TiDB Lightning Requirements for the Target Database

Before using TiDB Lightning, you need to check whether the environment meets the requirements. This helps reduce errors during import and ensures import success.

Privileges of the target database

Based on the import mode and features enabled, the target database users should be granted with different privileges. The following table provides a reference.

	Feature	Scope	Required privilege	Remarks
Mandatory	Basic functions	Target table	CREATE, SELECT, INSERT, UPDATE, DELETE, DROP, ALTER, REFERENCES	DROP is required only when tidb-lightning-ctl runs the checkpoint-destroy-all command
Mandatory	Basic functions	Target database	CREATE
Mandatory	Logical Import Mode	information_schema.columns	SELECT
	Physical Import Mode	mysql.tidb	SELECT
		-	SUPER
		-	RESTRICTED_VARIABLES_ADMIN,RESTRICTED_TABLES_ADMIN	Required when the target TiDB enables SEM
Recommended	Conflict detection, max-error	Schema configured for lightning.task-info-schema-name	SELECT, INSERT, UPDATE, DELETE, CREATE, DROP	If not required, the value must be set to ""
Optional	Parallel import	Schema configured for lightning.meta-schema-name	SELECT, INSERT, UPDATE, DELETE, CREATE, DROP	If not required, the value must be set to ""
Optional	checkpoint.driver = "mysql"	checkpoint.schema setting	SELECT,INSERT,UPDATE,DELETE,CREATE,DROP	Required when checkpoint information is stored in databases, instead of files

Note

If the target table does not use the foreign key, the REFERENCES privilege is not required.
If the target table uses the foreign key, you need to grant the REFERENCES privilege for the downstream database user, or manually create the target table in the downstream database in advance to ensure smooth data import.

Storage space of the target database

The target TiKV cluster must have enough disk space to store the imported data. In addition to the standard hardware requirements, the storage space of the target TiKV cluster must be larger than the size of the data source x the number of replicas x 2. For example, if the cluster uses 3 replicas by default, the target TiKV cluster must have a storage space larger than 6 times the size of the data source. The formula has x 2 because:

Indexes might take extra space.
RocksDB has a space amplification effect.

It is difficult to calculate the exact data volume exported by Dumpling from MySQL. However, you can estimate the data volume by using the following SQL statement to summarize the data-length field in the information_schema.tables table:

Calculate the size of all schemas, in MiB. Replace ${schema_name} with your schema name.

SELECT table_schema, SUM(data_length)/1024/1024 AS data_length, SUM(index_length)/1024/1024 AS index_length, SUM(data_length+index_length)/1024/1024 AS sum FROM information_schema.tables WHERE table_schema = "${schema_name}" GROUP BY table_schema;

Calculate the size of the largest table, in MiB. Replace ${schema_name} with your schema name.

SELECT table_name, table_schema, SUM(data_length)/1024/1024 AS data_length, SUM(index_length)/1024/1024 AS index_length,sum(data_length+index_length)/1024/1024 AS sum FROM information_schema.tables WHERE table_schema = "${schema_name}" GROUP BY table_name,table_schema ORDER BY sum DESC LIMIT 5;

TiDB Lightning Requirements for the Target Database

Privileges of the target database

Storage space of the target database

Was this page helpful?