pxc优点总结：

可以达到时时同步，无延迟现象发生

完全兼容MySQL

对于集群中新节点的加入，维护起来很简单

数据的强一致性

不足之处总结：

只支持Innodb存储引擎

存在多节点update更新问题，也就是写放大问题

在线DDL语句，锁表问题

sst针对新节点加入的传输代价过高的问题

关于写放大的原理图

下面从上次组复制转pxc

https://www.cnblogs.com/omsql/p/9277047.html

pxc架构图如下

卸载mysql

卸载前记得备份my.cnf

yum remove mysql-community-*

安装pxc

yum install http://www.percona.com/downloads/percona-release/redhat/0.1-6/percona-release-0.1-6.noarch.rpm

yum install http://rpmfind.net/linux/dag/redhat/el6/en/x86_64/dag/RPMS/socat-1.7.2.4-1.el6.rf.x86_64.rpm

yum install Percona-XtraDB-Cluster-57

修改my.cnf

#pxc

wsrep_provider=/usr/lib64/galera3/libgalera_smm.so

wsrep_cluster_address=gcomm://192.168.20.201,192.168.20.202,192.168.20.203

wsrep_slave_threads= 8

innodb_autoinc_lock_mode=2

wsrep_node_address=192.168.20.201

wsrep_cluster_name=ht-pxc-cluster

wsrep_node_name=pxc01

pxc_strict_mode=ENFORCING

wsrep_sst_method=xtrabackup-v2

wsrep_sst_auth=sst:ocm123

第一个节点启动

/etc/init.d/mysqld bootstrap-pxc

创建用户

SHOW VARIABLES LIKE 'validate_password%';

set global validate_password_policy=LOW;

set global validate_password_length=4;

create user 'sst'@'localhost' identified by 'ocm123';

grant all privileges on *.* to 'sst'@'localhost' identified by 'ocm123';

flush privileges;

第二个节点启动

/etc/init.d/mysql start

第三个节点启动

/etc/init.d/mysql start

添加第三个节点redis03的时候redis02日志输出如下

1 redis022 2018-07-09T15:01:19.004758Z 0 [Note] WSREP: Member 2.0 (pxc03) requested state transfer from '*any*'. Selected 0.0 (pxc02)(SYNCED) asdonor.3 2018-07-09T15:01:19.004800Z 0 [Note] WSREP: Shifting SYNCED -> DONOR/DESYNCED (TO: 7054)4 2018-07-09T15:01:19.004867Z 5 [Note] WSREP: wsrep_notify_cmd isnot defined, skipping notification.5 2018-07-09T15:01:19.005039Z 0 [Note] WSREP: Initiating SST/IST transfer on DONOR side (wsrep_sst_xtrabackup-v2 --role 'donor' --address '192.168.20.203:4444/xtrabackup_sst//1' --socket '/data/mysql/mysql.sock' --datadir '/data/mysql/' --defaults-file '/etc/my.cnf' --defaults-group-suffix '' --binlog 'mysql-bin' --gtid '62e9006b-8379-11e8-bc64-874d49a77c07:7054')6 2018-07-09T15:01:19.087469Z 5 [Note] WSREP: DONOR thread signaled with 0

View Code

redis02被选为donar，使用xtrabackup备份整个库传到redis03下，同时查看redis03  /data/mysql

[root@redis03 mysql]# ls

galera.cache grastate.dat gvwstate.dat sst_in_progress

恢复完后如下

1 [root@redis03 mysql]# ls2 auto.cnf grastate.dat ib_logfile1 mysql-bin.000007 public_key.pem server-cert.pem xtrabackup_info3 ca-key.pem gvwstate.dat ibtmp1 mysql-bin.index pxc server-key.pem xtrabackup_master_key_id4 ca.pem ht innobackup.move.log mysql.sock redis03-relay-bin-group_replication_applier.000001sys5 client-cert.pem ib_buffer_pool innobackup.prepare.log mysql.sock.lock redis03-relay-bin-group_replication_applier.index xb_doublewrite6 client-key.pem ibdata1 mysql performance_schema redis03-relay-bin-group_replication_recovery.000001xtrabackup_binlog_pos_innodb7 galera.cache ib_logfile0 mysql-bin.000006 private_key.pem redis03-relay-bin-group_replication_recovery.index xtrabackup_galera_info

上面输出可以看出sst针对新节点加入的传输代价过高。

查看集群状态

root@redis03> show status like 'wsrep%';+----------------------------------+-------------------------------------------------------------+

| Variable_name | Value |

+----------------------------------+-------------------------------------------------------------+

| wsrep_local_state_uuid | 62e9006b-8379-11e8-bc64-874d49a77c07 |

| wsrep_protocol_version | 8 |

| wsrep_last_applied | 7054 |

| wsrep_last_committed | 7054 |

| wsrep_replicated | 0 |

| wsrep_replicated_bytes | 0 |

| wsrep_repl_keys | 0 |

| wsrep_repl_keys_bytes | 0 |

| wsrep_repl_data_bytes | 0 |

| wsrep_repl_other_bytes | 0 |

| wsrep_received | 2 |

| wsrep_received_bytes | 285 |

| wsrep_local_commits | 0 |

| wsrep_local_cert_failures | 0 |

| wsrep_local_replays | 0 |

| wsrep_local_send_queue | 0 |

| wsrep_local_send_queue_max | 1 |

| wsrep_local_send_queue_min | 0 |

| wsrep_local_send_queue_avg | 0.000000 |

| wsrep_local_recv_queue | 0 |

| wsrep_local_recv_queue_max | 1 |

| wsrep_local_recv_queue_min | 0 |

| wsrep_local_recv_queue_avg | 0.000000 |

| wsrep_local_cached_downto | 0 |

| wsrep_flow_control_paused_ns | 0 |

| wsrep_flow_control_paused | 0.000000 |

| wsrep_flow_control_sent | 0 |

| wsrep_flow_control_recv | 0 |

| wsrep_flow_control_interval | [ 173, 173 ] |

| wsrep_flow_control_interval_low | 173 |

| wsrep_flow_control_interval_high | 173 |

| wsrep_flow_control_status | OFF |

| wsrep_cert_deps_distance | 0.000000 |

| wsrep_apply_oooe | 0.000000 |

| wsrep_apply_oool | 0.000000 |

| wsrep_apply_window | 0.000000 |

| wsrep_commit_oooe | 0.000000 |

| wsrep_commit_oool | 0.000000 |

| wsrep_commit_window | 0.000000 |

| wsrep_local_state | 4 |

| wsrep_local_state_comment | Synced |

| wsrep_cert_index_size | 0 |

| wsrep_cert_bucket_count | 22 |

| wsrep_gcache_pool_size | 1320 |

| wsrep_causal_reads | 0 |

| wsrep_cert_interval | 0.000000 |

| wsrep_ist_receive_status | |

| wsrep_ist_receive_seqno_start | 0 |

| wsrep_ist_receive_seqno_current | 0 |

| wsrep_ist_receive_seqno_end | 0 |

| wsrep_incoming_addresses | 192.168.20.202:3306,192.168.20.201:3306,192.168.20.203:3306 |

| wsrep_desync_count | 0 |

| wsrep_evs_delayed | |

| wsrep_evs_evict_list | |

| wsrep_evs_repl_latency | 0/0/0/0/0 |

| wsrep_evs_state | OPERATIONAL |

| wsrep_gcomm_uuid | ee9c63ef-8388-11e8-af36-8bf4f2f07974 |

| wsrep_cluster_conf_id | 5 |

| wsrep_cluster_size | 3 |

| wsrep_cluster_state_uuid | 62e9006b-8379-11e8-bc64-874d49a77c07 |

| wsrep_cluster_status | Primary |

| wsrep_connected | ON |

| wsrep_local_bf_aborts | 0 |

| wsrep_local_index | 2 |

| wsrep_provider_name | Galera |

| wsrep_provider_vendor | Codership Oy |

| wsrep_provider_version | 3.26(rac090bc) |

| wsrep_ready | ON |

+----------------------------------+-------------------------------------------------------------+

View Code

在对pxc做此oltp测试

安装sysbench

yum install sysbench

生成数据，创建10个表，每个表百万行

sysbench oltp_common --tables=10 --table-size=1000000 --db-driver=mysql --mysql-db=pxc --mysql-user=root --mysql-password=ocm123 prepare

oltp 测试，开启50个并行

sysbench oltp_read_write.lua --db-driver=mysql --mysql-host=127.0.0.1 --mysql-port=3306 --mysql-db=pxc --mysql-user=root --mysql-password=ocm123 --table_size=1000000 --tables=10 --threads=50 --report-interval=10 --time=300 run

oltp测试结果如下

1 [root@redis01 sysbench]# sysbench oltp_read_write.lua --db-driver=mysql --mysql-host=127.0.0.1 --mysql-port=3306 --mysql-db=pxc --mysql-user=root --mysql-password=ocm123 --table_size=1000000 --tables=10 --threads=50 --report-interval=10 --time=300run2 sysbench 1.0.14 (using bundled LuaJIT 2.1.0-beta2)3

4 Running the test with following options:5 Number of threads: 50

6 Report intermediate results every 10second(s)7 Initializing random number generator fromcurrent time8

9

10 Initializing worker threads...11

12 Threads started!

13

14 [ 10s ] thds: 50 tps: 7.90 qps: 231.92 (r/w/o: 168.04/26.19/37.69) lat (ms,95%): 5813.24 err/s: 0.00 reconn/s: 0.00

15 [ 20s ] thds: 50 tps: 11.80 qps: 254.99 (r/w/o: 177.69/32.30/45.00) lat (ms,95%): 5918.87 err/s: 0.00 reconn/s: 0.00

16 [ 30s ] thds: 50 tps: 8.90 qps: 179.97 (r/w/o: 124.58/26.10/29.30) lat (ms,95%): 6476.48 err/s: 0.00 reconn/s: 0.00

17 [ 40s ] thds: 50 tps: 10.40 qps: 175.17 (r/w/o: 122.35/19.81/33.01) lat (ms,95%): 9284.15 err/s: 0.00 reconn/s: 0.00

18 [ 50s ] thds: 50 tps: 9.20 qps: 182.49 (r/w/o: 131.10/21.90/29.50) lat (ms,95%): 9799.46 err/s: 0.00 reconn/s: 0.00

19 [ 60s ] thds: 50 tps: 8.80 qps: 198.65 (r/w/o: 140.97/24.39/33.29) lat (ms,95%): 7215.39 err/s: 0.00 reconn/s: 0.00

20 [ 70s ] thds: 50 tps: 7.00 qps: 145.72 (r/w/o: 99.01/21.60/25.10) lat (ms,95%): 8795.93 err/s: 0.00 reconn/s: 0.00

21 [ 80s ] thds: 50 tps: 13.70 qps: 239.41 (r/w/o: 171.21/27.20/41.00) lat (ms,95%): 8484.79 err/s: 0.00 reconn/s: 0.00

22 [ 90s ] thds: 50 tps: 7.40 qps: 161.92 (r/w/o: 107.41/24.90/29.60) lat (ms,95%): 8484.79 err/s: 0.00 reconn/s: 0.00

23 [ 100s ] thds: 50 tps: 8.00 qps: 186.69 (r/w/o: 130.99/24.00/31.70) lat (ms,95%): 5918.87 err/s: 0.00 reconn/s: 0.00

24 [ 110s ] thds: 50 tps: 10.00 qps: 200.01 (r/w/o: 140.00/27.40/32.60) lat (ms,95%): 5709.50 err/s: 0.00 reconn/s: 0.00

25 [ 120s ] thds: 50 tps: 10.60 qps: 210.17 (r/w/o: 148.38/25.60/36.19) lat (ms,95%): 8184.67 err/s: 0.00 reconn/s: 0.00

26 [ 130s ] thds: 50 tps: 11.50 qps: 223.73 (r/w/o: 159.42/24.70/39.61) lat (ms,95%): 7895.16 err/s: 0.00 reconn/s: 0.00

27 [ 140s ] thds: 50 tps: 11.90 qps: 242.60 (r/w/o: 168.03/31.09/43.48) lat (ms,95%): 4943.53 err/s: 0.00 reconn/s: 0.00

28 [ 150s ] thds: 50 tps: 9.10 qps: 185.45 (r/w/o: 127.53/26.21/31.71) lat (ms,95%): 4517.90 err/s: 0.00 reconn/s: 0.00

29 [ 160s ] thds: 50 tps: 14.50 qps: 253.44 (r/w/o: 179.83/27.70/45.91) lat (ms,95%): 8184.67 err/s: 0.00 reconn/s: 0.00

30 [ 170s ] thds: 50 tps: 8.40 qps: 203.91 (r/w/o: 140.80/28.10/35.00) lat (ms,95%): 4943.53 err/s: 0.00 reconn/s: 0.00

31 [ 180s ] thds: 50 tps: 13.90 qps: 261.61 (r/w/o: 187.64/28.89/45.08) lat (ms,95%): 7754.26 err/s: 0.00 reconn/s: 0.00

32 [ 190s ] thds: 50 tps: 10.50 qps: 226.94 (r/w/o: 153.93/35.31/37.71) lat (ms,95%): 7754.26 err/s: 0.00 reconn/s: 0.00

33 [ 200s ] thds: 50 tps: 12.00 qps: 218.73 (r/w/o: 153.52/25.30/39.91) lat (ms,95%): 4203.93 err/s: 0.00 reconn/s: 0.00

34 [ 210s ] thds: 50 tps: 11.80 qps: 249.64 (r/w/o: 177.76/29.89/41.99) lat (ms,95%): 5607.61 err/s: 0.00 reconn/s: 0.00

35 [ 220s ] thds: 50 tps: 12.69 qps: 256.80 (r/w/o: 178.93/30.99/46.88) lat (ms,95%): 4517.90 err/s: 0.00 reconn/s: 0.00

36 [ 230s ] thds: 50 tps: 14.01 qps: 253.05 (r/w/o: 180.41/27.62/45.03) lat (ms,95%): 5709.50 err/s: 0.00 reconn/s: 0.00

37 [ 240s ] thds: 50 tps: 9.20 qps: 211.70 (r/w/o: 145.10/31.10/35.50) lat (ms,95%): 5507.54 err/s: 0.00 reconn/s: 0.00

38 [ 250s ] thds: 50 tps: 14.10 qps: 259.32 (r/w/o: 186.52/29.30/43.50) lat (ms,95%): 7086.63 err/s: 0.00 reconn/s: 0.00

39 [ 260s ] thds: 50 tps: 9.20 qps: 210.87 (r/w/o: 139.78/35.00/36.10) lat (ms,95%): 8038.61 err/s: 0.00 reconn/s: 0.00

40 [ 270s ] thds: 50 tps: 11.20 qps: 222.78 (r/w/o: 156.79/27.50/38.50) lat (ms,95%): 6026.41 err/s: 0.00 reconn/s: 0.00

41 [ 280s ] thds: 50 tps: 11.50 qps: 230.55 (r/w/o: 160.73/31.31/38.51) lat (ms,95%): 7615.89 err/s: 0.00 reconn/s: 0.00

42 [ 290s ] thds: 50 tps: 12.80 qps: 255.18 (r/w/o: 179.29/30.90/45.00) lat (ms,95%): 7086.63 err/s: 0.00 reconn/s: 0.00

43 [ 300s ] thds: 50 tps: 12.90 qps: 237.20 (r/w/o: 171.00/24.80/41.40) lat (ms,95%): 6247.39 err/s: 0.00 reconn/s: 0.00

44 SQL statistics:45 queries performed:46 read: 46186

47 write: 8348

48 other: 11446

49 total: 65980

50 transactions: 3299 (10.93per sec.)51 queries: 65980 (218.52per sec.)52 ignored errors: 0 (0.00per sec.)53 reconnects: 0 (0.00per sec.)54

55 General statistics:56 total time: 301.9413s57 total number of events: 3299

58

59 Latency (ms):60 min: 975.37

61 avg: 4575.91

62 max: 13565.48

63 95th percentile: 7479.98

64 sum: 15095927.24

65

66 Threads fairness:67 events (avg/stddev): 65.9800/1.97

68 execution time (avg/stddev): 301.9185/0.01

pxc的  qtp才为11 (虚拟机，3节点在一个磁盘上)