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Data Check for Tables with Different Schema or Table Names
Learn the data check for different database names or table names.
/docs/dev/sync-diff-inspector/route-diff/
/docs/dev/reference/tools/sync-diff-inspector/route-diff/

Data Check for Tables with Different Schema or Table Names

When using replication tools such as TiDB Data Migration, you can set route-rules to replicate data to a specified table in the downstream. sync-diff-inspector enables you to verify tables with different schema names or table names by setting rules.

The following is a simple configuration example. To learn the complete configuration, refer to sync-diff-inspector User Guide.

######################### Datasource config #########################
[data-sources.mysql1]
    host = "127.0.0.1"
    port = 3306
    user = "root"
    password = ""
    route-rules = ["rule1"]

[data-sources.tidb0]
    host = "127.0.0.1"
    port = 4000
    user = "root"
    password = ""
########################### Routes ###########################
[routes.rule1]
schema-pattern = "test_1"      # Matches the schema name of the data source. Supports the wildcards "*" and "?"
table-pattern = "t_1"          # Matches the table name of the data source. Supports the wildcards "*" and "?"
target-schema = "test_2"       # The name of the schema in the target database
target-table = "t_2"           # The name of the target table

This configuration can be used to check test_2.t_2 in the downstream and test_1.t_1 in the mysql1 instance.

To check a large number of tables with different schema names or table names, you can simplify the configuration by setting the mapping relationship by using rules. You can configure the mapping relationship of either schema or table, or of both. For example, all the tables in the upstream test_1 database are replicated to the downstream test_2 database, which can be checked through the following configuration:

######################### Datasource config #########################
[data-sources.mysql1]
    host = "127.0.0.1"
    port = 3306
    user = "root"
    password = ""
    route-rules = ["rule1"]

[data-sources.tidb0]
    host = "127.0.0.1"
    port = 4000
    user = "root"
    password = ""
########################### Routes ###########################
[routes.rule1]
schema-pattern = "test_1"      # Matches the schema name of the data source. Supports the wildcards "*" and "?"
table-pattern = "*"            # Matches the table name of the data source. Supports the wildcards "*" and "?"
target-schema = "test_2"       # The name of the schema in the target database
target-table = "t_2"           # The name of the target table

The initialization of table routers and some examples

The initialization of table routers

  • If a target-schema/target-table table named schema.table exists in the rules, the behavior of sync-diff-inspector is as follows:

    • If there is a rule that matches schema.table to schema.table, sync-diff-inspector does nothing.
    • If there is no rule that matches schema.table to schema.table, sync-diff-inspector will add a new rule schema.table -> _no__exists__db_._no__exists__table_ to the table router. After that, sync-diff-inspector will treat the table schema.table as the table _no__exists__db_._no__exists__table_.

  • If target-schema exists only in the rules as follows:

    [routes.rule1]
schema-pattern = "schema_2"  # the schema to match. Support wildcard characters * and ?
target-schema = "schema"     # the target schema
    • If there is no schema schema in the upstream, sync-diff-inspector does nothing.
    • If there is a schema schema in the upstream, and a rule matches the schema, sync-diff-inspector does nothing.
    • If there is a schema schema in the upstream, but no rule matches the schema, sync-diff-inspector will add a new rule schema -> _no__exists__db_ to the table router. After that, sync-diff-inspector will treat the table schema as the table _no__exists__db_.

  • If target-schema.target-table does not exist in the rules, sync-diff-inspector will add a rule to match target-schema.target-table to target-schema.target-table to make it case-insensitive, because the table router is case-insensitive.

Examples

Suppose there are seven tables in the upstream cluster:

  • inspector_mysql_0.tb_emp1
  • Inspector_mysql_0.tb_emp1
  • inspector_mysql_0.Tb_emp1
  • inspector_mysql_1.tb_emp1
  • Inspector_mysql_1.tb_emp1
  • inspector_mysql_1.Tb_emp1
  • Inspector_mysql_1.Tb_emp1

In the configuration example, the upstream cluster has a rule Source.rule1, and the target table is inspector_mysql_1.tb_emp1.

Example 1

If the configuration is as follows:

[Source.rule1]
schema-pattern = "inspector_mysql_0"
table-pattern = "tb_emp1"
target-schema = "inspector_mysql_1"
target-table = "tb_emp1"

The routing results will be as follows:

  • inspector_mysql_0.tb_emp1 is routed to inspector_mysql_1.tb_emp1
  • Inspector_mysql_0.tb_emp1 is routed to inspector_mysql_1.tb_emp1
  • inspector_mysql_0.Tb_emp1 is routed to inspector_mysql_1.tb_emp1
  • inspector_mysql_1.tb_emp1 is routed to _no__exists__db_._no__exists__table_
  • Inspector_mysql_1.tb_emp1 is routed to _no__exists__db_._no__exists__table_
  • inspector_mysql_1.Tb_emp1 is routed to _no__exists__db_._no__exists__table_
  • Inspector_mysql_1.Tb_emp1 is routed to _no__exists__db_._no__exists__table_

Example 2

If the configuration is as follows:

[Source.rule1]
schema-pattern = "inspector_mysql_0"
target-schema = "inspector_mysql_1"

The routing results will be as follows:

  • inspector_mysql_0.tb_emp1 is routed to inspector_mysql_1.tb_emp1
  • Inspector_mysql_0.tb_emp1 is routed to inspector_mysql_1.tb_emp1
  • inspector_mysql_0.Tb_emp1 is routed to inspector_mysql_1.Tb_emp1
  • inspector_mysql_1.tb_emp1 is routed to _no__exists__db_._no__exists__table_
  • Inspector_mysql_1.tb_emp1 is routed to _no__exists__db_._no__exists__table_
  • inspector_mysql_1.Tb_emp1 is routed to _no__exists__db_._no__exists__table_
  • Inspector_mysql_1.Tb_emp1 is routed to _no__exists__db_._no__exists__table_

Example 3

If the configuration is as follows:

[Source.rule1]
schema-pattern = "other_schema"
target-schema = "other_schema"

The routing results will be as follows:

  • inspector_mysql_0.tb_emp1 is routed to inspector_mysql_0.tb_emp1
  • Inspector_mysql_0.tb_emp1 is routed to Inspector_mysql_0.tb_emp1
  • inspector_mysql_0.Tb_emp1 is routed to inspector_mysql_0.Tb_emp1
  • inspector_mysql_1.tb_emp1 is routed to inspector_mysql_1.tb_emp1
  • Inspector_mysql_1.tb_emp1 is routed to inspector_mysql_1.tb_emp1
  • inspector_mysql_1.Tb_emp1 is routed to inspector_mysql_1.tb_emp1
  • Inspector_mysql_1.Tb_emp1 is routed to inspector_mysql_1.tb_emp1

Example 4

If the configuration is as follows:

[Source.rule1]
schema-pattern = "inspector_mysql_?"
table-pattern = "tb_emp1"
target-schema = "inspector_mysql_1"
target-table = "tb_emp1"

The routing results will be as follows:

  • inspector_mysql_0.tb_emp1 is routed to inspector_mysql_1.tb_emp1
  • Inspector_mysql_0.tb_emp1 is routed to inspector_mysql_1.tb_emp1
  • inspector_mysql_0.Tb_emp1 is routed to inspector_mysql_1.tb_emp1
  • inspector_mysql_1.tb_emp1 is routed to inspector_mysql_1.tb_emp1
  • Inspector_mysql_1.tb_emp1 is routed to inspector_mysql_1.tb_emp1
  • inspector_mysql_1.Tb_emp1 is routed to inspector_mysql_1.tb_emp1
  • Inspector_mysql_1.Tb_emp1 is routed to inspector_mysql_1.tb_emp1

Example 5

If you do not set any rules, the routing results will be as follows:

  • inspector_mysql_0.tb_emp1 is routed to inspector_mysql_0.tb_emp1
  • Inspector_mysql_0.tb_emp1 is routed to Inspector_mysql_0.tb_emp1
  • inspector_mysql_0.Tb_emp1 is routed to inspector_mysql_0.Tb_emp1
  • inspector_mysql_1.tb_emp1 is routed to inspector_mysql_1.tb_emp1
  • Inspector_mysql_1.tb_emp1 is routed to inspector_mysql_1.tb_emp1
  • inspector_mysql_1.Tb_emp1 is routed to inspector_mysql_1.tb_emp1
  • Inspector_mysql_1.Tb_emp1 is routed to inspector_mysql_1.tb_emp1