文章目錄
New Feature in Percona XtraDB Cluster 8.0 – Streaming Replication
Percona XtraDB Cluster 8.0附帶了一個升級的Galera 4.0庫, 它提供了一個新特性—Streaming Replication.讓我們回顧一下它是什麼, 什麼時候可能有用
以前版本的Percona XtraDB集羣和Galera 3.x在處理大事務方面有限制.
讓我們看一下sysbench-tpcc工作負載下的性能, 與此同時, 我們對一個表執行了一個大的更新語句, 該更新甚至與主工作負載中的表都不相關.
Without Streaming Replication
Let’s run two workloads.
- sysbench-tpcc workload with 1 sec resolution
- In parallel run UPDATE oltp.sbtest SET k=k+1 LIMIT 1000000
Running update:
mysql> update sbtest1 set k=k+1 limit 1000000;
Query OK, 1000000 rows affected (34.48 sec)
Rows matched: 1000000 Changed: 1000000 Warnings: 0
Check what is happening in sysbench-tpcc:
[ 77s ] thds: 100 tps: 7011.97 qps: 198248.21 (r/w/o: 90469.64/93758.63/14019.94) lat (ms,95%): 25.28 err/s 31.00 reconn/s: 0.00
[ 78s ] thds: 100 tps: 6779.94 qps: 196129.34 (r/w/o: 89462.24/93103.21/13563.88) lat (ms,95%): 26.20 err/s 30.00 reconn/s: 0.00
[ 79s ] thds: 100 tps: 6948.01 qps: 199157.35 (r/w/o: 90878.16/94383.16/13896.02) lat (ms,95%): 26.20 err/s 28.00 reconn/s: 0.00
[ 80s ] thds: 100 tps: 3920.09 qps: 113882.48 (r/w/o: 51940.13/54102.18/7840.17) lat (ms,95%): 27.17 err/s 15.00 reconn/s: 0.00
[ 81s ] thds: 100 tps: 67.00 qps: 1956.02 (r/w/o: 899.01/923.01/134.00) lat (ms,95%): 623.33 err/s 0.00 reconn/s: 0.00
[ 82s ] thds: 100 tps: 0.00 qps: 0.00 (r/w/o: 0.00/0.00/0.00) lat (ms,95%): 0.00 err/s 0.00 reconn/s: 0.00
[ 83s ] thds: 100 tps: 0.00 qps: 0.00 (r/w/o: 0.00/0.00/0.00) lat (ms,95%): 0.00 err/s 0.00 reconn/s: 0.00
[ 84s ] thds: 100 tps: 0.00 qps: 0.00 (r/w/o: 0.00/0.00/0.00) lat (ms,95%): 0.00 err/s 0.00 reconn/s: 0.00
[ 85s ] thds: 100 tps: 0.00 qps: 0.00 (r/w/o: 0.00/0.00/0.00) lat (ms,95%): 0.00 err/s 0.00 reconn/s: 0.00
[ 86s ] thds: 100 tps: 0.00 qps: 0.00 (r/w/o: 0.00/0.00/0.00) lat (ms,95%): 0.00 err/s 0.00 reconn/s: 0.00
[ 87s ] thds: 100 tps: 0.00 qps: 0.00 (r/w/o: 0.00/0.00/0.00) lat (ms,95%): 0.00 err/s 0.00 reconn/s: 0.00
[ 88s ] thds: 100 tps: 0.00 qps: 0.00 (r/w/o: 0.00/0.00/0.00) lat (ms,95%): 0.00 err/s 0.00 reconn/s: 0.00
[ 89s ] thds: 100 tps: 0.00 qps: 0.00 (r/w/o: 0.00/0.00/0.00) lat (ms,95%): 0.00 err/s 0.00 reconn/s: 0.00
[ 90s ] thds: 100 tps: 0.00 qps: 0.00 (r/w/o: 0.00/0.00/0.00) lat (ms,95%): 0.00 err/s 0.00 reconn/s: 0.00
[ 91s ] thds: 100 tps: 0.00 qps: 0.00 (r/w/o: 0.00/0.00/0.00) lat (ms,95%): 0.00 err/s 0.00 reconn/s: 0.00
[ 92s ] thds: 100 tps: 0.00 qps: 0.00 (r/w/o: 0.00/0.00/0.00) lat (ms,95%): 0.00 err/s 0.00 reconn/s: 0.00
[ 93s ] thds: 100 tps: 0.00 qps: 0.00 (r/w/o: 0.00/0.00/0.00) lat (ms,95%): 0.00 err/s 0.00 reconn/s: 0.00
[ 94s ] thds: 100 tps: 0.00 qps: 0.00 (r/w/o: 0.00/0.00/0.00) lat (ms,95%): 0.00 err/s 0.00 reconn/s: 0.00
[ 95s ] thds: 100 tps: 0.00 qps: 0.00 (r/w/o: 0.00/0.00/0.00) lat (ms,95%): 0.00 err/s 0.00 reconn/s: 0.00
[ 96s ] thds: 100 tps: 0.00 qps: 0.00 (r/w/o: 0.00/0.00/0.00) lat (ms,95%): 0.00 err/s 0.00 reconn/s: 0.00
[ 97s ] thds: 100 tps: 0.00 qps: 0.00 (r/w/o: 0.00/0.00/0.00) lat (ms,95%): 0.00 err/s 0.00 reconn/s: 0.00
[ 98s ] thds: 100 tps: 0.00 qps: 0.00 (r/w/o: 0.00/0.00/0.00) lat (ms,95%): 0.00 err/s 0.00 reconn/s: 0.00
[ 99s ] thds: 100 tps: 0.00 qps: 0.00 (r/w/o: 0.00/0.00/0.00) lat (ms,95%): 0.00 err/s 0.00 reconn/s: 0.00
[ 100s ] thds: 100 tps: 0.00 qps: 0.00 (r/w/o: 0.00/0.00/0.00) lat (ms,95%): 0.00 err/s 0.00 reconn/s: 0.00
[ 101s ] thds: 100 tps: 3501.85 qps: 99695.66 (r/w/o: 45473.02/47218.94/7003.70) lat (ms,95%): 257.95 err/s 14.00 reconn/s: 0.00
[ 102s ] thds: 100 tps: 6980.06 qps: 197777.73 (r/w/o: 90228.79/93588.82/13960.12) lat (ms,95%): 25.74 err/s 33.00 reconn/s: 0.00
[ 103s ] thds: 100 tps: 6745.15 qps: 196518.25 (r/w/o: 89717.94/93310.02/13490.29) lat (ms,95%): 26.68 err/s 46.00 reconn/s: 0.00
更新本身花了34秒.
在這種情況下, 祝工作負載停止了22秒. 基本上所有語句在這段時間都被暫停/阻塞了
With Streaming Replication
如何通過streaming replication改進這一點?
- 讓我們在執行更新語句的會話中啓用streaming replication
SET SESSION wsrep_trx_fragment_unit='rows';
SET SESSION wsrep_trx_fragment_size=1000;
基本上, 我們說集羣應該將大事務分割成多個塊, 每個塊1000行, 然後在這些較小的塊中進行復制.Other choices for unit beside ‘rows’ are ‘bytes’ or ‘statements’
And run the query:
mysql> update sbtest1 set k=k+1 limit 1000000;
Query OK, 1000000 rows affected (39.76 sec)
Rows matched: 1000000 Changed: 1000000 Warnings: 0
In sysbench-tpcc:
[ 81s ] thds: 100 tps: 6682.94 qps: 188552.70 (r/w/o: 85967.65/89221.16/13363.88) lat (ms,95%): 26.68 err/s 32.98 reconn/s: 0.00
[ 82s ] thds: 100 tps: 6700.92 qps: 192216.77 (r/w/o: 87715.23/91103.70/13397.84) lat (ms,95%): 27.17 err/s 27.01 reconn/s: 0.00
[ 83s ] thds: 100 tps: 3835.05 qps: 108387.43 (r/w/o: 49408.65/51302.68/7676.10) lat (ms,95%): 82.96 err/s 15.00 reconn/s: 0.00
[ 84s ] thds: 100 tps: 2210.13 qps: 63161.58 (r/w/o: 28852.64/29888.70/4420.25) lat (ms,95%): 95.81 err/s 9.00 reconn/s: 0.00
[ 85s ] thds: 100 tps: 2558.00 qps: 72592.08 (r/w/o: 33093.04/34383.04/5116.01) lat (ms,95%): 87.56 err/s 9.00 reconn/s: 0.00
[ 86s ] thds: 100 tps: 2617.99 qps: 75127.81 (r/w/o: 34299.91/35591.91/5235.99) lat (ms,95%): 78.60 err/s 9.00 reconn/s: 0.00
[ 87s ] thds: 100 tps: 2887.75 qps: 81760.97 (r/w/o: 37312.79/38672.68/5775.50) lat (ms,95%): 73.13 err/s 15.00 reconn/s: 0.00
[ 88s ] thds: 100 tps: 3024.00 qps: 84461.96 (r/w/o: 38606.98/39806.98/6048.00) lat (ms,95%): 69.29 err/s 15.00 reconn/s: 0.00
[ 89s ] thds: 100 tps: 3119.27 qps: 91128.99 (r/w/o: 41566.65/43323.80/6238.55) lat (ms,95%): 63.32 err/s 9.00 reconn/s: 0.00
[ 90s ] thds: 100 tps: 3385.74 qps: 98314.42 (r/w/o: 44883.54/46659.40/6771.48) lat (ms,95%): 56.84 err/s 14.00 reconn/s: 0.00
[ 91s ] thds: 100 tps: 3641.08 qps: 103916.20 (r/w/o: 47422.00/49212.04/7282.15) lat (ms,95%): 54.83 err/s 21.00 reconn/s: 0.00
[ 92s ] thds: 100 tps: 3850.12 qps: 106013.43 (r/w/o: 48296.56/50021.62/7695.25) lat (ms,95%): 57.87 err/s 23.00 reconn/s: 0.00
[ 93s ] thds: 100 tps: 3828.07 qps: 111682.90 (r/w/o: 51005.87/53015.90/7661.13) lat (ms,95%): 54.83 err/s 22.00 reconn/s: 0.00
[ 94s ] thds: 100 tps: 4358.95 qps: 122173.63 (r/w/o: 55746.37/57709.35/8717.90) lat (ms,95%): 42.61 err/s 14.00 reconn/s: 0.00
[ 95s ] thds: 100 tps: 4367.09 qps: 123297.63 (r/w/o: 56193.20/58370.24/8734.19) lat (ms,95%): 44.98 err/s 16.00 reconn/s: 0.00
[ 96s ] thds: 100 tps: 4272.92 qps: 118822.67 (r/w/o: 54076.94/56201.90/8543.83) lat (ms,95%): 46.63 err/s 24.00 reconn/s: 0.00
[ 97s ] thds: 100 tps: 4697.88 qps: 133071.68 (r/w/o: 60676.49/62997.43/9397.77) lat (ms,95%): 38.25 err/s 17.00 reconn/s: 0.00
[ 98s ] thds: 100 tps: 4742.21 qps: 135167.87 (r/w/o: 61693.68/63989.78/9484.41) lat (ms,95%): 37.56 err/s 21.00 reconn/s: 0.00
[ 99s ] thds: 100 tps: 4949.89 qps: 139343.00 (r/w/o: 63616.63/65826.58/9899.79) lat (ms,95%): 36.24 err/s 21.00 reconn/s: 0.00
[ 100s ] thds: 100 tps: 4766.10 qps: 139554.99 (r/w/o: 63695.37/66327.42/9532.20) lat (ms,95%): 36.89 err/s 18.00 reconn/s: 0.00
[ 101s ] thds: 100 tps: 5069.91 qps: 143318.44 (r/w/o: 65310.83/67867.79/10139.82) lat (ms,95%): 35.59 err/s 13.00 reconn/s: 0.00
[ 102s ] thds: 100 tps: 4947.06 qps: 140053.63 (r/w/o: 63820.74/66338.77/9894.12) lat (ms,95%): 36.24 err/s 23.00 reconn/s: 0.00
[ 103s ] thds: 100 tps: 5045.00 qps: 145397.93 (r/w/o: 66328.97/68978.97/10090.00) lat (ms,95%): 34.33 err/s 18.00 reconn/s: 0.00
[ 104s ] thds: 100 tps: 5139.02 qps: 141954.54 (r/w/o: 64723.25/66953.25/10278.04) lat (ms,95%): 36.24 err/s 28.00 reconn/s: 0.00
[ 105s ] thds: 100 tps: 5214.90 qps: 147582.10 (r/w/o: 67371.68/69780.63/10429.80) lat (ms,95%): 34.33 err/s 25.00 reconn/s: 0.00
[ 106s ] thds: 100 tps: 4924.08 qps: 139603.33 (r/w/o: 63673.06/66082.10/9848.16) lat (ms,95%): 36.24 err/s 23.00 reconn/s: 0.00
[ 107s ] thds: 100 tps: 5202.97 qps: 147199.09 (r/w/o: 67176.58/69616.57/10405.94) lat (ms,95%): 34.33 err/s 30.00 reconn/s: 0.00
[ 108s ] thds: 100 tps: 5219.91 qps: 147677.47 (r/w/o: 67416.84/69820.80/10439.82) lat (ms,95%): 33.72 err/s 28.00 reconn/s: 0.00
[ 109s ] thds: 100 tps: 5018.99 qps: 143211.61 (r/w/o: 65365.82/67808.81/10036.97) lat (ms,95%): 36.24 err/s 23.00 reconn/s: 0.00
[ 110s ] thds: 100 tps: 5070.16 qps: 142049.54 (r/w/o: 64817.07/67091.15/10141.32) lat (ms,95%): 34.95 err/s 17.00 reconn/s: 0.00
[ 111s ] thds: 100 tps: 4954.87 qps: 141476.26 (r/w/o: 64529.29/67037.23/9909.74) lat (ms,95%): 35.59 err/s 25.00 reconn/s: 0.00
[ 112s ] thds: 100 tps: 4827.12 qps: 140426.46 (r/w/o: 64103.58/66668.64/9654.24) lat (ms,95%): 35.59 err/s 19.00 reconn/s: 0.00
[ 113s ] thds: 100 tps: 5027.00 qps: 145229.08 (r/w/o: 66179.04/68996.04/10054.01) lat (ms,95%): 34.33 err/s 26.00 reconn/s: 0.00
[ 114s ] thds: 100 tps: 5099.87 qps: 144585.36 (r/w/o: 65976.34/68409.28/10199.74) lat (ms,95%): 34.33 err/s 26.00 reconn/s: 0.00
[ 115s ] thds: 100 tps: 5010.11 qps: 143316.08 (r/w/o: 65356.40/67939.46/10020.22) lat (ms,95%): 34.95 err/s 26.00 reconn/s: 0.00
[ 116s ] thds: 100 tps: 5056.00 qps: 143686.98 (r/w/o: 65621.99/67952.99/10112.00) lat (ms,95%): 34.95 err/s 31.00 reconn/s: 0.00
[ 117s ] thds: 100 tps: 4908.95 qps: 141669.49 (r/w/o: 64653.31/67198.28/9817.90) lat (ms,95%): 36.24 err/s 21.00 reconn/s: 0.00
[ 118s ] thds: 100 tps: 5039.07 qps: 142667.01 (r/w/o: 65056.92/67531.95/10078.14) lat (ms,95%): 34.33 err/s 24.00 reconn/s: 0.00
[ 119s ] thds: 100 tps: 5076.89 qps: 143205.79 (r/w/o: 65195.54/67856.48/10153.77) lat (ms,95%): 35.59 err/s 18.00 reconn/s: 0.00
[ 120s ] thds: 100 tps: 4909.09 qps: 137380.48 (r/w/o: 62539.13/65024.17/9817.18) lat (ms,95%): 34.95 err/s 13.00 reconn/s: 0.00
[ 121s ] thds: 100 tps: 5024.93 qps: 144610.91 (r/w/o: 66027.05/68533.01/10050.85) lat (ms,95%): 35.59 err/s 23.00 reconn/s: 0.00
[ 122s ] thds: 100 tps: 4874.10 qps: 138066.96 (r/w/o: 62942.35/65376.40/9748.21) lat (ms,95%): 35.59 err/s 16.00 reconn/s: 0.00
[ 123s ] thds: 100 tps: 6745.83 qps: 187288.34 (r/w/o: 85354.88/88441.80/13491.66) lat (ms,95%): 28.67 err/s 27.00 reconn/s: 0.00
[ 124s ] thds: 100 tps: 6132.03 qps: 172854.73 (r/w/o: 78867.33/81723.34/12264.05) lat (ms,95%): 29.19 err/s 18.00 reconn/s: 0.00
[ 125s ] thds: 100 tps: 6114.99 qps: 175777.68 (r/w/o: 80098.85/83448.85/12229.98) lat (ms,95%): 30.26 err/s 39.00 reconn/s: 0.00
[ 126s ] thds: 100 tps: 6206.87 qps: 179830.22 (r/w/o: 82043.28/85374.21/12412.74) lat (ms,95%): 29.72 err/s 29.00 reconn/s: 0.00
[ 127s ] thds: 100 tps: 6441.25 qps: 181759.03 (r/w/o: 82799.20/86076.33/12883.50) lat (ms,95%): 28.67 err/s 28.00 reconn/s: 0.00
[ 128s ] thds: 100 tps: 5925.87 qps: 169978.30 (r/w/o: 77565.31/80561.24/11851.74) lat (ms,95%): 30.81 err/s 32.00 reconn/s: 0.00
[ 129s ] thds: 100 tps: 6614.92 qps: 186834.71 (r/w/o: 85216.96/88388.92/13228.84) lat (ms,95%): 27.66 err/s 24.00 reconn/s: 0.00
so 這裏發生了什麼:
更新查詢花了更長的時間(39秒而不是34秒).主要工作負載也受到了一些影響(從6700 tps下降到最壞時期的2210 tps), 但並沒有完全停止, 這是一個巨大的改進.
爲什麼我們不應該默認爲所有事務啓用streaming replication?原因是它可能會對常規的小事務產生負面影響, 所以建議只對大型或長時間運行的事務使用streaming replication.