我有以下查找表:的MySQL的MyISAM磁盘绑定的规模问题/驱动器高速缓存
CREATE TABLE `widgetuser` (
`widgetuserid` char(40) NOT NULL,
`userid` int(10) unsigned NOT NULL,
`created_at` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00',
PRIMARY KEY (`widgetuserid`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8 DELAY_KEY_WRITE=1;
我有相同结构的widgetuser_tmp表,但没有钥匙,我填写widgetuser表这个数据( 4mio行):
mysql> insert into widgetuser select * from widgetuser_tmp limit 0,4000000;flush tables;
Query OK, 4000000 rows affected (33.14 sec)
Records: 4000000 Duplicates: 0 Warnings: 0
Query OK, 0 rows affected (0.91 sec)
虽然是写作,它会直接到RAID-1与15MB /秒,盘UTIL < 50%,我们看不出有任何读,因为我充满了源表中的磁盘缓存:
Device: rrqm/s wrqm/s r/s w/s rMB/s wMB/s avgrq-sz avgqu-sz await svctm %util
sda 0.00 3839.20 0.00 52.40 0.00 15.20 594.20 12.46 237.75 5.57 29.20
sdb 0.00 3839.00 0.00 52.60 0.00 15.20 591.94 14.50 275.59 7.19 37.80
我将下一1个百万行,这是所有罚款和WMB/s的冲洗之后回到0:
mysql> insert into widgetuser select * from widgetuser_tmp limit 4000000,1000000;flush tables;
Query OK, 1000000 rows affected (10.18 sec)
Records: 1000000 Duplicates: 0 Warnings: 0
Query OK, 0 rows affected (0.87 sec)
mysql> insert into widgetuser select * from widgetuser_tmp limit 5000000,1000000;flush tables;
Query OK, 1000000 rows affected (10.21 sec)
Records: 1000000 Duplicates: 0 Warnings: 0
Query OK, 0 rows affected (1.02 sec)
mysql> insert into widgetuser select * from widgetuser_tmp limit 6000000,1000000;flush tables;
Query OK, 1000000 rows affected (10.67 sec)
Records: 1000000 Duplicates: 0 Warnings: 0
Query OK, 0 rows affected (1.17 sec)
但是,当我做7mio批次,结果看起来还是一样,但在iostat -mdx sda sdb 5
突然,我们有100%的util 30秒:
mysql> insert into widgetuser select * from widgetuser_tmp limit 7000000,1000000;flush tables;
Query OK, 1000000 rows affected (10.73 sec)
Records: 1000000 Duplicates: 0 Warnings: 0
Query OK, 0 rows affected (1.21 sec)
Device: rrqm/s wrqm/s r/s w/s rMB/s wMB/s avgrq-sz avgqu-sz await svctm %util
sda 0.00 88.60 0.00 295.60 0.00 1.52 10.53 130.60 435.93 3.38 100.00
sdb 0.00 89.20 0.00 300.80 0.00 1.57 10.68 143.99 483.97 3.32 100.00
的数据文件刷新后不感动:
-rw-rw---- 1 mysql mysql 1032000000 2009-10-30 12:10 widgetuser.MYD
-rw-rw---- 1 mysql mysql 522777600 2009-10-30 12:11 widgetuser.MYI
而且也表状态接缝正常:
+----------------+--------+---------+------------+----------+----------------+-------------+-------------------+--------------+-----------+----------------+---------------------+---------------------+------------+-----------------+----------+-------------------+---------+
| Name | Engine | Version | Row_format | Rows | Avg_row_length | Data_length | Max_data_length | Index_length | Data_free | Auto_increment | Create_time | Update_time | Check_time | Collation | Checksum | Create_options | Comment |
+----------------+--------+---------+------------+----------+----------------+-------------+-------------------+--------------+-----------+----------------+---------------------+---------------------+------------+-----------------+----------+-------------------+---------+
| widgetuser | MyISAM | 10 | Fixed | 8000000 | 129 | 1032000000 | 36310271995674623 | 522777600 | 0 | NULL | 2009-10-30 11:59:41 | 2009-10-30 12:10:59 | NULL | utf8_general_ci | NULL | delay_key_write=1 | |
+----------------+--------+---------+------------+----------+----------------+-------------+-------------------+--------------+-----------+----------------+---------------------+---------------------+------------+-----------------+----------+-------------------+---------+
当我继续(因为我们有100%的驱动器的使用率),它获得的恶化速度非常快:
mysql> insert into widgetuser select * from widgetuser_tmp limit 9000000,1000000;flush tables;
Query OK, 1000000 rows affected (31.93 sec)
Records: 1000000 Duplicates: 0 Warnings: 0
Query OK, 0 rows affected (2.34 sec)
mysql> insert into widgetuser select * from widgetuser_tmp limit 10000000,1000000;flush tables;
Query OK, 1000000 rows affected (2 min 39.72 sec)
Records: 1000000 Duplicates: 0 Warnings: 0
Query OK, 0 rows affected (7.82 sec)
主键检查看看新条目是否是唯一的。只要密钥不适合内存(key_buffer_size = 512MB =大约8Mio条目),它就需要从驱动器(-cache)中提取缺失的关键部件以检查它。因此,我们应该看到更多的读取和更慢的插入时间 - 由于密钥缓存在磁盘缓存中,因此我们看不到较慢的读取。但我的问题:谁突然写这么多,在哪里,为什么,我该如何解决这个问题?任何想法表示赞赏!
Futher的想法和见解:
-
因为1MB/s的随机写入
- 遵循成品声明,独特的验证已经通过
- 它是一个软件RAID-1 AHCI上,磁盘93%的游离,并且能够为约80wMB/s的
- 机器已经8GB RAM,5GB缓存,600MB采取的MySQL,1,7GB自由
- 的MySQL 5.1.31-1ubuntu2日志
- 的DELAY_KEY_WRITE不改变这种行为
- myisam_sort_buffer_size = 2 GB(这里没有使用,但是?)
- 的key_buffer_size = 512 MB
- bin_log熄灭
- Linux的2.6.28-15服务器#52,Ubuntu的SMP星期三9月9日11:34:09 UTC 2009 x86_64 GNU/Linux
谢谢,我将检查block_size - 目前它是1024. 是索引不适合在关键缓冲区中,但我不明白为什么这需要额外写入_after_插入提交。读我会明白,插入速度较慢,但我不明白随机写入,你可以看到第二个iostat转储! 谢谢! – smint 2009-10-30 14:12:34