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:
β | 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 Methodsβ
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:
β | 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 | S3, HDFS | LOCAL |
SELECT INTO OUTFILEβ
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.
EXPORTβ
Suitable for the following scenarios:
- Large-scale single table export, with simple filtering conditions.
- Scenarios that require asynchronous task submission.
MySQL Dumpβ
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 Mappingβ
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:
-
ORC
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 json string variant string bitmap binary quantile_state binary hll binary -
Parquet
When Doris is exported to the Parquet file format, the Doris memory data is first converted to the Arrow memory data format, and then written out to the Parquet file format by Arrow.
Doris Type Arrow Type Parquet Physical Type Parquet Logical Type boolean boolean BOOLEAN tinyint int8 INT32 INT_8 smallint int16 INT32 INT_16 int int32 INT32 INT_32 bigint int64 INT64 INT_64 largeInt utf8 BYTE_ARRAY UTF8 date utf8 BYTE_ARRAY UTF8 datev2 date32 INT32 DATE datetime utf8 BYTE_ARRAY UTF8 datetimev2 timestamp INT96/INT64 TIMESTAMP(MICROS/MILLIS/SECONDS) float float32 FLOAT double float64 DOUBLE char / varchar / string utf8 BYTE_ARRAY UTF8 decimal decimal128 FIXED_LEN_BYTE_ARRAY DECIMAL(scale, precision) struct struct Parquet Group map map Parquet Map array list Parquet List json utf8 BYTE_ARRAY UTF8 variant utf8 BYTE_ARRAY UTF8 bitmap binary BYTE_ARRAY quantile_state binary BYTE_ARRAY hll binary BYTE_ARRAY Note: In versions 2.1.11 and 3.0.7, you can specify the
parquet.enable_int96_timestamps
property to determine whether Doris's datetimev2 type uses Parquet's INT96 storage or INT64. INT96 is used by default. However, INT96 has been deprecated in the Parquet standard and is only used for compatibility with some older systems (such as versions before Hive 4.0).