Details
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Bug
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Status: In Review (View Workflow)
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Major
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Resolution: Unresolved
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10.11, 11.4, 11.8, 12.3
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Related to performance
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Q1/2026 Server Development
Description
Related to MDEV-38289 and a failure of an end_lsn assertion failure that is being added in MDEV-37949 I found out that the check at the start of log_checkpoint_low() is not preventing redundant writes of FILE_CHECKPOINT records. What I am observing is a stream of identical FILE_CHECKPOINT records pointing to the same checkpoint LSN. These durable writes (including fsync(2) or fdatasync(2) or equivalent) should cost some performance.
I was able to reproduce the problem on 10.11 with the following patch, placing the data directory outside /dev/shm:
diff --git a/storage/innobase/buf/buf0buf.cc b/storage/innobase/buf/buf0buf.cc
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index 189a506c3a3..e4edb020a9c 100644
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--- a/storage/innobase/buf/buf0buf.cc
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+++ b/storage/innobase/buf/buf0buf.cc
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@@ -587,6 +587,7 @@ static bool buf_page_check_lsn(bool check_lsn, const byte *read_buf) noexcept
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" is in the future! Current system log sequence number "
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LSN_PF ".",
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space_id, page_no, page_lsn, current_lsn);
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+ ut_a(((current_lsn - 0x3032) & 15) || current_lsn == 0x3032 || current_lsn == 0x3042);
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if (srv_force_recovery)
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return false;
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diff --git a/storage/innobase/buf/buf0flu.cc b/storage/innobase/buf/buf0flu.cc
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index 43682200710..7bb1d5d0bdc 100644
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--- a/storage/innobase/buf/buf0flu.cc
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+++ b/storage/innobase/buf/buf0flu.cc
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@@ -2013,6 +2013,9 @@ static bool log_checkpoint_low(lsn_t oldest_lsn, lsn_t end_lsn) noexcept
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return true;
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}
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+ //ut_a(oldest_lsn != 0x3032);
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+ ut_a(((oldest_lsn - 0x3032) & 15) || oldest_lsn <= 12354);
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+
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ut_ad(!recv_no_log_write);
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ut_ad(oldest_lsn > log_sys.last_checkpoint_lsn);
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/* Repeat the FILE_MODIFY records after the checkpoint, in case some |
while mysql-test/mtr --rr=-h --parallel=auto innodb.log_corruption_recovery{,,,,,}{,,}; do :; done |
Attachments
Issue Links
- relates to
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MDEV-37949 Implement innodb_log_archive
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- Stalled
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- Closed
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