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
Description
I encountered this anomaly while adjusting the test mariabackup.unsupported_redo for MDEV-41152. I ended up implementing the following:
diff --git a/mysql-test/suite/mariabackup/unsupported_redo.test b/mysql-test/suite/mariabackup/unsupported_redo.test
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index deb5b768802..cbfbcc43766 100644
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--- a/mysql-test/suite/mariabackup/unsupported_redo.test
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+++ b/mysql-test/suite/mariabackup/unsupported_redo.test
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@@ -57,6 +57,9 @@ ALTER TABLE t21 FORCE, ALGORITHM=INPLACE;
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--echo # Create partial backup (excluding table t21), Ignore the
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--echo # unsupported redo log for the table t21.
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+# Discard the FILE_CREATE record for creating t21
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+SET GLOBAL innodb_log_checkpoint_now=ON;
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+
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--disable_result_log
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exec $XTRABACKUP --defaults-file=$MYSQLTEST_VARDIR/my.cnf --backup --parallel=10 "--tables-exclude=test.t21" --target-dir=$targetdir --innodb_log_checkpoint_now=1;
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--enable_result_log |
Note that the exec statement is supposed to execute the statement already, via the mariadb-backup option that had been introduced in MDEV-30000 and whose default value was changed in MDEV-36159.
To my surprise, the t21.ibd would be recovered based on a FILE_CREATE record. It turns out that the request to force a log checkpoint is asynchronous, not synchronous:
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xtrabackup_backup_func() |
if (innodb_log_checkpoint_now) { |
msg("Initiating checkpoint"); |
if (mysql_send_query(mysql_connection, |
C_STRING_WITH_LEN("SET GLOBAL " |
"innodb_log_checkpoint_now=ON;"))) { |
msg("initiating checkpoint failed"); |
return(false); |
}
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}
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// …
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log_sys.create();
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/* get current checkpoint_lsn */ |
{
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log_sys.latch.wr_lock();
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mysql_mutex_lock(&recv_sys.mutex);
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dberr_t err = recv_sys.find_checkpoint();
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// …
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/* try to wait for a log checkpoint, but do not fail if the |
server does not support this */
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if (innodb_log_checkpoint_now != false) { |
mysql_read_query_result(mysql_connection);
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msg("Finished waiting for checkpoint"); |
}
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According to the rr record traces that I created from the mariadbd process and the two mariadb-backup invocations (both for backup and prepare), the checkpoint request was submitted, but not fully executed before recv_sys.find_checkpoint() had determined that the latest checkpoint is the oldest one. We really need synchronous execution:
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xtrabackup_backup_func() |
msg("cd to %s", mysql_real_data_home); |
encryption_plugin_backup_init(mysql_connection);
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if (innodb_log_checkpoint_now) { |
xb_mysql_query(
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mysql_connection,
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"SET GLOBAL innodb_log_checkpoint_now=ON;", |
false, false); |
}
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Attachments
Issue Links
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- Closed
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- In Review
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