Data migration: Add migration-overview.md

migration-overview.md

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+---
+title: Migration Overview
+summary: This document describes how to migrate data from databases or data formats (CSV/SQL).
+category: reference
+---
+
+# Migration Overview
+
+This document describes how to migrate data to TiDB, including migrating data from MySQL and from CSV/SQL files.
+
+## Migrate from MySQL to TiDB
+
+To migrate data from MySQL to TiDB, it is recommended to use one of the following methods:
+
+- [Use Mydumper and TiDB Lightning](#use-mydumper-and-tidb-lightning-full-data) to migrate full data.
+- [Use TiDB Data Migration (DM)](#use-dm) to migrate full and incremental data.
+
+### Use Mydumper and TiDB Lightning (full data)
+
+#### Scenarios
+
+You can use Mydumper and TiDB Lightning to migrate full data when the data size is greater than 1 TB. If you need to replicate incremental data, it is recommended to [use DM](#use-dm) to create an incremental replication task.
+
+#### Migration method
+
+1. Use Mydumper to export the full MySQL data.
+2. Use TiDB Lightning to import the full data to TiDB. For details, refer to [Migrate from Mydumper Files](/migrate-from-mysql-mydumper-files.md).
+
+### Use DM
+
+#### Scenarios
+
+You can use DM to migrate full MySQL data and to replicate incremental data. It is suggested that the size of the full data is less than 1 TB. Otherwise, it is recommended to use Mydumper and TiDB Lightning to import the full data, and then use DM to replicate the incremental data.
+
+#### Migration method
+
+For details, refer to [Migrate from MySQL (Amazon Aurora)](/migrate-from-aurora-mysql-database.md)
+
+## Migrate data from files to TiDB
+
+You can migrate data from CSV/SQL files to TiDB.
+
+### Migrate data from CSV files to TiDB
+
+#### Scenarios
+
+You can migrate data from heterogeneous databases that are not compatible with the MySQL protocol to TiDB.
+
+#### Migration method
+
+1. Export full data to CSV files.
+2. Import CSV files to TiDB using one of the following methods:
+
+    - Use TiDB Lightning.
+
+        Its import speed is fast. It is recommended to use TiDB Lightning in the case of large amounts of data in CSV files. For details, refer to [TiDB Lightning CSV Support](/tidb-lightning/migrate-from-csv-using-tidb-lightning.md).
+
+    - Use the `LOAD DATA` statement.
+
+        Execute the `LOAD DATA` statement in TiDB to import CSV files. This is more convenient, but if an error or interruption occurs during the import, manual intervention is required to check the consistency and integrity of the data. Therefore, it is **not recommended** to use this method in the production environment. For details, refer to [LOAD DATA](/sql-statements/sql-statement-load-data.md).
+
+### Migrate data from SQL files to TiDB
+
+Use Mydumper and TiDB Lightning to migrate data from SQL files to TiDB. For details, refer to [Use Mydumper and TiDB Lightning](#use-mydumper-and-tidb-lightning-full-data).