loadertool to export and import all the data
You can use
mydumper to export data from MySQL and
loader to import the data into TiDB.
Although TiDB also supports the official
mysqldumptool from MySQL for data migration, it is not recommended to use it. Its performance is much lower than
loaderand it takes much time to migrate large amounts of data.
loaderis more powerful. For more information, see https://github.com/maxbube/mydumper.
mydumper tool to export data from MySQL by using the following command:
./bin/mydumper -h 127.0.0.1 -P 3306 -u root -t 16 -F 64 -B test -T t1,t2 --skip-tz-utc -o ./var/test
In this command,
-B test: means the data is exported from the
-T t1,t2: means only the
t2tables are exported.
-t 16: means 16 threads are used to export the data.
-F 64: means a table is partitioned into chunks and one chunk is 64MB.
--skip-tz-utc: the purpose of adding this parameter is to ignore the inconsistency of time zone setting between MySQL and the data exporting machine and to disable automatic conversion.
On the Cloud platforms which require the
super privilege, such as on the Aliyun platform, add the
--no-locksparameter to the command. If not, you might get the error message that you don’t have the privilege.
loader to import the data from MySQL to TiDB. See Loader instructions for more information.
./bin/loader -h 127.0.0.1 -u root -P 4000 -t 32 -d ./var/test
After the data is imported, you can view the data in TiDB using the MySQL client:
mysql -h127.0.0.1 -P4000 -uroot mysql> show tables; +----------------+ | Tables_in_test | +----------------+ | t1 | | t2 | +----------------+ mysql> select * from t1; +----+------+ | id | age | +----+------+ | 1 | 1 | | 2 | 2 | | 3 | 3 | +----+------+ mysql> select * from t2; +----+------+ | id | name | +----+------+ | 1 | a | | 2 | b | | 3 | c | +----+------+
To migrate data quickly, especially for huge amount of data, you can refer to the following recommendations.
-Fparameter to set the value.
loaderbased on the number and the load of TiKV instances. For example, if there are three TiKV instances,
-tcan be set to 3 * (1 ~ n). If the load of TiKV is too high and the log
backoffer.maxSleep 15000ms is exceededis displayed many times, decrease the value of
-t; otherwise, increase it.
mydumperis set to 16 and the
loaderis set to 64.
Results: It takes 11 hours to import all the data, which is 19.4G/hour.
syncertool to import data incrementally (optional)
The previous section introduces how to import all the history data from MySQL to TiDB using
loader. But this is not applicable if the data in MySQL is updated after the migration and it is expected to import the updated data quickly.
Therefore, TiDB provides the
syncer tool for an incremental data import from MySQL to TiDB.
See Download the TiDB enterprise toolset to download the
# Download the enterprise tool package. wget http://download.pingcap.org/tidb-enterprise-tools-latest-linux-amd64.tar.gz wget http://download.pingcap.org/tidb-enterprise-tools-latest-linux-amd64.sha256 # Check the file integrity. If the result is OK, the file is correct. sha256sum -c tidb-enterprise-tools-latest-linux-amd64.sha256 # Extract the package. tar -xzf tidb-enterprise-tools-latest-linux-amd64.tar.gz cd tidb-enterprise-tools-latest-linux-amd64
Assuming the data from
t2 is already imported to TiDB using
loader. Now we hope that any updates to these two tables are replicated to TiDB in real time.
The data exported from MySQL contains a metadata file which includes the position information. Take the following metadata information as an example:
Started dump at: 2017-04-28 10:48:10 SHOW MASTER STATUS: Log: mysql-bin.000003 Pos: 930143241 GTID: Finished dump at: 2017-04-28 10:48:11
The position information (
Pos: 930143241) needs to be stored in the
syncer.meta file for
syncer to replicate:
# cat syncer.meta binlog-name = "mysql-bin.000003" binlog-pos = 930143241
syncer.metafile only needs to be configured once when it is first used. The position will be automatically updated when binlog is replicated.
config.toml file for
log-level = "info" server-id = 101 # The file path for meta: meta = "./syncer.meta" worker-count = 16 batch = 10 # The testing address for pprof. It can also be used by Prometheus to pull the syncer metrics. status-addr = ":10081" skip-sqls = ["ALTER USER", "CREATE USER"] # Support whitelist filter. You can specify the database and table to be replicated. For example: # Replicate all the tables of db1 and db2: replicate-do-db = ["db1","db2"] # Replicate db1.table1. [[replicate-do-table]] db-name ="db1" tbl-name = "table1" # Replicate db3.table2. [[replicate-do-table]] db-name ="db3" tbl-name = "table2" # Support regular expressions. Start with '~' to use regular expressions. # To replicate all the databases that start with `test`: replicate-do-db = ["~^test.*"] # The sharding replicating rules support wildcharacter. # 1. The asterisk character (*, also called "star") matches zero or more characters, # for example, "doc*" matches "doc" and "document" but not "dodo"; # asterisk character must be in the end of the wildcard word, # and there is only one asterisk in one wildcard word. # 2. The question mark ? matches exactly one character. #[[route-rules]] #pattern-schema = "route_*" #pattern-table = "abc_*" #target-schema = "route" #target-table = "abc" #[[route-rules]] #pattern-schema = "route_*" #pattern-table = "xyz_*" #target-schema = "route" #target-table = "xyz" [from] host = "127.0.0.1" user = "root" password = "" port = 3306 [to] host = "127.0.0.1" user = "root" password = "" port = 4000
./bin/syncer -config config.toml 2016/10/27 15:22:01 binlogsyncer.go:226: [info] begin to sync binlog from position (mysql-bin.000003, 1280) 2016/10/27 15:22:01 binlogsyncer.go:130: [info] register slave for master server 127.0.0.1:3306 2016/10/27 15:22:01 binlogsyncer.go:552: [info] rotate to (mysql-bin.000003, 1280) 2016/10/27 15:22:01 syncer.go:549: [info] rotate binlog to (mysql-bin.000003, 1280)
INSERT INTO t1 VALUES (4, 4), (5, 5);
mysql -h127.0.0.1 -P4000 -uroot -p mysql> select * from t1; +----+------+ | id | age | +----+------+ | 1 | 1 | | 2 | 2 | | 3 | 3 | | 4 | 4 | | 5 | 5 | +----+------+
syncer outputs the current replicated data statistics every 30 seconds:
2017/06/08 01:18:51 syncer.go:934: [info] [syncer]total events = 15, total tps = 130, recent tps = 4, master-binlog = (ON.000001, 11992), master-binlog-gtid=53ea0ed1-9bf8-11e6-8bea-64006a897c73:1-74, syncer-binlog = (ON.000001, 2504), syncer-binlog-gtid = 53ea0ed1-9bf8-11e6-8bea-64006a897c73:1-17 2017/06/08 01:19:21 syncer.go:934: [info] [syncer]total events = 15, total tps = 191, recent tps = 2, master-binlog = (ON.000001, 11992), master-binlog-gtid=53ea0ed1-9bf8-11e6-8bea-64006a897c73:1-74, syncer-binlog = (ON.000001, 2504), syncer-binlog-gtid = 53ea0ed1-9bf8-11e6-8bea-64006a897c73:1-35
You can see that by using
syncer, the updates in MySQL are automatically replicated in TiDB.