Export Overview

The data export function is used to write the query result set or Doris table data into the specified storage system in the specified file format.

The differences between the export function and the data backup function are as follows:

	Data Export	Data Backup
Final Storage Location	HDFS, Object Storage, Local File System	HDFS, Object Storage
Data Format	Open file formats such as Parquet, ORC, CSV	Doris internal storage format
Execution Speed	Moderate (requires reading data and converting to the target data format)	Fast (no parsing and conversion required, directly upload Doris data files)
Flexibility	Can flexibly define the data to be exported through SQL statements	Only supports table-level full backup
Use Cases	Result set download, data exchange between different systems	Data backup, data migration between Doris clusters

Choosing Export Methods

Doris provides three different data export methods:

• SELECT INTO OUTFILE: Supports the export of any SQL result set.
• EXPORT: Supports the export of partial or full table data.
• MySQL DUMP: Compatible with the MySQL dump command for data export.

The similarities and differences between the three export methods are as follows:

	SELECT INTO OUTFILE	EXPORT	MySQL DUMP
Synchronous/Asynchronous	Synchronous	Asynchronous (submit EXPORT tasks and check task progress via SHOW EXPORT command)	Synchronous
Supports any SQL	Yes	No	No
Export specific partitions	Yes	Yes	No
Export specific tablets	Yes	No	No
Concurrent export	Supported with high concurrency (depends on whether the SQL statement has operators such as ORDER BY that need to be processed on a single node)	Supported with high concurrency (supports tablet-level concurrent export)	Not supported, single-threaded export only
Supported export data formats	Parquet, ORC, CSV	Parquet, ORC, CSV	MySQL Dump proprietary format
Supports exporting external tables	Yes	Partially supported	No
Supports exporting views	Yes	Yes	Yes
Supported export locations	S3, HDFS, LOCAL	S3, HDFS, LOCAL	LOCAL

SELECT INTO OUTFILE

Suitable for the following scenarios:

• Data needs to be exported after complex calculations, such as filtering, aggregation, joins, etc.
• Suitable for scenarios that require synchronous tasks.

EXPORT

Suitable for the following scenarios:

• Large-scale single table export, with simple filtering conditions.
• Scenarios that require asynchronous task submission.

MySQL Dump

Suitable for the following scenarios:

• Compatible with the MySQL ecosystem, requires exporting both table structure and data.
• Only for development testing or scenarios with very small data volumes.

Export File Column Type Mapping

Parquet and ORC file formats have their own data types. Doris's export function can automatically map Doris's data types to the corresponding data types in Parquet and ORC file formats. The CSV format does not have types, all data is output as text.

The following table shows the mapping between Doris data types and Parquet, ORC file format data types:

1. Doris export to ORC file format data type mapping table: | Doris Type | Orc Type | | ----- | ----- | | boolean | boolean | | tinyint | tinyint | | smallint | smallint | | int | int | | bigint | bigint | | largeInt | string | | date | string | | datev2 | string | | datetime | string | | datetimev2 | timestamp | | float | float | | double | double | | char / varchar / string | string | | decimal | decimal | | struct | struct | | map | map | | array | array |

2. When Doris exports to Parquet file format, it first converts Doris in-memory data to Arrow in-memory data format, then writes out to Parquet file format. The mapping relationship between Doris data types and Arrow data types is:

   Doris Type	Arrow Type
   boolean	boolean
   tinyint	int8
   smallint	int16
   int	int32
   bigint	int64
   largeInt	utf8
   date	utf8
   datev2	Date32Type
   datetime	utf8
   datetimev2	TimestampType
   float	float32
   double	float64
   char / varchar / string	utf8
   decimal	decimal128
   struct	struct
   map	map
   array	list