gh-ost

• gh-ost is built-in GoInception. No additional installation. About Stop, Pause, Recover are contained in GoInception command.
• Support calling gh-ost in binary mode, the parameter switch is ghost_bin_dir, please refer to the osc_bin_dir parameter of pt-osc for usage, if this parameter is not specified, it will still be called with the built-in gh-ost.

Options

gh-ost tool Option check in inception show variables like 'ghost%'`;

inception show variables like 'ghost%';

Modify in two ways:

• one at inception set

inception set osc_check_interval = 10;

• another one at config.toml, and start by -config=config.toml

Process command

check osc process

inception get osc processlist;

results return:

DBNAME	TABLENAME	COMMAND	SQLSHA1	PERCENT	REMAINTIME	INFOMATION
test_inc	t1	alter table t1 add column c33 int	*E53542EFF4E179BE267210114EC5EDBEF9DC5D8F	9	00:36	Copying test_inc.t1: 9% 00:36 remain

check specific osc process

inception get osc_percent '*E53542EFF4E179BE267210114EC5EDBEF9DC5D8F';

results return:

DBNAME	TABLENAME	SQLSHA1	PERCENT	REMAINTIME	INFOMATION
test_inc	t1	*E53542EFF4E179BE267210114EC5EDBEF9DC5D8F	49	00:14	Copying test_inc.t1: 49% 00:14 remain

stop specific osc process

need to remove auxiliary tables manual

inception kill osc '*E53542EFF4E179BE267210114EC5EDBEF9DC5D8F';
-- or --
inception stop alter '*E53542EFF4E179BE267210114EC5EDBEF9DC5D8F';

pause specific osc process

inception pause osc '*E53542EFF4E179BE267210114EC5EDBEF9DC5D8F';
-- or --
inception pause alter '*E53542EFF4E179BE267210114EC5EDBEF9DC5D8F';

recover specific osc process

inception resume osc '*E53542EFF4E179BE267210114EC5EDBEF9DC5D8F';
-- or --
inception resume alter '*E53542EFF4E179BE267210114EC5EDBEF9DC5D8F';

reuse pt-osc options

Options	default	type	description
osc_critical_thread_connected	1000	int	correspond to --critical-load中的thread_connected
osc_critical_thread_running	80	int	correspond to --critical-load中的thread_running
osc_max_thread_connected	1000	int	correspond to --max-load中的thread_connected
osc_max_thread_running	80	int	correspond --max-load中的thread_running
osc_min_table_size	16	int	Switch set，if value is 0, all ALTER will use OSC.if values is not 0, only the table size more than the values, use OSC. unit in MB，table size = select (DATA_LENGTH + INDEX_LENGTH)/1024/1024 from information_schema.tables where table_schema = "dbname" and table_name = "tablename"
osc_print_none	false	bool	If value is 1, do not print. If values is 0, print osc output in inception result error sets.

Option descriptions

Option	default	type	description
ghost_on	false	bool	gh-ost swtich
ghost_bin_dir v1.2.5	''	string	gh-ost binary path
ghost_aliyun_rds	false	bool	Ali rds database label
ghost_allow_master_master	false	bool	If gh-ost can run in Dual master structure, with option -assume-master-host
ghost_allow_nullable_unique_key	FALSE	bool	If gh-ost can depend on Unique key in NULL when migrate.Default unique key can not be NULL.If yes, data will inconsistency in migration.
ghost_allow_on_master	TRUE	bool	If gh-ost can run on Master.Default on Master
ghost_approve_renamed_columns	TRUE	bool	If support to change column name.Default false.
ghost_assume_master_host		string	Gh-ost Maser db addr (hostname:port or ip:port).Default gh-ost connect to Slave.
ghost_assume_rbr	TRUE	bool	When the server that gh-ost connect binlog_format = ROW, can use -assume-rbr to probit run stop/start slave on Slave and the user of gh-ost don't need super privileges. Warning: avoid any effect to live db, set true.
ghost_chunk_size	1000	int	The row number in each loop.Default 1000. Range in [100, 100000]
ghost_concurrent_rowcount	TRUE	bool	If value is true(default), estimate table rows by explain select count(*) after row-copy，and reject the time of ETA. If value is false, gh-ost will estimate table rows first and then row-copy.
ghost_critical_load_hibernate_seconds	0	int	Reach critical-load, in sleep.
ghost_critical_load_interval_millis	0	int	if the value is 0，exit immediately when reach the -critical-load. If the value is not 0, wait -critical-load-interval-millis when reach -critical-load and check again, if reach again, exit.
ghost_cut_over	atomic	string	The type of cut-over: atomic(default) use github algorithm. two-step use facebook-OSC algorithm
ghost_cut_over_exponential_backoff	FALSE	bool	Wait exponentially longer intervals between failed cut-over attempts. Wait intervals obey a maximum configurable with 'exponential-backoff-max-interval').
ghost_cut_over_lock_timeout_seconds	3	int	The lock wait timeout when cut-over stage, when timeout, will retry. Default 3.
ghost_default_retries	60	int	Retry times before panic at many actions. Default 60.
ghost_discard_foreign_keys	FALSE	bool	For foreign key table, gh-ost create will not contain the foreign key. Only use for remove the foreign key.
ghost_dml_batch_size	10	int	How many DML in one transaction. Range in [1,100]. Default 10.
ghost_exact_rowcount	FALSE	bool	Exactly estimate table rows by select count(*).
ghost_exponential_backoff_max_interval	64	int	Maximum number of seconds to wait between attempts when performing various operations with exponential backoff. (default 64)
ghost_force_named_cut_over	FALSE	bool	When true, the ‘unpostpone
ghost_force_table_names		string	table name prefix to be used on the temporary tables
ghost_gcp	FALSE	bool	Google Cloud support.
ghost_heartbeat_interval_millis	500	int	Gh-ost heartbeat values, default 500ms.
ghost_initially_drop_ghost_table	FALSE	bool	If check and delete a existing ghost table. Warning: do not use it in live env, maybe delete the ghost table in a running gh-ost. Manual check and delete.
ghost_initially_drop_old_table	FALSE	bool	If check and delete old-table when start gh-ost. Warning: do not use it in live env, maybe delete the table in a running gh-ost. Manual check and delete.
ghost_initially_drop_socket_file	FALSE	bool	Gh-ost will force delete the existing socket file. Warning: do not use it in live env, maybe delete the socket file of a running gh-ost.
ghost_max_lag_millis	1500	int	When slave latency more the the value, gh-ost will throttling. Default 1500ms.
ghost_nice_ratio	0	float	Sleep time at each chunk time. Range in [0.0...100.0]. E.g: 0: no sleep; 1: bewteen each row-copy 1ms, sleep 1ms; 0.7: bewteen row-copy 10ms, sleep 7ms.
ghost_ok_to_drop_table	TRUE	bool	If drop old-table, when gh-ost finished. Default true
ghost_postpone_cut_over_flag_file		string	Cut-over stage will be delayed when this file exists until this file is deleted.
ghost_replication_lag_query		string	Check latency by show slave status Seconds_behind_master. If use pt-heartbeat, sql = SELECT ROUND(UNIX_TIMESTAMP() - MAX(UNIX_TIMESTAMP(ts))) AS delay FROM my_schema.heartbeat
ghost_skip_foreign_key_checks	TRUE	bool	Skip foreign key check, default true.
ghost_throttle_additional_flag_file		string	Gh-ost will stop immediately when this file is created.Used to stop all gh-ost executions. Delete this file, recover all gh-ost executions.
ghost_throttle_control_replicas		string	List all slaves which need to check why latency.
ghost_throttle_flag_file		string	Gh-ost will stop immediately when this file is created. Used for control single gh-ost execution. --throttle-additional-flag-file string used for muil-execution.
ghost_throttle_http		string	The --throttle-http flag allows for throttling via HTTP. Every 100ms gh-ost issues a HEAD request to the provided URL. If the response status code is not 200 throttling will kick in until a 200 response status code is returned.
ghost_throttle_query		string	Flow check at every minute. When the value is 0, don't need throttling. When the value >0, need throttling. This query will run on a migrated server, please keep it lightly.
ghost_timestamp_old_table	FALSE	bool	Use timestamp in old-tablename, keep unique name
ghost_tungsten	FALSE	bool	Tell gh-ost running in a tungsten-replication structure