# gh-ost

  • gh-ost is built-in GoInception. No additional installation.
  • About Stop, Pause, Recover are contained in GoInception command.

# 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:

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:

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_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