand Up @@ -6954,7 +6954,6 @@ SetLastWrittenLSNForBlockv(const XLogRecPtr *lsns, RelFileLocator relfilenode,
for (int i = 0; i < nblocks; i++)
{
XLogRecPtr lsn = lsns[i];
max = Max(max, lsn);

key.blockNum = blockno + i;
entry = hash_search(lastWrittenLsnCache, &key, HASH_ENTER, &found);
Expand Down Expand Up @@ -6983,11 +6982,9 @@ SetLastWrittenLSNForBlockv(const XLogRecPtr *lsns, RelFileLocator relfilenode,
}
/* Link to the end of LRU list */
dlist_push_tail(&XLogCtl->lastWrittenLsnLRU, &entry->lru_node);
max = Max(max, lsn);
}

if (max > XLogCtl->maxLastWrittenLsn)
XLogCtl->maxLastWrittenLsn = max;
Comment on lines -6988 to -6989
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@MMeent MMeent Jan 22, 2025

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if XLogCtl->maxLastWrittenLsn isn't the maximum of all lastWrittenLsns, then what is it?

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@knizhnik knizhnik Jan 22, 2025

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It is maximal last written LSN of pages not present in the cache.
So this value is used for page not found in the LwLSN cache.


LWLockRelease(LastWrittenLsnLock);

return max;
Expand Down