TL;DR
インストール
- releases にrpmパッケージもあるので
yumでサクっと入れた。- コマンド1個だけが入っているとてもシンプルなパッケージ…
$ sudo yum install -y https://github.com/github/gh-ost/releases/download/v1.0.48/gh-ost-1.0.48-1.x86_64.rpm
$ rpm -ql gh-ost
/usr/bin/gh-ost
テスト
- ドキュメント を一切合切読まずに試してみる。
- MySQL::Sandbox と
mysqlslapでテキトーなテーブル定義にテキトーなクエリーを流させておく。general_logはオンにしてみた。
$ make_replication_sandbox 5.7.25
$ cd ~/sandboxes/rsandbox_5_7_25/
$ ./m
master [localhost] {msandbox} ((none)) > SET GLOBAL general_log= 1;
Query OK, 0 rows affected (0.00 sec)
$ master/my sqlslap --auto-generate-sql --auto-generate-sql-execute-number=100000
- 何もオプションを指定せずに打ってみた（何故）
$ gh-ost
2019-02-25 17:18:10 FATAL --database must be provided and database name must not be empty
--databaseが要ることは分かった。
$ gh-ost --database=mysqlslap
2019-02-25 17:18:45 FATAL --table must be provided and table name must not be empty
--tableも要ることは分かった。
$ gh-ost --database=mysqlslap --table=t1
2019-02-25 17:19:10 FATAL --alter must be provided and statement must not be empty
--alterも要ることはわかった。これは pt-online-schema-change と一緒で、ALTERオペレーションの部分だけを書けばいいのかしらん。
$ gh-ost --database=mysqlslap --table=t1 --alter="ADD KEY (intcol1)"
2019-02-25 17:20:17 FATAL dial tcp 127.0.0.1:3306: connect: connection refused
- ここで初めて接続エラーになった。たぶん
--hostと--portと--userと--passwordでイケるだろ、と思う。
$ gh-ost --database=mysqlslap --table=t1 --alter="ADD KEY (intcol1)" --host=127.0.0.1 --port=21800 --user=msandbox --password=msandbox
2019-02-25 17:21:14 FATAL No PRIMARY nor UNIQUE key found in table! Bailing out
- テーブルに
PRIMARY KEYまたはUNIQUE KEYがないと適用できない。 - 確かに
binlog_format= ROWなバイナリログを食わせて、ALTER適用済のテンポラリーテーブル（gh-ost的には「ゴーストテーブル」というらしい）を作るにはないと具合が悪い。
2019-02-25T08:23:03.835939Z 11 Connect msandbox@localhost on mysqlslap using TCP/IP
..
2019-02-25T08:23:03.838067Z 11 Query show /* gh-ost */ grants for current_user()
2019-02-25T08:23:03.838364Z 11 Query select @@global.log_bin, @@global.binlog_format
2019-02-25T08:23:03.838580Z 11 Query select @@global.binlog_row_image
2019-02-25T08:23:03.839329Z 12 Connect msandbox@localhost on information_schema using TCP/IP
2019-02-25T08:23:03.839500Z 12 Query SELECT @@max_allowed_packet
2019-02-25T08:23:03.839623Z 12 Query SET autocommit=true
2019-02-25T08:23:03.839737Z 12 Query SET NAMES utf8mb4
2019-02-25T08:23:03.839966Z 12 Query show slave status
2019-02-25T08:23:03.840312Z 12 Quit
2019-02-25T08:23:03.840475Z 11 Query show /* gh-ost */ table status from `mysqlslap` like 't1'
2019-02-25T08:23:03.841162Z 11 Query SELECT
..
FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE
WHERE
REFERENCED_TABLE_NAME IS NOT NULL
AND ((TABLE_SCHEMA='mysqlslap' AND TABLE_NAME='t1')
OR (REFERENCED_TABLE_SCHEMA='mysqlslap' AND REFERENCED_TABLE_NAME='t1')
)
2019-02-25T08:23:03.851679Z 11 Query SELECT
..
FROM INFORMATION_SCHEMA.COLUMNS INNER JOIN (
SELECT
..
FROM INFORMATION_SCHEMA.STATISTICS
WHERE
NON_UNIQUE=0
AND TABLE_SCHEMA = 'mysqlslap'
AND TABLE_NAME = 't1'
GROUP BY TABLE_SCHEMA, TABLE_NAME, INDEX_NAME
) AS UNIQUES
ON (
COLUMNS.COLUMN_NAME = UNIQUES.FIRST_COLUMN_NAME
)
WHERE
COLUMNS.TABLE_SCHEMA = 'mysqlslap'
AND COLUMNS.TABLE_NAME = 't1'
ORDER BY
..
2019-02-25T08:23:03.853012Z 11 Quit
- 外部キー制約がついてるとこの辺で判定されそうな感じ。
mysqlslapがPRIMARY KEYを作るようにオプションを追加してやり直し。
$ master/my sqlslap --auto-generate-sql --auto-generate-sql-execute-number=100000 --auto-generate-sql-guid-primary
$ gh-ost --database=mysqlslap --table=t1 --alter="ADD KEY (intcol1)" --host=127.0.0.1 --port=21800 --user=msandbox --password=msandbox
2019-02-25 17:28:29 FATAL It seems like this migration attempt to run directly on master. Preferably it would be executed on a replica (and this reduces load from the master). To proceed please provide --allow-on-master. Inspector config=127.0.0.1:21800, user=msandbox, usingTLS=false, applier config=127.0.0.1:21800, user=msandbox, usingTLS=false
- 直接マスターに接続するなら
--allow-on-master使えってことらしい。 - バイナリーログはマスターから食ってもスレーブから食っても一緒なんでは？ と思うけれど チートシート を見る感じ、デフォルトはスレーブでバイナリーログを食ってマスターにINSERT、のようだ。
$ gh-ost --database=mysqlslap --table=t1 --alter="ADD KEY (intcol1)" --host=127.0.0.1 --port=21800 --user=msandbox --password=msandbox --allow-on-master
[2019/02/25 17:32:48] [info] binlogsyncer.go:133 create BinlogSyncer with config {99999 mysql 127.0.0.1 21800 msandbox false false <nil> false UTC true 0 0s 0s 0 false}
[2019/02/25 17:32:48] [info] binlogsyncer.go:354 begin to sync binlog from position (mysql-bin.000001, 34947374)
[2019/02/25 17:32:48] [info] binlogsyncer.go:203 register slave for master server 127.0.0.1:21800
[2019/02/25 17:32:48] [info] binlogsyncer.go:723 rotate to (mysql-bin.000001, 34947374)
# Migrating `mysqlslap`.`t1`; Ghost table is `mysqlslap`.`_t1_gho`
# Migrating 163-44-175-117:21800; inspecting 163-44-175-117:21800; executing on 163-44-175-117
# Migration started at Mon Feb 25 17:32:47 +0900 2019
# chunk-size: 1000; max-lag-millis: 1500ms; dml-batch-size: 10; max-load: ; critical-load: ; nice-ratio: 0.000000
# throttle-additional-flag-file: /tmp/gh-ost.throttle
# Serving on unix socket: /tmp/gh-ost.mysqlslap.t1.sock
# Migrating `mysqlslap`.`t1`; Ghost table is `mysqlslap`.`_t1_gho`
# Migrating 163-44-175-117:21800; inspecting 163-44-175-117:21800; executing on 163-44-175-117
# Migration started at Mon Feb 25 17:32:47 +0900 2019
# chunk-size: 1000; max-lag-millis: 1500ms; dml-batch-size: 10; max-load: ; critical-load: ; nice-ratio: 0.000000
# throttle-additional-flag-file: /tmp/gh-ost.throttle
# Serving on unix socket: /tmp/gh-ost.mysqlslap.t1.sock
Copy: 0/6772 0.0%; Applied: 0; Backlog: 1/1000; Time: 0s(total), 0s(copy); streamer: mysql-bin.000001:34958571; State: migrating; ETA: N/A
Copy: 0/0 100.0%; Applied: 0; Backlog: 1/1000; Time: 0s(total), 0s(copy); streamer: mysql-bin.000001:34958571; State: migrating; ETA: due
CREATE TABLE `_t1_gho` (
`id` varchar(36) NOT NULL,
`intcol1` int(32) DEFAULT NULL,
`charcol1` varchar(128) DEFAULT NULL,
PRIMARY KEY (`id`),
KEY `intcol1` (`intcol1`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1
[2019/02/25 17:32:48] [info] binlogsyncer.go:164 syncer is closing...
[2019/02/25 17:32:48] [error] binlogstreamer.go:77 close sync with err: sync is been closing...
[2019/02/25 17:32:48] [info] binlogsyncer.go:179 syncer is closed
# Done
master [localhost] {msandbox} (mysqlslap) > show create table t1\G
*************************** 1. row ***************************
Table: t1
Create Table: CREATE TABLE `t1` (
`id` varchar(36) NOT NULL,
`intcol1` int(32) DEFAULT NULL,
`charcol1` varchar(128) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1
1 row in set (0.00 sec)
- 動いたっぽい。
- この時点では
dry-runで、実行はされていない（って出力してくれてもいいのに）- ちょくちょく
pt-online-schema-changeと動きが同じで嬉しい。
- ちょくちょく
- この時点では
SHOW PROCESSLISTやSHOW SLAVE HOSTSなどマスターからスレーブを探せるようなSQLは叩いていない。 # chunk-size: 1000; max-lag-millis: 1500ms; dml-batch-size: 10; max-load: ; critical-load: ; nice-ratio: 0.000000あたりは、--helpを見た感じ負荷に合わせてよしなに指定するのであろう。- ちなみにこの時点で
binlog_format <> ROWの場合はエラーが出る（FATAL You must be using ROW binlog format. I can switch it for you, provided --switch-to-rbr and that 127.0.0.1:21800 doesn't have replicas）
$ gh-ost --database=mysqlslap --table=t1 --alter="ADD KEY (intcol1)" --host=127.0.0.1 --port=21800 --user=msandbox --password=msandbox --allow-on-master --execute
[2019/02/25 17:38:56] [info] binlogsyncer.go:133 create BinlogSyncer with config {99999 mysql 127.0.0.1 21800 msandbox false false <nil> false UTC true 0 0s 0s 0 false}
[2019/02/25 17:38:56] [info] binlogsyncer.go:354 begin to sync binlog from position (mysql-bin.000001, 80752389)
[2019/02/25 17:38:56] [info] binlogsyncer.go:203 register slave for master server 127.0.0.1:21800
[2019/02/25 17:38:56] [info] binlogsyncer.go:723 rotate to (mysql-bin.000001, 80752389)
# Migrating `mysqlslap`.`t1`; Ghost table is `mysqlslap`.`_t1_gho`
# Migrating 163-44-175-117:21800; inspecting 163-44-175-117:21800; executing on 163-44-175-117
# Migration started at Mon Feb 25 17:38:56 +0900 2019
# chunk-size: 1000; max-lag-millis: 1500ms; dml-batch-size: 10; max-load: ; critical-load: ; nice-ratio: 0.000000
# throttle-additional-flag-file: /tmp/gh-ost.throttle
# Serving on unix socket: /tmp/gh-ost.mysqlslap.t1.sock
Copy: 0/3346 0.0%; Applied: 0; Backlog: 1/1000; Time: 0s(total), 0s(copy); streamer: mysql-bin.000001:80762720; State: migrating; ETA: N/A
Copy: 2000/3346 59.8%; Applied: 179; Backlog: 0/1000; Time: 1s(total), 1s(copy); streamer: mysql-bin.000001:81254459; State: migrating; ETA: 0s
Copy: 3365/3346 100.6%; Applied: 359; Backlog: 1/1000; Time: 2s(total), 2s(copy); streamer: mysql-bin.000001:81644106; State: migrating; ETA: due
Copy: 3365/3365 100.0%; Applied: 424; Backlog: 0/1000; Time: 2s(total), 2s(copy); streamer: mysql-bin.000001:81700141; State: migrating; ETA: due
Copy: 3365/3365 100.0%; Applied: 426; Backlog: 10/1000; Time: 3s(total), 2s(copy); streamer: mysql-bin.000001:81709653; State: migrating; ETA: due
# Migrating `mysqlslap`.`t1`; Ghost table is `mysqlslap`.`_t1_gho`
# Migrating 163-44-175-117:21800; inspecting 163-44-175-117:21800; executing on 163-44-175-117
# Migration started at Mon Feb 25 17:38:56 +0900 2019
# chunk-size: 1000; max-lag-millis: 1500ms; dml-batch-size: 10; max-load: ; critical-load: ; nice-ratio: 0.000000
# throttle-additional-flag-file: /tmp/gh-ost.throttle
# Serving on unix socket: /tmp/gh-ost.mysqlslap.t1.sock
Copy: 3365/3365 100.0%; Applied: 435; Backlog: 0/1000; Time: 3s(total), 2s(copy); streamer: mysql-bin.000001:81714074; State: migrating; ETA: due
[2019/02/25 17:39:00] [info] binlogsyncer.go:164 syncer is closing...
[2019/02/25 17:39:00] [error] binlogstreamer.go:77 close sync with err: sync is been closing...
[2019/02/25 17:39:00] [info] binlogsyncer.go:179 syncer is closed
# Done
- 流れ終わりは、した。
master [localhost] {msandbox} (mysqlslap) > SHOW CREATE TABLE t1\G
*************************** 1. row ***************************
Table: t1
Create Table: CREATE TABLE `t1` (
`id` varchar(36) NOT NULL,
`intcol1` int(32) DEFAULT NULL,
`charcol1` varchar(128) DEFAULT NULL,
PRIMARY KEY (`id`),
KEY `intcol1` (`intcol1`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1
1 row in set (0.00 sec)
slave1 [localhost] {msandbox} (mysqlslap) > SHOW CREATE TABLE t1\G
*************************** 1. row ***************************
Table: t1
Create Table: CREATE TABLE `t1` (
`id` varchar(36) NOT NULL,
`intcol1` int(32) DEFAULT NULL,
`charcol1` varchar(128) DEFAULT NULL,
PRIMARY KEY (`id`),
KEY `intcol1` (`intcol1`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1
1 row in set (0.01 sec)
$ less ~/sandboxes/rsandbox_5_7_25/node1/data/163-44-175-117.log
..
- マスターでもスレーブでもインデックスが足されているのはいいけれど、どうもgeneral_logを見る限り
Seconds_Behind_Masterを見に来ている気配はない。。- これはスレーブからバイナリーログを受け取る設定にしている時に、その接続先で
SHOW SLAVE STATUS叩いたり--throttle-control-replicasを指定した時にだけその先で叩いてくれるのかしらん。謎。
- これはスレーブからバイナリーログを受け取る設定にしている時に、その接続先で
$ cat -v ~/sandboxes/rsandbox_5_7_25/master/data/163-44-175-117.log | grep "gh-ost"
..
2019-02-25T08:38:56.880696Z 41 Query show /* gh-ost */ grants for current_user()
2019-02-25T08:38:56.882845Z 41 Query show /* gh-ost */ table status from `mysqlslap` like 't1'
2019-02-25T08:38:56.902645Z 41 Query explain select /* gh-ost */ * from `mysqlslap`.`t1` where 1=1
2019-02-25T08:38:56.907683Z 41 Query show /* gh-ost readCurrentBinlogCoordinates */ master status
2019-02-25T08:38:56.917044Z 41 Query show /* gh-ost */ table status from `mysqlslap` like '_t1_gho'
2019-02-25T08:38:56.917296Z 41 Query show /* gh-ost */ table status from `mysqlslap` like '_t1_del'
2019-02-25T08:38:56.917506Z 41 Query drop /* gh-ost */ table if exists `mysqlslap`.`_t1_ghc`
2019-02-25T08:38:56.920110Z 41 Query create /* gh-ost */ table `mysqlslap`.`_t1_ghc` (
2019-02-25T08:38:56.931295Z 41 Query create /* gh-ost */ table `mysqlslap`.`_t1_gho` like `mysqlslap`.`t1`
2019-02-25T08:38:56.946308Z 41 Query alter /* gh-ost */ table `mysqlslap`.`_t1_gho` ADD KEY (intcol1)
2019-02-25T08:38:56.959104Z 41 Query insert /* gh-ost */ into `mysqlslap`.`_t1_ghc`
2019-02-25T08:38:56.962483Z 41 Query insert /* gh-ost */ into `mysqlslap`.`_t1_ghc`
2019-02-25T08:38:56.965301Z 41 Query insert /* gh-ost */ into `mysqlslap`.`_t1_ghc`
2019-02-25T08:38:56.972091Z 41 Query select /* gh-ost `mysqlslap`.`t1` */ `id`
2019-02-25T08:38:56.972536Z 47 Query select /* gh-ost `mysqlslap`.`t1` */ `id`
2019-02-25T08:38:56.973362Z 47 Query insert /* gh-ost */ into `mysqlslap`.`_t1_ghc`
2019-02-25T08:38:56.973989Z 41 Query replace /* gh-ost `mysqlslap`.`_t1_gho` */ into
2019-02-25T08:38:56.977606Z 47 Query replace /* gh-ost `mysqlslap`.`_t1_gho` */ into
2019-02-25T08:38:56.982191Z 41 Query replace /* gh-ost `mysqlslap`.`_t1_gho` */ into
2019-02-25T08:38:56.986080Z 47 Query replace /* gh-ost `mysqlslap`.`_t1_gho` */ into
...
2019-02-25T08:38:59.213685Z 66 Query replace /* gh-ost `mysqlslap`.`_t1_gho` */ into
2019-02-25T08:38:59.221449Z 67 Query select /* gh-ost `mysqlslap`.`t1` iteration:4 */
2019-02-25T08:38:59.221871Z 66 Query select /* gh-ost `mysqlslap`.`t1` iteration:4 */ `id`
2019-02-25T08:38:59.222528Z 67 Query replace /* gh-ost `mysqlslap`.`_t1_gho` */ into
2019-02-25T08:38:59.222842Z 66 Query insert /* gh-ost */ into `mysqlslap`.`_t1_ghc`
2019-02-25T08:38:59.228316Z 67 Query replace /* gh-ost `mysqlslap`.`_t1_gho` */ into
2019-02-25T08:38:59.241504Z 66 Query select get_lock('gh-ost.66.lock', 0)
2019-02-25T08:38:59.242713Z 67 Query show /* gh-ost */ table status from `mysqlslap` like '_t1_del'
2019-02-25T08:38:59.246396Z 67 Query create /* gh-ost */ table `mysqlslap`.`_t1_del` (
2019-02-25T08:38:59.272465Z 69 Query insert /* gh-ost */ into `mysqlslap`.`_t1_ghc`
2019-02-25T08:38:59.272797Z 66 Query lock /* gh-ost */ tables `mysqlslap`.`t1` write, `mysqlslap`.`_t1_del` write
2019-02-25T08:38:59.276302Z 67 Query insert /* gh-ost */ into `mysqlslap`.`_t1_ghc`
2019-02-25T08:38:59.279341Z 69 Query insert /* gh-ost */ into `mysqlslap`.`_t1_ghc`
2019-02-25T08:38:59.371523Z 67 Query insert /* gh-ost */ into `mysqlslap`.`_t1_ghc`
2019-02-25T08:38:59.471494Z 69 Query insert /* gh-ost */ into `mysqlslap`.`_t1_ghc`
2019-02-25T08:38:59.571439Z 67 Query insert /* gh-ost */ into `mysqlslap`.`_t1_ghc`
2019-02-25T08:38:59.671521Z 69 Query insert /* gh-ost */ into `mysqlslap`.`_t1_ghc`
2019-02-25T08:38:59.771526Z 67 Query insert /* gh-ost */ into `mysqlslap`.`_t1_ghc`
2019-02-25T08:38:59.871520Z 69 Query insert /* gh-ost */ into `mysqlslap`.`_t1_ghc`
2019-02-25T08:38:59.971540Z 67 Query insert /* gh-ost */ into `mysqlslap`.`_t1_ghc`
2019-02-25T08:38:59.976502Z 69 Query insert /* gh-ost */ into `mysqlslap`.`_t1_ghc`
2019-02-25T08:39:00.071569Z 67 Query insert /* gh-ost */ into `mysqlslap`.`_t1_ghc`
2019-02-25T08:39:00.171486Z 69 Query insert /* gh-ost */ into `mysqlslap`.`_t1_ghc`
2019-02-25T08:39:00.251211Z 67 Query replace /* gh-ost `mysqlslap`.`_t1_gho` */ into
2019-02-25T08:39:00.251556Z 67 Query replace /* gh-ost `mysqlslap`.`_t1_gho` */ into
2019-02-25T08:39:00.251754Z 67 Query replace /* gh-ost `mysqlslap`.`_t1_gho` */ into
2019-02-25T08:39:00.251977Z 67 Query replace /* gh-ost `mysqlslap`.`_t1_gho` */ into
2019-02-25T08:39:00.252143Z 67 Query replace /* gh-ost `mysqlslap`.`_t1_gho` */ into
2019-02-25T08:39:00.252348Z 67 Query replace /* gh-ost `mysqlslap`.`_t1_gho` */ into
2019-02-25T08:39:00.252505Z 67 Query replace /* gh-ost `mysqlslap`.`_t1_gho` */ into
2019-02-25T08:39:00.252679Z 67 Query replace /* gh-ost `mysqlslap`.`_t1_gho` */ into
2019-02-25T08:39:00.252847Z 67 Query replace /* gh-ost `mysqlslap`.`_t1_gho` */ into
2019-02-25T08:39:00.264470Z 69 Query insert /* gh-ost */ into `mysqlslap`.`_t1_ghc`
2019-02-25T08:39:00.271783Z 67 Query insert /* gh-ost */ into `mysqlslap`.`_t1_ghc`
2019-02-25T08:39:00.285571Z 69 Query rename /* gh-ost */ table `mysqlslap`.`t1` to `mysqlslap`.`_t1_del`, `mysqlslap`.`_t1_gho` to `mysqlslap`.`t1`
2019-02-25T08:39:00.297535Z 70 Query select is_used_lock('gh-ost.66.lock')
2019-02-25T08:39:00.297781Z 66 Query drop /* gh-ost */ table if exists `mysqlslap`.`_t1_del`
2019-02-25T08:39:00.361910Z 70 Query show /* gh-ost */ table status from `mysqlslap` like '_t1_del'
2019-02-25T08:39:00.374467Z 67 Query insert /* gh-ost */ into `mysqlslap`.`_t1_ghc`
2019-02-25T08:39:00.383095Z 69 Query drop /* gh-ost */ table if exists `mysqlslap`.`_t1_ghc`
- なんか
*_ghcテーブルと*_ghoテーブルを使ってる？
..
2019-02-25T08:39:00.264470Z 69 Query insert /* gh-ost */ into `mysqlslap`.`_t1_ghc`
(id, hint, value)
values
(NULLIF(0, 0), 'copy iteration 4 at 1551083940', 'Copy: 3365/3365 100.0%; Applied: 435; Backlog: 0/100
0; Time: 3s(total), 2s(copy); streamer: mysql-bin.000001:81714074; State: migrating; ETA: due')
on duplicate key update
last_update=NOW(),
value=VALUES(value)
..
2019-02-25T08:39:00.374467Z 67 Query insert /* gh-ost */ into `mysqlslap`.`_t1_ghc`
(id, hint, value)
values
(NULLIF(1, 0), 'heartbeat', '2019-02-25T17:39:00.374212828+09:00')
on duplicate key update
last_update=NOW(),
value=VALUES(value)
..
- ghcの方は制御情報を書き込んでるっぽいのかな。
2019-02-25T08:38:59.221449Z 67 Query select /* gh-ost `mysqlslap`.`t1` iteration:4 */
`id`
from
`mysqlslap`.`t1`
where ((`id` > _binary'ca4dbc9a-38d8-11e9-98dc-0201a32caf75')) and ((`id` < _binary'ca4dbc9a-3
8d8-11e9-98dc-0201a32caf75') or ((`id` = _binary'ca4dbc9a-38d8-11e9-98dc-0201a32caf75')))
order by
`id` asc
limit 1
offset 999
2019-02-25T08:38:59.221871Z 66 Query select /* gh-ost `mysqlslap`.`t1` iteration:4 */ `id`
from (
select
`id`
from
`mysqlslap`.`t1`
where ((`id` > _binary'ca4dbc9a-38d8-11e9-98dc-0201a32caf75')) and ((`id` < _binary'ca
4dbc9a-38d8-11e9-98dc-0201a32caf75') or ((`id` = _binary'ca4dbc9a-38d8-11e9-98dc-0201a32caf75')))
order by
`id` asc
limit 1000
) select_osc_chunk
order by
`id` desc
limit 1
--chunk-sizeぶんの行を探している気配がする。--concurrent-rowcount=true（デフォルト）の時はcount rows after row-copy begins, concurrently, and adjust row estimate later onらしいのでその処理かしらん。
- general_logを眺めていたら
DROPが ghc なテーブルにしか流れてなかったことに気が付く。
master [localhost] {msandbox} (mysqlslap) > SHOW TABLES;
+---------------------+
| Tables_in_mysqlslap |
+---------------------+
| _t1_del |
| t1 |
+---------------------+
2 rows in set (0.00 sec)
- デフォルトではスワップさせた旧テーブルはDROPしないっぽい。
pt-online-schema-changeはデフォルトで旧テーブルをDROPするのでそれを知らないとたまにアイタタタタってなるけれど- 容量問題にぶち当たっている場合はこれを憶えておかないとアイタタタタってなると思うので憶えておこう
取り敢えず今日はここまで。
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