Mysql
MySQL需要很長時間才能啟動
我試圖理解為什麼 mysql 需要 2000 萬才能啟動。
我正在執行 5.7.17-13-log，即使啟動了每個表的文件，我也有一個大的 ibdata1 文件（20GB）。這是它的內容：
# innochecksum -S /data/mysql/ibdata1 File::/data/mysql/ibdata1 ================PAGE TYPE SUMMARY============== #PAGE_COUNT PAGE_TYPE =============================================== 781526 Index page 1031230 Undo log page 11836 Inode page 25060 Insert buffer free list page 22645 Freshly allocated page 114 Insert buffer bitmap 107 System page 1 Transaction system page 2 File Space Header 116 Extent descriptor page 3 BLOB page 0 Compressed BLOB page 0 Other type of page ===============================================這是我在錯誤日誌中看到的內容：
2017-06-05T19:08:31.307808Z 0 [Note] InnoDB: Highest supported file format is Barracuda. 2017-06-05T19:08:31.719378Z 0 [Note] InnoDB: Created parallel doublewrite buffer at /data/mysql/xb_doublewrite, size 31457280 bytes 2017-06-05T19:29:09.747406Z 0 [Note] InnoDB: Creating shared tablespace for temporary tables 2017-06-05T19:29:09.747507Z 0 [Note] InnoDB: Setting file './ibtmp1' size to 12 MB. Physically writing the file full; Please wait ... 2017-06-05T19:29:09.763021Z 0 [Note] InnoDB: File './ibtmp1' size is now 12 MB. 2017-06-05T19:29:09.869445Z 0 [Note] InnoDB: 96 redo rollback segment(s) found. 96 redo rollback segment(s) are active. 2017-06-05T19:29:09.869470Z 0 [Note] InnoDB: 32 non-redo rollback segment(s) are active. 2017-06-05T19:29:09.869574Z 0 [Note] InnoDB: page_cleaner: 1000ms intended loop took 1238576ms. The settings might not be optimal. (flushed=0, during the time.)我看到有人提到頁面清潔器後來花了 2000 萬，在啟動時聽起來很奇怪！
這是 mysqld 上的 sysdig 輸出，表明它一直在讀取 ibdata1：
11706 13:01:38.019123953 0 mysqld (94026) > pread fd=4(<f>/data/mysql/ibdata1) size=16384 pos=9304113152 11707 13:01:38.019163204 0 mysqld (94026) > switch next=0 pgft_maj=1 pgft_min=4116243 vm_size=45320516 vm_rss=14609036 vm_swap=0 11709 13:01:38.019292874 0 mysqld (94026) < pread res=16384 data=.......F...E..._...n....E..............6?a..=..h................................ 11712 13:01:38.019337538 0 mysqld (94026) > pread fd=4(<f>/data/mysql/ibdata1) size=16384 pos=9232695296 11713 13:01:38.019355435 0 mysqld (94026) > switch next=0 pgft_maj=1 pgft_min=4116247 vm_size=45320516 vm_rss=14609036 vm_swap=0 11715 13:01:38.019399597 0 mysqld (94026) < pread res=16384 data=.......?...9...G...n....E..............5?1.j.................................... 11718 13:01:38.040605854 0 mysqld (94026) > pread fd=4(<f>/data/mysql/ibdata1) size=16384 pos=9304522752 11719 13:01:38.040644306 0 mysqld (94026) > switch next=0 pgft_maj=1 pgft_min=4116438 vm_size=45320516 vm_rss=14609560 vm_swap=0 11721 13:01:38.040774631 0 mysqld (94026) < pread res=16384 data=69....._...F...n...n....E..............*?A...u. .....w.......................... 11872 13:01:38.062582012 0 mysqld (94026) > pread fd=4(<f>/data/mysql/ibdata1) size=16384 pos=9232826368 11873 13:01:38.062633600 0 mysqld (94026) > switch next=0 pgft_maj=1 pgft_min=4116541 vm_size=45320516 vm_rss=14610084 vm_swap=0 11875 13:01:38.062748273 0 mysqld (94026) < pread res=16384 data=.te=...G...?...O...n.(.gE..............X?8.i.R.......f.c........................更新 1
innodb-flush-method = O_DIRECT innodb-log-files-in-group = 2 innodb-log-file-size = 512M innodb-flush-log-at-trx-commit = 1 innodb-file-per-table = 1 innodb-buffer-pool-size = 32G innodb_log_buffer_size = 128M innodb_buffer_pool_instances = 8 innodb_max_dirty_pages_pct = 5 innodb_io_capacity = 2000 innodb_buffer_pool_dump_at_shutdown = 1 innodb_buffer_pool_load_at_startup = 1有任何想法嗎？
謝謝，
原來，mysql 會掃描所有 undo 以查找未送出的事務。
由於我在 ibdata 中有一個非常大的撤消空間，我轉而使用撤消表空間。設置撤消截斷選項使我的撤消表空間非常小。
現在我的數據庫在 2-3 百萬頂部打開！謝謝，