pt-table-checksum檢測不出主從差別處理

幾個月前寫過pt-table-checksum 3.0.4檢測不出主從差別數據，當時的解決方案是使用舊版本，另外一個挫方法是自行設置binlog_format='STATEMENT'。如今已經發布到3.0.9版本，結果又遇到相同的坑~
最近幾版pt-table-checksum(已覈實僅3.0.4和3.0.9有問題)在binlog_format='row'，且主從存在差別數據時，卻檢測不出主從差別。緣由就是處理過程當中主上沒有SET @@binlog_format := 'STATEMENT'，致使下面兩個核心語句不是以statement格式記錄，從庫不會進行CRC32相關運算，主從永遠一致~

# pt-table-checksum 3.0.4檢測不出差別數據
[root@ZST2 ~]# /usr/local/bin/pt-table-checksum --nocheck-binlog-format --nocheck-replication-filters --recursion-method=hosts --replicate=replcrash.checksums --databases=replcrash --tables=py_user,py_user_innodb --host=192.168.85.132 --port=3306 --user=mydba --password=mysql5721
            TS ERRORS  DIFFS     ROWS  CHUNKS SKIPPED    TIME TABLE
05-08T09:41:15      0      0        8       1       0   0.257 replcrash.py_user
05-08T09:41:16      0      0    67740       5       0   1.056 replcrash.py_user_innodb

# 兩個核心語句
REPLACE INTO `replcrash`.`checksums` (db, tbl, chunk, chunk_index, lower_boundary, upper_boundary, this_cnt, this_crc) SELECT 'replcrash', 'py_user', '1', NULL, NULL, NULL, COUNT(*) AS cnt, COALESCE(LOWER(CONV(BIT_XOR(CAST(CRC32(CONCAT_WS('#', `uid`, convert(`name` using utf8mb4), `add_time`, convert(`server_id` using utf8mb4), CONCAT(ISNULL(`name`), ISNULL(`add_time`), ISNULL(`server_id`)))) AS UNSIGNED)), 10, 16)), 0) AS crc FROM `replcrash`.`py_user` /*checksum table*/
UPDATE `replcrash`.`checksums` SET chunk_time = '0.004092', master_crc = '5abbd632', master_cnt = '8' WHERE db = 'replcrash' AND tbl = 'py_user' AND chunk = '1'

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經過對比舊版本(2.2.3)的/usr/local/bin/pt-table-checksum代碼，發現只需稍微調整代碼便可正常使用

# pt-table-checksum 3.0.4 只需註釋掉第9335行和9364行，這層邏輯應該應用於任何狀況下，所以不須要使用if判斷
[root@ZST2 ~]# vim /usr/local/bin/pt-table-checksum
...
9335       #if ( $o->get('check-binlog-format') ) {
9336         # https://bugs.launchpad.net/percona-toolkit/+bug/919352
9337         # The tool shouldn't blindly attempt to change binlog_format;
9338         # instead, it should check if it's already set to STATEMENT.
9339         # This is becase starting with MySQL 5.1.29, changing the format
9340         # requires a SUPER user.
9341         if ( VersionParser->new($dbh) >= '5.1.5' ) {
9342            $sql = 'SELECT @@binlog_format';
9343            PTDEBUG && _d($dbh, $sql);
9344            my ($original_binlog_format) = $dbh->selectrow_array($sql);
9345            PTDEBUG && _d('Original binlog_format:', $original_binlog_format);
9346            if ( $original_binlog_format !~ /STATEMENT/i ) {
9347               $sql = q{/*!50108 SET @@binlog_format := 'STATEMENT'*/};
9348               eval {
9349                  PTDEBUG && _d($dbh, $sql);
9350                  $dbh->do($sql);
9351               };
9352               if ( $EVAL_ERROR ) {
9353                  die "Failed to $sql: $EVAL_ERROR\n"
9354                     . "This tool requires binlog_format=STATEMENT, "
9355                     . "but the current binlog_format is set to "
9356                     ."$original_binlog_format and an error occurred while "
9357                     . "attempting to change it.  If running MySQL 5.1.29 or newer, "
9358                     . "setting binlog_format requires the SUPER privilege.  "
9359                     . "You will need to manually set binlog_format to 'STATEMENT' "
9360                     . "before running this tool.\n";
9361               }
9362            }
9363         }
9364       #}
...

# 查看pt版本
[root@ZST2 ~]# /usr/local/bin/pt-table-checksum --version
pt-table-checksum 3.0.4
[root@ZST2 ~]# 
# 修改後檢測出主從不一致
[root@ZST2 ~]# /usr/local/bin/pt-table-checksum --nocheck-binlog-format --nocheck-replication-filters --recursion-method=hosts --replicate=replcrash.checksums --databases=replcrash --tables=py_user,py_user_innodb --host=192.168.85.132 --port=3306 --user=mydba --password=mysql5721
            TS ERRORS  DIFFS     ROWS  CHUNKS SKIPPED    TIME TABLE
05-08T09:51:32      0      1        8       1       0   0.030 replcrash.py_user
05-08T09:51:33      0      0    67740       5       0   0.561 replcrash.py_user_innodb
[root@ZST2 ~]# 

# general-log信息
[root@ZST1 ~]# cat /data/mysql/mysql3306/data/ZST1.log |more
...
2018-05-08T01:51:32.315064Z        30 Query     SHOW VARIABLES LIKE 'version%'
2018-05-08T01:51:32.318337Z        30 Query     SHOW ENGINES
2018-05-08T01:51:32.319229Z        30 Query     SHOW VARIABLES LIKE 'innodb_version'
2018-05-08T01:51:32.322518Z        30 Query     SELECT @@binlog_format
2018-05-08T01:51:32.323019Z        30 Query     /*!50108 SET @@binlog_format := 'STATEMENT'*/
2018-05-08T01:51:32.323453Z        30 Query     SET SESSION TRANSACTION ISOLATION LEVEL REPEATABLE READ
2018-05-08T01:51:32.324012Z        30 Query     SHOW VARIABLES LIKE 'wsrep_on'
2018-05-08T01:51:32.327830Z        30 Query     SELECT @@SERVER_ID
2018-05-08T01:51:32.328416Z        30 Query     SHOW SLAVE HOSTS
2018-05-08T01:51:32.344178Z        30 Query     SHOW VARIABLES LIKE 'wsrep_on'
2018-05-08T01:51:32.347571Z        30 Query     SELECT @@SERVER_ID
2018-05-08T01:51:32.351692Z        30 Query     SHOW VARIABLES LIKE 'wsrep_on'
2018-05-08T01:51:32.355034Z        30 Query     SELECT @@SERVER_ID
2018-05-08T01:51:32.359543Z        30 Query     SHOW DATABASES LIKE 'replcrash'
2018-05-08T01:51:32.360406Z        30 Query     CREATE DATABASE IF NOT EXISTS `replcrash` /* pt-table-checksum */
2018-05-08T01:51:32.361538Z        30 Query     USE `replcrash`
2018-05-08T01:51:32.362069Z        30 Query     SHOW TABLES FROM `replcrash` LIKE 'checksums'
2018-05-08T01:51:32.364738Z        30 Query     CREATE TABLE IF NOT EXISTS `replcrash`.`checksums` (
     db             CHAR(64)     NOT NULL,
     tbl            CHAR(64)     NOT NULL,
     chunk          INT          NOT NULL,
     chunk_time     FLOAT            NULL,
     chunk_index    VARCHAR(200)     NULL,
     lower_boundary TEXT             NULL,
     upper_boundary TEXT             NULL,
     this_crc       CHAR(40)     NOT NULL,
     this_cnt       INT          NOT NULL,
     master_crc     CHAR(40)         NULL,
     master_cnt     INT              NULL,
     ts             TIMESTAMP    NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
     PRIMARY KEY (db, tbl, chunk),
     INDEX ts_db_tbl (ts, db, tbl)
  ) ENGINE=InnoDB DEFAULT CHARSET=utf8
2018-05-08T01:51:32.920625Z        30 Query     SHOW GLOBAL STATUS LIKE 'Threads_running'
2018-05-08T01:51:32.924636Z        30 Query     SELECT CONCAT(@@hostname, @@port)
...

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若是遇到相似問題，建議開啓general_log，查看處理過程，再覈驗到底什麼緣由致使檢測不出主從差別數據(･ω･)

---

09:21 2018/5/10 補充，其實能夠在命令行帶上--set-vars binlog_format='statement'
詳細說明參考：pt-table-checksum not detecting diffs

[root@ZST2 ~]# /usr/local/bin/pt-table-checksum --nocheck-binlog-format --nocheck-replication-filters --recursion-method=hosts --replicate=replcrash.checksums --databases=replcrash --tables=py_user,py_user_innodb --host=192.168.85.132 --port=3306 --user=mydba --password=mysql5721 --set-vars binlog_format='statement'
            TS ERRORS  DIFFS     ROWS  CHUNKS SKIPPED    TIME TABLE
05-10T09:25:01      0      1       11       1       0   0.024 replcrash.py_user
05-10T09:25:01      0      0    67740       5       0   0.695 replcrash.py_user_innodb
[root@ZST2 ~]# 

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