Galera/mysql 叢集 備忘
特色
MySQL/Galera 是一種多主同步叢集，但只限於使用 MySQL/InnoDB 引擎，並具有下面特點
同步複製
多個主伺服器的拓撲結構
可以在任意節點上進行讀寫
自動控制成員，自動刪除故障節點
自動加入節點
真正給予行級別的併發複製
排程客戶連線
優勢
參考下面基於 DBMS 叢集的解決方法
不存在從伺服器角色
不存在事務丟失
讀寫操作可根據需要進行隨意擴充套件
更少的閂操作
是否可以使用 MySQL 而不使用 mariadb?
不可以，因為 mysql 中沒有支援 wsrep_ 資料複製的引數，當然程式碼級別上也具有很大差別
工作原理
mariadb 可以看做是常見的資料庫，負責連線應用(web, API 等）
單純的 mariadb 無法實現多個主伺服器資料同步
多臺資料庫中資料同步由 wsrep 介面實現
最終目標，實現多個 MySQL 同時讀寫
wsrep API
wsrep API 是一種資料庫外掛介面，比較類似一種應用程式，主要針對寫複製
該程式主要用於定義應用程式如何呼叫複製庫實現回寫
wsrep API 由支援改庫的應用程式動態裝載
全域性事務ID(GTID)
wsrep API 描述下面複製模型，一個應用程式，如資料庫當前的一個物件，當前被客戶端修改，物件改變導致事務產生一系列的原子性改變， 在叢集中所有的節點都具備相同的物件，並由同步複製應用都各自節點，按照相同的順序產生相同變化從而實現資料同步
到最後，wsrep API 將會分配一個全域性事務ID 該 ID 具有下面功能
標識物件的改變
標識物件自身 ID 最後狀態（正常情況下，ID 是連續不中斷的）
GTID 包含
一個 UUID 作為物件標識及經歷改變的序號，序號會發生連續的改變
GTID 允許比較應用程式狀態，建立物件改變的順序，決定物件的變化是否需要更新 GTID
通常 GTID 會卑記錄成下面格式
45eec521-2f34-11e0-0800-2a36050b826b:94530586304
言歸正傳，我們需要編譯 mariadb-mysql 及 galera 外掛
galera/mysql 編譯步驟
yum install -y cmake
tar xf mariadb-galera-5.5.33a.tar.gz
cd mariadb-5.5.33a/
cmake -LAH
參考 CMakeCache.txt 檔案中的配置資訊
cmake -DINSTALL_MYSQLDATADIR:STRING=/mdb -DINSTALL_UNIX_ADDRDIR:STRING=/var/run/mysqld/mysql5.socket
make
make install
預設情況下， mariadb 安裝在 /usr/local/mysql
galera 編譯
新增資料來源
baseurl=http://mirror.neu.edu.cn/fedora/epel//6Server/x86_64/新增下面軟體包
yum erase -y mysql.x86_64 mysql-devel.x86_64 mysql-libs.x86_64
yum install -y boost-devel.x86_64 libodb-boost-devel.x86_64 bzr scons
解壓 galera-23.2.7-src.tar.gz 並進行編譯
cd /usr/src
tar xf galera-23.2.7-src.tar.gz
cd galera-23.2.7-src
scons
注: scons 為編譯命令
編譯後能生成 libgalera_smm.so
複製編譯好的庫至下面位置 /usr/local/galera/lib/libgalera_smm.so
mkdir /usr/local/galera/lib -p
cp /usr/src/galera-23.2.7-src/libgalera_smm.so /usr/local/galera/lib/libgalera_smm.so
複製 啟動指令碼 /usr/src/galera-23.2.7-src/scripts/mysql/mysql-galera 到 /usr/local
cp /usr/src/galera-23.2.7-src/scripts/mysql/mysql-galera /usr/local
建立 /usr/local/mysql/etc/my.cnf
[mysqld]
basedir=/usr/local/mysql
big-tables
bind-address=0.0.0.0
character-set-server=utf8
datadir=/mdb
log-error=/var/log/mysqld/mysql5-error.log
socket=/var/run/mysqld/mysql5.socket
pid-file=/var/run/mysqld/mysql5.pid
port=3306
user=mysql
binlog_format = ROW
binlog_cache_size = 1M
character_set_server = utf8
collation_server = utf8_general_ci
default-storage-engine = InnoDB
expire_logs_days = 10
innodb_buffer_pool_size = 300M
innodb_thread_concurrency = 16
innodb_log_buffer_size = 8M
innodb_doublewrite = 1
innodb_file_per_table = 1
innodb_flush_log_at_trx_commit = 2
server-id = 1
max_connections = 1000
net_buffer_length = 8K
open-files-limit = 65535
wsrep_cluster_address = 'gcomm://192.168.200.163,192.168.200.171,172.18.8.49，172.18.8.50'
wsrep_provider = /usr/local/galera/lib/libgalera_smm.so
wsrep_retry_autocommit = 0
wsrep_sst_method = rsync
wsrep_provider_options="gcache.size=256m; gcache.page_size=256m"
wsrep_slave_threads=16
wsrep_cluster_name='my_cluster'
wsrep_node_name='db5'
wsrep_sst_auth=tt:tt123
maridb 啟動測試
初始化資料庫
mkdir /mdb
cd /usr/local/mysql
./scripts/install_mysql_db --datadir=/mdb
啟動指令碼 /etc/rc.d/init.d/mysql5 確保檔案可執行許可權
#!/bin/sh
# chkconfig: 2345 64 36
# description: A very fast and reliable SQL database engine.
basedir=/usr/local/mysql datadir=/mdb
# Default value, in seconds, afterwhich the script should timeout waiting # for server start. # Value here is overriden by value in my.cnf. # 0 means don't wait at all # Negative numbers mean to wait indefinitely service_startup_timeout=900 startup_sleep=1
# Lock directory for RedHat / SuSE. lockdir='/var/lock/subsys' lock_file_path="$lockdir/mysql"
# The following variables are only set for letting mysql.server find things.
# Set some defaults mysqld_pid_file_path=/var/run/mysqld/mysql5.pid if test -z "$basedir" then basedir=/usr/local/mysql bindir=/usr/local/mysql/bin if test -z "$datadir" then datadir=/usr/local/mysql/data fi sbindir=/usr/local/mysql/bin libexecdir=/usr/local/mysql/bin
else bindir="$basedir/bin" if test -z "$datadir" then datadir="$basedir/data" fi sbindir="$basedir/sbin" if test -f "$basedir/bin/mysqld" then libexecdir="$basedir/bin" else libexecdir="$basedir/libexec" fi fi
# datadir_set is used to determine if datadir was set (and so should be # *not* set inside of the --basedir= handler.) datadir_set=
# # Use LSB init script functions for printing messages, if possible # lsb_functions="/lib/lsb/init-functions" if test -f $lsb_functions ; then . $lsb_functions else log_success_msg() { echo " SUCCESS! [email protected]" } log_failure_msg() { echo " ERROR! [email protected]" } fi
PATH="/sbin:/usr/sbin:/bin:/usr/bin:$basedir/bin"
export PATH
mode=$1 # start or stop
[ $# -ge 1 ] && shift
other_args="$*" # uncommon, but needed when called from an RPM upgrade action # Expected: "--skip-networking --skip-grant-tables" # They are not checked here, intentionally, as it is the resposibility # of the "spec" file author to give correct arguments only.
case `echo "testing\c"`,`echo -n testing` in *c*,-n*) echo_n= echo_c= ;; *c*,*) echo_n=-n echo_c= ;; *) echo_n= echo_c='\c' ;; esac
parse_server_arguments() { for arg do case "$arg" in --basedir=*) basedir=`echo "$arg" | sed -e 's/^[^=]*=//'` bindir="$basedir/bin" if test -z "$datadir_set"; then datadir="$basedir/data" fi sbindir="$basedir/sbin" if test -f "$basedir/bin/mysqld" then libexecdir="$basedir/bin" else libexecdir="$basedir/libexec" fi libexecdir="$basedir/libexec" ;; --datadir=*) datadir=`echo "$arg" | sed -e 's/^[^=]*=//'` datadir_set=1
;; --pid-file=*) mysqld_pid_file_path=`echo "$arg" | sed -e 's/^[^=]*=//'` ;; --service-startup-timeout=*) service_startup_timeout=`echo "$arg" | sed -e 's/^[^=]*=//'` ;; esac done }
wait_for_pid () { verb="$1" # created | removed pid="$2" # process ID of the program operating on the pid-file pid_file_path="$3" # path to the PID file.
sst_progress_file=$datadir/sst_in_progress i=0 avoid_race_condition="by checking again"
while test $i -ne $service_startup_timeout ; do
case "$verb" in 'created') # wait for a PID-file to pop into existence. test -s "$pid_file_path" && i='' && break ;; 'removed') # wait for this PID-file to disappear test ! -s "$pid_file_path" && i='' && break ;; *) echo "wait_for_pid () usage: wait_for_pid created|removed pid pid_file_path" exit 1 ;; esac
# if server isn't running, then pid-file will never be updated if test -n "$pid"; then if kill -0 "$pid" 2>/dev/null; then : # the server still runs
else # The server may have exited between the last pid-file check and now. if test -n "$avoid_race_condition"; then avoid_race_condition="" continue # Check again. fi
# there's nothing that will affect the file. log_failure_msg "The server quit without updating PID file ($pid_file_path)." return 1 # not waiting any more. fi fi
if test -e $sst_progress_file && [ $startup_sleep -ne 100 ];then echo $echo_n "SST in progress, setting sleep higher" startup_sleep=100 fi
echo $echo_n ".$echo_c" i=`expr $i + 1` sleep $startup_sleep
done
if test -z "$i" ; then log_success_msg return 0 else log_failure_msg return 1 fi }
# Get arguments from the my.cnf file, # the only group, which is read from now on is [mysqld] if test -x ./bin/my_print_defaults then
print_defaults="./bin/my_print_defaults" elif test -x $bindir/my_print_defaults then print_defaults="$bindir/my_print_defaults" elif test -x $bindir/mysql_print_defaults then print_defaults="$bindir/mysql_print_defaults" else # Try to find basedir in /etc/my.cnf conf=/usr/local/mysql/etc/my.cnf print_defaults= if test -r $conf then subpat='^[^=]*basedir[^=]*=\(.*\)$' dirs=`sed -e "/$subpat/!d" -e 's//\1/' $conf` for d in $dirs do d=`echo $d | sed -e 's/[ ]//g'` if test -x "$d/bin/my_print_defaults" then print_defaults="$d/bin/my_print_defaults" break fi if test -x "$d/bin/mysql_print_defaults" then print_defaults="$d/bin/mysql_print_defaults" break fi done fi
# Hope it's in the PATH ... but I doubt it test -z "$print_defaults" && print_defaults="my_print_defaults" fi
# # Read defaults file from 'basedir'. If there is no defaults file there
# check if it's in the old (depricated) place (datadir) and read it from there #
extra_args="" if test -r "$basedir/my.cnf" then extra_args="-e $basedir/my.cnf" else if test -r "$datadir/my.cnf" then extra_args="-e $datadir/my.cnf" fi fi
parse_server_arguments `$print_defaults $extra_args mysqld server mysql_server mysql.server`
# # Set pid file if not given # if test -z "$mysqld_pid_file_path" then mysqld_pid_file_path=$datadir/`hostname`.pid else case "$mysqld_pid_file_path" in /* ) ;; * ) mysqld_pid_file_path="$datadir/$mysqld_pid_file_path" ;; esac fi
case "$mode" in 'start') # Start daemon
# Safeguard (relative paths, core dumps..) cd $basedir
echo $echo_n "Starting MySQL"
if test -x $bindir/mysqld_safe then # Give extra arguments to mysqld with the my.cnf file. This script # may be overwritten at next upgrade. $bindir/mysqld_safe --datadir="$datadir" --pid-file="$mysqld_pid_file_path" $other_args >/dev/null 2>&1 & wait_for_pid created "$!" "$mysqld_pid_file_path"; return_value=$?
# Make lock for RedHat / SuSE if test -w "$lockdir" then touch "$lock_file_path" fi
exit $return_value else log_failure_msg "Couldn't find MySQL server ($bindir/mysqld_safe)" fi ;;
'stop') # Stop daemon. We use a signal here to avoid having to know the # root password.
if test -s "$mysqld_pid_file_path" then mysqld_pid=`cat "$mysqld_pid_file_path"`
if (kill -0 $mysqld_pid 2>/dev/null) then echo $echo_n "Shutting down MySQL" kill $mysqld_pid # mysqld should remove the pid file when it exits, so wait for it. wait_for_pid removed "$mysqld_pid" "$mysqld_pid_file_path"; return_value=$? else log_failure_msg "MySQL server process #$mysqld_pid is not running!" rm "$mysqld_pid_file_path" fi
# Delete lock for RedHat / SuSE if test -f "$lock_file_path" then rm -f "$lock_file_path" fi exit $return_value else log_failure_msg "MySQL server PID file could not be found!" fi ;;
'restart') # Stop the service and regardless of whether it was # running or not, start it again. if $0 stop $other_args; then $0 start $other_args else log_failure_msg "Failed to stop running server, so refusing to try to start." exit 1 fi ;;
'reload'|'force-reload') if test -s "$mysqld_pid_file_path" ; then read mysqld_pid < "$mysqld_pid_file_path" kill -HUP $mysqld_pid && log_success_msg "Reloading service MySQL" touch "$mysqld_pid_file_path" else log_failure_msg "MySQL PID file could not be found!" exit 1 fi ;; 'status') # First, check to see if pid file exists if test -s "$mysqld_pid_file_path" ; then read mysqld_pid < "$mysqld_pid_file_path"
if kill -0 $mysqld_pid 2>/dev/null ; then log_success_msg "MySQL running ($mysqld_pid)" exit 0 else log_failure_msg "MySQL is not running, but PID file exists" exit 1 fi else # Try to find appropriate mysqld process mysqld_pid=`pidof $libexecdir/mysqld`
# test if multiple pids exist pid_count=`echo $mysqld_pid | wc -w` if test $pid_count -gt 1 ; then log_failure_msg "Multiple MySQL running but PID file could not be found ($mysqld_pid)" exit 5 elif test -z $mysqld_pid ; then if test -f "$lock_file_path" ; then log_failure_msg "MySQL is not running, but lock file ($lock_file_path) exists" exit 2 fi log_failure_msg "MySQL is not running" exit 3 else log_failure_msg "MySQL is running but PID file could not be found" exit 4 fi fi ;; 'configtest') # Safeguard (relative paths, core dumps..) cd $basedir echo $echo_n "Testing MySQL configuration syntax" daemon=$bindir/mysqld if test -x $libexecdir/mysqld then daemon=$libexecdir/mysqld elif test -x $sbindir/mysqld then daemon=$sbindir/mysqld elif test -x `which mysqld` then daemon=`which mysqld` else log_failure_msg "Unable to locate the mysqld binary!" exit 1 fi help_out=`$daemon --help 2>&1`; r=$? if test "$r" != 0 ; then log_failure_msg "$help_out" log_failure_msg "There are syntax errors in the server configuration. Please fix them!" else log_success_msg "Syntax OK" fi exit $r ;; 'bootstrap') # Bootstrap the cluster, start the first node # that initiate the cluster echo $echo_n "Bootstrapping the cluster" $0 start $other_args --wsrep-new-cluster ;; *) # usage basename=`basename "$0"` echo "Usage: $basename {start|stop|restart|reload|force-reload|status|configtest|bootstrap} [ MySQL server options ]" exit 1 ;; esac
exit 0
啟動每一臺資料庫
service mysql5 start
在每臺數據庫中建立下面使用者， 用於 sst 認證 (以 root 登入 mysql 資料庫後執行下面的 SQL 語句)
GRANT USAGE ON *.* to [email protected]'%' IDENTIFIED BY 'tt123';
GRANT ALL PRIVILEGES on *.* to [email protected]'%';
GRANT USAGE ON *.* to [email protected]'localhost' IDENTIFIED BY 'tt123';
GRANT ALL PRIVILEGES on *.* to [email protected]'localhost';
flush privileges;
關閉所有資料庫, 叢集啟動前， 不需要啟動任何一臺的資料庫
service mysql5 stop
建立並加入叢集
叢集中第一個節點啟動 (192.168.200.163)
建立軟連結，並啟動叢集，叢集啟動過程中會自動啟動 mariadb
ln -s /usr/local/mysql/bin/ /usr/local/mysql/sbin
cd /usr/local/
./mysql-galera -g gcomm:// start測試是否成功啟動方法, 查詢是否會自動啟動 4567 埠
[[email protected] local]# netstat -ntl
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 0.0.0.0:3306 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:4567 0.0.0.0:* LISTEN
登入 mysql 之後，查詢當前是否啟用 galera 外掛
MariaDB [(none)]> show status like 'wsrep_ready';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| wsrep_ready | ON |
+---------------+-------+
1 row in set (0.00 sec)
注，on 為已經啟動外掛狀態
關閉方法
cd /usr/local
./mysql-galera stop
其他節點加入叢集方法
第一臺 (192.168.200.163) 節點已經啟動成功
第二臺 (192.168.200.171) 需要加入叢集
cd /usr/local/
./mysql-galera -g gcomm://192.168.200.163 start
可按上述方法進行叢集啟動測試, 也可以參照下面方法, 觀察叢集地址是否增加兩個伺服器地址
MariaDB [(none)]> show status like 'wsrep_incoming_addresses';
+--------------------------+-------------------------------------------+
| Variable_name | Value |
+--------------------------+-------------------------------------------+
| wsrep_incoming_addresses | 192.168.200.171:3306,192.168.200.163:3306 |
+--------------------------+-------------------------------------------+
1 row in set (0.00 sec)
第三臺 (172.18.8.49) 需要加入叢集
cd /usr/local/
./mysql-galera -g gcomm://192.168.200.163,192.168.200.171 start
第四臺 (172.18.8.50) 需要加入叢集
cd /usr/local/
./mysql-galera -g gcomm://192.168.200.163,192.168.200.171,172.18.8.49 start注: 每次叢集啟動， 將會啟用資料同步機制，令每個叢集中的資料同步
假如，叢集工作期間，節點 3(172.18.8.49) 脫離叢集，重啟，發生故障
而離線期間，節點1,2,4 仍可繼續工作
當節點3 重新線上時，加入叢集前，將會自動進行資料同步
重新線上方法與上文中加入節點方法一致
另外，假如覺得要定義所有的伺服器地址麻煩，可以加入叢集時候只定義其中一臺的地址，如 gcomm://192.168.200.163 叢集也能夠自動在加入後新增其他叢集 url地址
常見 wsrep 引數註釋
MariaDB [terry]> show status like 'wsrep%';
+----------------------------+--------------------------------------+
| Variable_name | Value |
+----------------------------+--------------------------------------+
| wsrep_local_state_uuid | bb5b9e17-66c8-11e3-86ba-96854521d205 | uuid 叢集唯一標記
| wsrep_protocol_version | 4 |
| wsrep_last_committed | 16 | sql 提交記錄
| wsrep_replicated | 4 | 隨著複製發出的次數
| wsrep_replicated_bytes | 692 | 資料複製發出的位元組數
| wsrep_received | 18 | 資料複製接收次數
| wsrep_received_bytes | 3070 | 資料複製接收的位元組數
| wsrep_local_commits | 4 | 本地執行的 sql
| wsrep_local_cert_failures | 0 | 本地失敗事務
| wsrep_local_bf_aborts | 0 |從執行事務過程被本地中斷
| wsrep_local_replays | 0 |
| wsrep_local_send_queue | 0 | 本地發出的佇列
| wsrep_local_send_queue_avg | 0.142857 | 佇列平均時間間隔
| wsrep_local_recv_queue | 0 | 本地接收佇列
| wsrep_local_recv_queue_avg | 0.000000 | 本地接收時間間隔
| wsrep_flow_control_paused | 0.000000 |
| wsrep_flow_control_sent | 0 |
| wsrep_flow_control_recv | 0 |
| wsrep_cert_deps_distance | 0.000000 | 併發數量
| wsrep_apply_oooe | 0.000000 |
| wsrep_apply_oool | 0.000000 |
| wsrep_apply_window | 1.000000 |
| wsrep_commit_oooe | 0.000000 |
| wsrep_commit_oool | 0.000000 |
| wsrep_commit_window | 1.000000 |
| wsrep_local_state | 4 |
| wsrep_local_state_comment | Synced |
| wsrep_cert_index_size | 0 |
| wsrep_causal_reads | 0 |
| wsrep_incoming_addresses | 172.18.8.50:3306,172.18.8.49:3306 | 連線中的資料庫
| wsrep_cluster_conf_id | 18 |
| wsrep_cluster_size | 2 | 叢集成員個數
| wsrep_cluster_state_uuid | bb5b9e17-66c8-11e3-86ba-96854521d205 | 叢集 ID
| wsrep_cluster_status | Primary | 主伺服器
| wsrep_connected | ON | 當前是否連線中
| wsrep_local_index | 1 |
| wsrep_provider_name | Galera |
| wsrep_provider_vendor | Codership Oy <[email protected]> |
| wsrep_provider_version | 2.7(rXXXX) |
| wsrep_ready | ON | 外掛是否應用中
+----------------------------+--------------------------------------+
40 rows in set (0.05 sec)
時間關係，還沒有時間進行壓力測試，也沒有比對 galera 與 Percona XtraDB Cluster 叢集之間區別
另，如使用 rpm 則十分方便，網路很多教程， 不詳細描述
auto_increment
當更多的 MariaDB 加入到叢集之後，叢集中的資料庫會自動進行協調，並且自動定義偏移量， 這個比較人性化，自動化，如下描述
db1:
MariaDB [(none)]> show variables like 'auto_increment%';
+--------------------------+-------+
| Variable_name | Value |
+--------------------------+-------+
| auto_increment_increment | 4 |
| auto_increment_offset | 3 |
+--------------------------+-------+
2 rows in set (0.00 sec)
db2:
MariaDB [(none)]> show variables like 'auto_increment%';
+--------------------------+-------+
| Variable_name | Value |
+--------------------------+-------+
| auto_increment_increment | 4 |
| auto_increment_offset | 4 |
+------------------------
db3:
MariaDB [(none)]> show variables like 'auto_increment%';
+--------------------------+-------+
| Variable_name | Value |
+--------------------------+-------+
| auto_increment_increment | 4 |
| auto_increment_offset | 2 |
+--------------------------+-------+
2 rows in set (0.00 sec)
db4:
MariaDB [(none)]> show variables like 'auto_increment%';
+--------------------------+-------+
| Variable_name | Value |
+--------------------------+-------+
| auto_increment_increment | 4 |
| auto_increment_offset | 1 |
+--------------------------+-------+
2 rows in set (0.00 sec)
當前加入叢集中共 4 個節點， 如上所見，每個叢集中都會每次在數字遞增時候遞增 4 位， 而數字起始值為加入叢集的順序
模擬測試1
建立測試表
MariaDB [(none)]> desc terry.t2;
+-------+-------------+------+-----+-------------------+-----------------------------+
| Field | Type | Null | Key | Default | Extra |
+-------+-------------+------+-----+-------------------+-----------------------------+
| id | int(11) | NO | PRI | NULL | auto_increment |
| name | varchar(20) | YES | | NULL | |
| time | timestamp | NO | | CURRENT_TIMESTAMP | on update CURRENT_TIMESTAMP |
+-------+-------------+------+-----+-------------------+-----------------------------+
3 rows in set (0.00 sec)
在每臺電腦中建立對應的資料插入指令碼 (太大量的併發插入會導致伺服器不斷脫離叢集，最終只剩下一次，因此減少資料插入量)
[[email protected] mdb]# cat /tmp/in.sh
#!/bin/bash
for (( a=1 ; a<=1000 ; a++ ))
do
name="db6.$a"
mysql -u terry -p123 -e "insert into terry.t2 (name, time) values (\"$name\", now())"
done
目的：同時在 4 臺電腦中進行資料插入，每臺插入 1000 行（併發執行)
插入過程中, 會出現鎖，有一個數據庫叢集會自動脫離叢集 >_<"
MySQL thread id 16, OS thread handle 0x7f2f2019a700, query id 4666 applied write set 183192
TABLE LOCK table `terry`.`t2` trx id 2D3EF lock mode IX
---TRANSACTION 2D3EE, ACTIVE 0 sec
mysql tables in use 1, locked 1
1 lock struct(s), heap size 376, 0 row lock(s), undo log entries 1
MySQL thread id 633, OS thread handle 0x7f2f20076700, query id 4664 localhost terry query end
insert into terry.t2 (name, time) values ("db5.603", now())
TABLE LOCK table `terry`.`t2` trx id 2D3EE lock mode IX
---TRANSACTION 2D3ED, ACTIVE (PREPARED) 0 sec preparing
1 lock struct(s), heap size 376, 0 row lock(s), undo log entries 1
MySQL thread id 3, OS thread handle 0x7f2f3be4e700, query id 4662 committing 183190參考其他三臺 時間返回值
db1 (使用 13 秒)
db2 (使用 24秒)
db3(使用14秒)
db4(寫入 35 條資料後 crash)