IMPORT INTO

The IMPORT INTO statement lets you import data to TiDB via the Physical Import Mode of TiDB Lightning. You can use IMPORT INTO in the following two ways:

• IMPORT INTO ... FROM FILE: imports data files in formats such as CSV, SQL, and PARQUET into an empty table in TiDB.
• IMPORT INTO ... FROM SELECT: imports the query result of a SELECT statement into an empty table in TiDB. You can also use it to import historical data queried with AS OF TIMESTAMP.

Restrictions

• IMPORT INTO only supports importing data into existing empty tables in the database.
• IMPORT INTO does not support transactions or rollback. Executing IMPORT INTO within an explicit transaction (BEGIN/END) will return an error.
• IMPORT INTO does not support working simultaneously with features such as Backup & Restore, FLASHBACK CLUSTER, acceleration of adding indexes, data import using TiDB Lightning, data replication using TiCDC, or Point-in-Time Recovery (PITR).
• During the data import process, do not perform DDL or DML operations on the target table, and do not execute FLASHBACK DATABASE for the target database. These operations can lead to import failures or data inconsistencies. In addition, it is NOT recommended to perform read operations during the import process, as the data being read might be inconsistent. Perform read and write operations only after the import is completed.
• The import process consumes system resources significantly. For TiDB Self-Hosted, to get better performance, it is recommended to use TiDB nodes with at least 32 cores and 64 GiB of memory. TiDB writes sorted data to the TiDB temporary directory during import, so it is recommended to configure high-performance storage media for TiDB Self-Hosted, such as flash memory. For more information, see Physical Import Mode limitations.
• For TiDB Self-Hosted, the TiDB temporary directory is expected to have at least 90 GiB of available space. It is recommended to allocate storage space that is equal to or greater than the volume of data to be imported.
• One import job supports importing data into one target table only.
• IMPORT INTO is not supported during TiDB cluster upgrades.
• Ensure that the data to be imported does not contain any records with primary key or non-null unique index conflicts. Otherwise, the conflicts can result in import task failures.
• Known issue: the IMPORT INTO task might fail if the PD address in the TiDB node configuration file is inconsistent with the current PD topology of the cluster. This inconsistency can arise in situations such as that PD was scaled in previously, but the TiDB configuration file was not updated accordingly or the TiDB node was not restarted after the configuration file update.

IMPORT INTO ... FROM FILE restrictions

• For TiDB Self-Hosted, each IMPORT INTO task supports importing data within 10 TiB. If you enable the Global Sort feature, each IMPORT INTO task supports importing data within 40 TiB.
• For TiDB Dedicated, if your data to be imported exceeds 500 GiB, it is recommended to use TiDB nodes with at least 16 cores and enable the Global Sort feature, then each IMPORT INTO task supports importing data within 40 TiB. If your data to be imported is within 500 GiB or if the cores of your TiDB nodes are less than 16, it is not recommended to enable the Global Sort feature.
• The execution of IMPORT INTO ... FROM FILE blocks the current connection until the import is completed. To execute the statement asynchronously, you can add the DETACHED option.
• Up to 16 IMPORT INTO tasks can run simultaneously on each cluster (see TiDB Distributed eXecution Framework (DXF) usage limitations). When a cluster lacks sufficient resources or reaches the maximum number of tasks, newly submitted import tasks are queued for execution.
• When the Global Sort feature is used for data import, the value of the THREAD option must be at least 16.
• When the Global Sort feature is used for data import, the data size of a single row after encoding must not exceed 32 MiB.
• All IMPORT INTO tasks that are created when TiDB Distributed eXecution Framework (DXF) is not enabled run directly on the nodes where the tasks are submitted, and these tasks will not be scheduled for execution on other TiDB nodes even after DXF is enabled later. After DXF is enabled, only newly created IMPORT INTO tasks that import data from S3 or GCS are automatically scheduled or failed over to other TiDB nodes for execution.

IMPORT INTO ... FROM SELECT restrictions

• IMPORT INTO ... FROM SELECT can only be executed on the TiDB node that the current user is connected to, and it blocks the current connection until the import is complete.
• IMPORT INTO ... FROM SELECT only supports two import options: THREAD and DISABLE_PRECHECK.
• IMPORT INTO ... FROM SELECT does not support the task management statements such as SHOW IMPORT JOB(s) and CANCEL IMPORT JOB <job-id>.
• The temporary directory of TiDB requires sufficient space to store the entire query result of the SELECT statement (configuring the DISK_QUOTA option is not supported currently).
• Importing historical data using tidb_snapshot is not supported.

Prerequisites for import

Before using IMPORT INTO to import data, make sure the following requirements are met:

• The target table to be imported is already created in TiDB and it is empty.
• The target cluster has sufficient space to store the data to be imported.
• For TiDB Self-Hosted, the temporary directory of the TiDB node connected to the current session has at least 90 GiB of available space. If tidb_enable_dist_task is enabled and the data for import is from S3 or GCS, also make sure that the temporary directory of each TiDB node in the cluster has sufficient disk space.

Required privileges

Executing IMPORT INTO requires the SELECT, UPDATE, INSERT, DELETE, and ALTER privileges on the target table. To import files in TiDB local storage, the FILE privilege is also required.

Synopsis

ImportIntoStmt ::=
    'IMPORT' 'INTO' TableName ColumnNameOrUserVarList? SetClause? FROM fileLocation Format? WithOptions?
    |
    'IMPORT' 'INTO' TableName ColumnNameList? FROM SelectStatement WithOptions?

ColumnNameOrUserVarList ::=
    '(' ColumnNameOrUserVar (',' ColumnNameOrUserVar)* ')'

ColumnNameList ::=
    '(' ColumnName (',' ColumnName)* ')'

SetClause ::=
    'SET' SetItem (',' SetItem)*

SetItem ::=
    ColumnName '=' Expr

Format ::=
    'CSV' | 'SQL' | 'PARQUET'

WithOptions ::=
    'WITH' OptionItem (',' OptionItem)*

OptionItem ::=
    optionName '=' optionVal | optionName

Parameter description

ColumnNameOrUserVarList

It specifies how each field in the data file corresponds to the columns in the target table. You can also use it to map fields to variables to skip certain fields for the import, or use it in SetClause.

• If this parameter is not specified, the number of fields in each row of the data file must match the number of columns in the target table, and the fields will be imported to the corresponding columns in order.
• If this parameter is specified, the number of specified columns or variables must match the number of fields in each row of the data file.

SetClause

It specifies how the values of target columns are calculated. In the right side of the SET expression, you can reference the variables specified in ColumnNameOrUserVarList.

In the left side of the SET expression, you can only reference a column name that is not included in ColumnNameOrUserVarList. If the target column name already exists in ColumnNameOrUserVarList, the SET expression is invalid.

fileLocation

It specifies the storage location of the data file, which can be an Amazon S3 or GCS URI path, or a TiDB local file path.

• Amazon S3 or GCS URI path: for URI configuration details, see URI Formats of External Storage Services.

• TiDB local file path: it must be an absolute path, and the file extension must be .csv, .sql, or .parquet. Make sure that the files corresponding to this path are stored on the TiDB node connected by the current user, and the user has the FILE privilege.

In the fileLocation parameter, you can specify a single file, or use the * and [] wildcards to match multiple files for import. Note that the wildcard can only be used in the file name, because it does not match directories or recursively match files in subdirectories. Taking files stored on Amazon S3 as examples, you can configure the parameter as follows:

• Import a single file: s3://<bucket-name>/path/to/data/foo.csv
• Import all files in a specified path: s3://<bucket-name>/path/to/data/*
• Import all files with the .csv suffix in a specified path: s3://<bucket-name>/path/to/data/*.csv
• Import all files with the foo prefix in a specified path: s3://<bucket-name>/path/to/data/foo*
• Import all files with the foo prefix and the .csv suffix in a specified path: s3://<bucket-name>/path/to/data/foo*.csv
• Import 1.csv and 2.csv in a specified path: s3://<bucket-name>/path/to/data/[12].csv

Format

The IMPORT INTO statement supports three data file formats: CSV, SQL, and PARQUET. If not specified, the default format is CSV.

WithOptions

You can use WithOptions to specify import options and control the data import process. For example, to execute the import of data files asynchronously in the backend, you can enable the DETACHED mode for the import by adding the WITH DETACHED option to the IMPORT INTO statement.

The supported options are described as follows:

IMPORT INTO ... FROM FILE usage

For TiDB Self-Hosted, IMPORT INTO ... FROM FILE supports importing data from files stored in Amazon S3, GCS, and the TiDB local storage. For TiDB Dedicated, IMPORT INTO ... FROM FILE supports importing data from files stored in Amazon S3 and GCS.

• For data files stored in Amazon S3 or GCS, IMPORT INTO ... FROM FILE supports running in the TiDB Distributed eXecution Framework (DXF).

  • When the DXF is enabled (tidb_enable_dist_task is ON), IMPORT INTO splits a data import job into multiple sub-jobs and distributes these sub-jobs to different TiDB nodes for execution to improve the import efficiency.
  • When the DXF is disabled, IMPORT INTO ... FROM FILE only supports running on the TiDB node where the current user is connected.

• For data files stored locally in TiDB, IMPORT INTO ... FROM FILE only supports running on the TiDB node where the current user is connected. Therefore, the data files need to be placed on the TiDB node where the current user is connected. If you access TiDB through a proxy or load balancer, you cannot import data files stored locally in TiDB.

Compressed files

IMPORT INTO ... FROM FILE supports importing compressed CSV and SQL files. It can automatically determine whether a file is compressed and the compression format based on the file extension:

Global Sort

IMPORT INTO ... FROM FILE splits the data import job of a source data file into multiple sub-jobs, each sub-job independently encoding and sorting data before importing. If the encoded KV ranges of these sub-jobs have significant overlap (to learn how TiDB encodes data to KV, see TiDB computing), TiKV needs to keep compaction during import, leading to a decrease in import performance and stability.

In the following scenarios, there can be significant overlap in KV ranges:

• If rows in the data file assigned to each sub-job have overlapping primary key ranges, the data KV generated by the encoding of each sub-job will also overlap.
  • IMPORT INTO splits sub-jobs based on the traversal order of data files, usually sorted by file name in lexicographic order.
• If the target table has many indexes, or the index column values are scattered in the data file, the index KV generated by the encoding of each sub-job will also overlap.

When the TiDB Distributed eXecution Framework (DXF) is enabled, you can enable Global Sort by specifying the CLOUD_STORAGE_URI option in the IMPORT INTO statement or by specifying the target storage address for encoded KV data using the system variable tidb_cloud_storage_uri. Currently, Global Sort supports using Amazon S3 as the storage address. When Global Sort is enabled, IMPORT INTO writes encoded KV data to the cloud storage, performs Global Sort in the cloud storage, and then parallelly imports the globally sorted index and table data into TiKV. This prevents problems caused by KV overlap and enhances import stability and performance.

Global Sort consumes a significant amount of memory resources. Before the data import, it is recommended to configure the tidb_server_memory_limit_gc_trigger and tidb_server_memory_limit variables, which avoids golang GC being frequently triggered and thus affecting the import efficiency.

SET GLOBAL tidb_server_memory_limit_gc_trigger=1;
SET GLOBAL tidb_server_memory_limit='75%';

Output

When IMPORT INTO ... FROM FILE completes the import or when the DETACHED mode is enabled, TiDB returns the current job information in the output, as shown in the following examples. For the description of each field, see SHOW IMPORT JOB(s).

When IMPORT INTO ... FROM FILE completes the import, the example output is as follows:

IMPORT INTO t FROM '/path/to/small.csv';
+--------+--------------------+--------------+----------+-------+----------+------------------+---------------+----------------+----------------------------+----------------------------+----------------------------+------------+
| Job_ID | Data_Source        | Target_Table | Table_ID | Phase | Status   | Source_File_Size | Imported_Rows | Result_Message | Create_Time                | Start_Time                 | End_Time                   | Created_By |
+--------+--------------------+--------------+----------+-------+----------+------------------+---------------+----------------+----------------------------+----------------------------+----------------------------+------------+
|  60002 | /path/to/small.csv | `test`.`t`   |      363 |       | finished | 16B              |             2 |                | 2023-06-08 16:01:22.095698 | 2023-06-08 16:01:22.394418 | 2023-06-08 16:01:26.531821 | root@%     |
+--------+--------------------+--------------+----------+-------+----------+------------------+---------------+----------------+----------------------------+----------------------------+----------------------------+------------+

When the DETACHED mode is enabled, executing the IMPORT INTO ... FROM FILE statement will immediately return the job information in the output. From the output, you can see that the status of the job is pending, which means waiting for execution.

IMPORT INTO t FROM '/path/to/small.csv' WITH DETACHED;
+--------+--------------------+--------------+----------+-------+---------+------------------+---------------+----------------+----------------------------+------------+----------+------------+
| Job_ID | Data_Source        | Target_Table | Table_ID | Phase | Status  | Source_File_Size | Imported_Rows | Result_Message | Create_Time                | Start_Time | End_Time | Created_By |
+--------+--------------------+--------------+----------+-------+---------+------------------+---------------+----------------+----------------------------+------------+----------+------------+
|  60001 | /path/to/small.csv | `test`.`t`   |      361 |       | pending | 16B              |          NULL |                | 2023-06-08 15:59:37.047703 | NULL       | NULL     | root@%     |
+--------+--------------------+--------------+----------+-------+---------+------------------+---------------+----------------+----------------------------+------------+----------+------------+

View and manage import jobs

For an import job with the DETACHED mode enabled, you can use SHOW IMPORT to view its current job progress.

After an import job is started, you can cancel it using CANCEL IMPORT JOB <job-id>.

Examples

Import a CSV file with headers

IMPORT INTO t FROM '/path/to/file.csv' WITH skip_rows=1;

Import a file asynchronously in the DETACHED mode

IMPORT INTO t FROM '/path/to/file.csv' WITH DETACHED;

Skip importing a specific field in your data file

Assume that your data file is in the CSV format and its content is as follows:

id,name,age
1,Tom,23
2,Jack,44

And assume that the target table schema for the import is CREATE TABLE t(id int primary key, name varchar(100)). To skip importing the age field in the data file to the table t, you can execute the following SQL statement:

IMPORT INTO t(id, name, @1) FROM '/path/to/file.csv' WITH skip_rows=1;

Import multiple data files using wildcards

Assume that there are three files named file-01.csv, file-02.csv, and file-03.csv in the /path/to/ directory. To import these three files into a target table t using IMPORT INTO, you can execute the following SQL statement:

IMPORT INTO t FROM '/path/to/file-*.csv';

If you only need to import file-01.csv and file-03.csv into the target table, execute the following SQL statement:

IMPORT INTO t FROM '/path/to/file-0[13].csv';

Import data files from Amazon S3 or GCS

• Import data files from Amazon S3:

  IMPORT INTO t FROM 's3://bucket-name/test.csv?access-key=XXX&secret-access-key=XXX';
  

• Import data files from GCS:

  IMPORT INTO t FROM 'gs://import/test.csv?credentials-file=${credentials-file-path}';
  

For details about the URI path configuration for Amazon S3 or GCS, see URI Formats of External Storage Services.

Calculate column values using SetClause

Assume that your data file is in the CSV format and its content is as follows:

id,name,val
1,phone,230
2,book,440

And assume that the target table schema for the import is CREATE TABLE t(id int primary key, name varchar(100), val int). If you want to multiply the val column values by 100 during the import, you can execute the following SQL statement:

IMPORT INTO t(id, name, @1) SET val=@1*100 FROM '/path/to/file.csv' WITH skip_rows=1;

Import a data file in the SQL format

IMPORT INTO t FROM '/path/to/file.sql' FORMAT 'sql';

Limit the write speed to TiKV

To limit the write speed to a TiKV node to 10 MiB/s, execute the following SQL statement:

IMPORT INTO t FROM 's3://bucket/path/to/file.parquet?access-key=XXX&secret-access-key=XXX' FORMAT 'parquet' WITH MAX_WRITE_SPEED='10MiB';

IMPORT INTO ... FROM SELECT usage

IMPORT INTO ... FROM SELECT lets you import the query result of a SELECT statement to an empty table in TiDB. You can also use it to import historical data queried with AS OF TIMESTAMP.

Import the query result of SELECT

To import the UNION result to the target table t, with the import concurrency specified as 8 and precheck of non-critical items configured as disabled, execute the following SQL statement:

IMPORT INTO t FROM SELECT * FROM src UNION SELECT * FROM src2 WITH THREAD = 8, DISABLE_PRECHECK;

Import historical data at a specified time point

To import historical data at a specified time point to the target table t, execute the following SQL statement:

IMPORT INTO t FROM SELECT * FROM src AS OF TIMESTAMP '2024-02-27 11:38:00';

MySQL compatibility

This statement is a TiDB extension to MySQL syntax.

See also

• SHOW IMPORT JOB(s)
• CANCEL IMPORT JOB