MySQL Online modify table structure tool Gh-ost

Gh-ost Use test:

gh-ost-host= ' 192.168.65.136 '-user=root-password= '-database= ' haha '-chunk-size=100000-allow-on-master-execute- Initially-drop-ghost-table-exact-rowcount--initially-drop-old-table-alter= ' modify Areaid varchar (ten) '-table= ' T_ Policyarea '

-allow-master-Master explicitly allows running in the primary primary cluster-allow-on-Master allows to run directly on the host, if no cluster uses this option, it is recommended to use on-machine-alterstring(mandatory parameter) ALTER statement such as ADD column_name type, change column_name column_name type, modify column_name type; ALTER TABLE string Required-assume-RBR Settings'true'When you are sure to use'ROW'Binlog_format. -chunk-sizeintthe number of rows processed per iteration, which is 1000 by default, allows the range ( --100000)-concurrent-RowCount ( with--exact-rowcount), whentrue: Count rows After row-copy begins, concurrently, and adjust row estimate later on; Defaultsfalse: First count rows, ThenStart Row Copy-confstringconfiguration file-critical-load--max-Load , set a threshold, and the application will automatically exit if the threshold value is exceeded.--max-load Same meaning-databasestringdatabase name must be field-Debug Debug Mode-default-retriesintnumber of retries before a variety of accidents (default -)    -exact-ROWCOUNT copy the number of row before the exact estimate, in order to facilitate accurate comment on the execution progress: this is not necessary, accurate statistics for large tables is also very time-consuming-execute actually executes the change, and if this option is not added by default it is tested and then exited, and the original table structure is not changed .-hoststringMySQL host name, preferably from the machine instead of the host (default"127.0.0.1")    -initially-drop-ghost-Table if you have run multiple changes to the same table, there will be a ghost table, using this option to delete the existing ghost table-initially-drop-old-table effect above, default is interrupt stop-initially-drop-socket-fileforcibly delete the existing socket file.            Caution: This may delete the socket file that is running the migration! -max-loadstringcommand format e.g:'threads_running=100,threads_connected=500'when the server reaches this load, it will reduce the resources used to modify-migrate-on-Replica has the migration run on a replica and not on the master. this would DoThe full migration on the replica includingCut-over (as opposed to--test-on-replica)- Nice-ratiofloatForce being' Nice', implySleep  TimePer chunk Time; Range: [0.0..100.0]. Example values:0Is aggressive.1: forEvery 1ms spent copying rows,SleepAdditional 1ms (effectively doubling runtime);0.7: forEvery 10ms spendincha rowcopy chunk, spend 7ms sleeping immediately after-ok-to-drop-Delete old table after table, because delete will have a long time lock, online operation is not recommended, default is False-panic-flag-file string when thisfileis created, gh-OST would immediately terminate, without cleanup-passwordstringMySQL server password-portintMySQL server port, recommended to operate from the machine-stack trace is added on error-switch-to-RBR let the tool automatically switch binary log format to'ROW'On the replica,ifNeeded. The format is not being switched back. I ' m too scared to DoThat, and wish to protect youifYou happen to execute another migration whileThis one is running-tablestringrequired parameter, table name-throttle-querystringdetect once per second to ensure that it is a lightweight query that does not have a large impact on the server-Tungsten explicitly let GH-ost know that is running on a tungsten-replication based topology (you is likely to also provide--assume-master-host)-userstringMySQL user-verbose redundant output details-Version number-test-on-Replica has the migration run on a replica and not on the master. At the end of migration replication was stopped, and tables are swapped and immediately swap-revert. Replication remains stopped and you can compare the both tables forBuilding Trust-test-on-replica-skip-replica-Stop when--test-on-replica is enabled, DoNot issue commands stop replication (requires--test-on-replica)-throttle-additional-flag-file stringoperation pauses when thisfileExists Hint:keep Default, use forThrottling multiple Gh-ost operations (default"/tmp/gh-ost.throttle")    -throttle-control-replicasstringList of Replicas onwhichTo check forLag Comma Delimited. Example:myhost1.com:3306, myhost2.com,myhost3.com:3307-throttle-flag-file stringoperation pauses when thisfileExists Hint:use AfileThat's specific to the table being altered-postpone-Cut-over-flag-file string         whileThisfileexists, migration would postpone the final stage of swapping tables, and would keep on syncing the ghost table. Cut-over/swapping would is ready to perform the moment thefileis deleted. -Quiet Quiet-replication-lag-querystringQuery that detects replication laginchSeconds. Result can is a floating point (by default gh-ost issues SHOW SLAVE STATUS and reads Seconds_behind_master). If You're using pt-heartbeat, query would be something Like:select ROUND (Unix_timestamp ()-MAX (Unix_timestamp (TS))) as Dela Y from My_schema.heartbeat-serve-socket-file stringUnix socketsfileTo serve on. default:auto-determined and advertised upon startup-serve-tcp-portintTCP port to serve on. Default:disabled-skip-renamed-Columns ALTERinch  CaseYour ALTER statement renames columns, Gh-ost would note that and an offer to its interpretation of the rename. By default Gh-ost does not proceed to execute. This flag tells Gh-ost to skip the renamed columns, i.e. to treat what gh-OST thinks is renamed columns as unrelated columns. Note:you may lose column data-approve-renamed-Columns ALTERinch  CaseYour ALTER statement renames columns, Gh-ost would note that and an offer to its interpretation of the rename. By default Gh-ost does not proceed to execute. This flag approves that Gh-ost's interpretation si correct-assume-master-hoststring(optional) explicitly tell GH-ost the identity of the master. format:some.host.com[:p ORT] This is usefulinchMaster-master setups where you wish to pick an explicit master, orinchA tungsten-replicator where gh-OST is unabel to determine the master-Cut-overstringChooseCut-over type (default|atomic, two-step) (default"Atomic")    -Cut-over-lock-timeout-secondsintMax number of seconds to hold locks on tables whileAttempting toCut-over (retry attempted when lock exceeds timeout) (default3)     -heartbeat-interval-millisintHow frequently would gh-ost inject a heartbeat value (default -)    -hooks-hintstringarbitrary message to being injected to hooks via Gh_ost_hooks_hint, forYour convenience-hooks-pathstringdirectory where hook files are found (default:empty, ie. hooks disabled). Hook files found on this path, and conforming to hook naming conventions would be executed-max-lag-millisintreplication Lag atwhichTo throttle operation (default the)      

MySQL Online modify table structure tool Gh-ost