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Dumpling Overview
Use the Dumpling tool to export data from TiDB.
/docs/dev/mydumper-overview/
/docs/dev/reference/tools/mydumper/
/tidb/dev/mydumper-overview/

Use Dumpling to Export Data

This document introduces the data export tool - Dumpling. Dumpling exports data stored in TiDB/MySQL as SQL or CSV data files and can be used to make a logical full backup or export. Dumpling also supports exporting data to Amazon S3.

You can get Dumpling using TiUP by running tiup install dumpling. Afterwards, you can use tiup dumpling ... to run Dumpling.

The Dumpling installation package is included in the TiDB Toolkit. To download the TiDB Toolkit, see Download TiDB Tools.

You can install Dumpling using the following commands:

curl --proto '=https' --tlsv1.2 -sSf https://tiup-mirrors.pingcap.com/install.sh | sh
source ~/.bash_profile
tiup install dumpling

In the above commands, you need to modify ~/.bash_profile to the path of your profile file.

For detailed usage of Dumpling, use the --help option or refer to Option list of Dumpling.

When using Dumpling, you need to execute the export command on a running cluster.

TiDB also provides other tools that you can choose to use as needed.

  • For backups of SST files (key-value pairs) or backups of incremental data that are not sensitive to latency, refer to BR.
  • For real-time backups of incremental data, refer to TiCDC.
  • All exported data can be imported back to TiDB using TiDB Lightning.

Note:

PingCAP previously maintained a fork of the mydumper project with enhancements specific to TiDB. This fork has since been replaced by Dumpling, which has been rewritten in Go, and supports more optimizations that are specific to TiDB. It is strongly recommended that you use Dumpling instead of mydumper.

For more information on Mydumper, refer to v4.0 Mydumper documentation.

Compared to Mydumper, Dumpling has the following improvements:

  • Support exporting data in multiple formats, including SQL and CSV.
  • Support the table-filter feature, which makes it easier to filter data.
  • Support exporting data to Amazon S3 cloud storage.
  • More optimizations are made for TiDB:
    • Support configuring the memory limit of a single TiDB SQL statement.
    • If Dumpling can connect directly to PD, Dumpling supports automatic adjustment of TiDB GC time for TiDB v4.0.0 and later versions.
    • Use TiDB's hidden column _tidb_rowid to optimize the performance of concurrent data export from a single table.
    • For TiDB, you can set the value of tidb_snapshot to specify the time point of the data backup. This ensures the consistency of the backup, instead of using FLUSH TABLES WITH READ LOCK to ensure the consistency.

Note:

Dumpling cannot connect to PD in the following scenarios:

  • The TiDB cluster is running on Kubernetes (unless Dumpling itself is run inside the Kubernetes environment).
  • The TiDB cluster is running on TiDB Cloud.

In such cases, you need to manually adjust the TiDB GC time to avoid export failure.

Export data from TiDB or MySQL

Required privileges

  • PROCESS: Required to query the cluster information to obtain the PD address and then control GC via the PD.
  • SELECT: Required when exporting tables.
  • RELOAD: Required when using consistency flush. Note that only TiDB supports this privilege. When the upstream is an RDS database or a managed service, you can ignore this privilege.
  • LOCK TABLES: Required when using consistency lock. This privilege must be granted for all the databases and tables to be exported.
  • REPLICATION CLIENT: Required when exporting metadata to record data snapshot. This privilege is optional and you can ignore it if you do not need to export metadata.

Export to SQL files

This document assumes that there is a TiDB instance on the 127.0.0.1:4000 host and that this TiDB instance has a root user without a password.

Dumpling exports data to SQL files by default. You can also export data to SQL files by adding the --filetype sql flag:

{{< copyable "shell-regular" >}}

dumpling -u root -P 4000 -h 127.0.0.1 --filetype sql -t 8 -o /tmp/test -r 200000 -F 256MiB

In the command above:

  • The -h, -P, and -u option respectively mean the address, the port, and the user. If a password is required for authentication, you can use -p $YOUR_SECRET_PASSWORD to pass the password to Dumpling.
  • The -o (or --output) option specifies the export directory of the storage, which supports an absolute local file path or an external storage URI.
  • The -o (or --output) option specifies the export directory of the storage, which supports an absolute local file path or an external storage URI.
  • The -t option specifies the number of threads for the export. Increasing the number of threads improves the concurrency of Dumpling and the export speed, and also increases the database's memory consumption. Therefore, it is not recommended to set the number too large. Usually, it's less than 64.
  • The -r option enables the in-table concurrency to speed up the export. The default value is 0, which means disabled. A value greater than 0 means it is enabled, and the value is of INT type. When the source database is TiDB, a -r value greater than 0 indicates that the TiDB region information is used for splitting, and reduces the memory usage. The specific -r value does not affect the split algorithm. When the source database is MySQL and the primary key is of the INT type, specifying -r can also enable the in-table concurrency.
  • The -F option is used to specify the maximum size of a single file (the unit here is MiB; inputs like 5GiB or 8KB are also acceptable). It is recommended to keep its value to 256 MiB or less if you plan to use TiDB Lightning to load this file into a TiDB instance.

Note:

If the size of a single exported table exceeds 10 GB, it is strongly recommended to use the -r and -F options.

Export to CSV files

You can export data to CSV files by adding the --filetype csv argument.

When you export data to CSV files, you can use --sql <SQL> to filter the records with the SQL statements. For example, you can export all records that match id < 100 in test.sbtest1 using the following command:

{{< copyable "shell-regular" >}}

./dumpling -u root -P 4000 -h 127.0.0.1 -o /tmp/test --filetype csv --sql 'select * from `test`.`sbtest1` where id < 100' -F 100MiB --output-filename-template 'test.sbtest1.{{.Index}}'

In the command above:

  • The --sql option can be used only for exporting to CSV files. The command above executes the SELECT * FROM <table-name> WHERE id <100 statement on all tables to be exported. If a table does not have the specified field, the export fails.
  • When you use the --sql option, Dumpling cannot obtain the exported table and schema information. You can specify the file name format of the CSV files using the --output-filename-template option, which facilitates the subsequent use of TiDB Lightning to import the data file. For example, --output-filename-template='test.sbtest1.{{.Index}}' specifies that the exported CSV files are named as test.sbtest1.000000000 or test.sbtest1.000000001.
  • When you use the --sql option, Dumpling cannot obtain the exported table and schema information. You can specify the file name format of the CSV files using the --output-filename-template option. For example, --output-filename-template='test.sbtest1.{{.Index}}' specifies that the exported CSV files are named as test.sbtest1.000000000 or test.sbtest1.000000001.
  • You can use options like --csv-separator and --csv-delimiter to configure the CSV file format. For details, refer to the Dumpling option list.

Note:

Strings and keywords are not distinguished by Dumpling. If the imported data is the Boolean type, the value of true is converted to 1 and the value of false is converted to 0.

Compress the exported data files

You can use the --compress <format> option to compress the CSV and SQL data and table structure files exported by Dumpling. This parameter supports the following compression algorithms: gzip, snappy, and zstd. The compression is disabled by default.

  • This option only compresses individual data and table structure files. It cannot compress the entire folder and generate a single compressed package.
  • This option can save disk space, but it also slows down the export speed and increases CPU consumption. Use this option with caution in scenarios where the export speed is critical.
  • For TiDB Lightning v6.5.0 and later versions, you can use compressed files exported by Dumpling as the data source without additional configuration.

Format of exported files

  • metadata: The start time of the exported files and the position of the master binary log.

    {{< copyable "shell-regular" >}}

    cat metadata
    Started dump at: 2020-11-10 10:40:19
SHOW MASTER STATUS:
        Log: tidb-binlog
        Pos: 420747102018863124
Finished dump at: 2020-11-10 10:40:20

  • {schema}-schema-create.sql: The SQL file used to create the schema

    {{< copyable "shell-regular" >}}

    cat test-schema-create.sql
    CREATE DATABASE `test` /*!40100 DEFAULT CHARACTER SET utf8mb4 */;

  • {schema}.{table}-schema.sql: The SQL file used to create the table

    {{< copyable "shell-regular" >}}

    cat test.t1-schema.sql
    CREATE TABLE `t1` (
  `id` int(11) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin;

  • {schema}.{table}.{0001}.{sql|csv}: The date source file

    {{< copyable "shell-regular" >}}

    cat test.t1.0.sql
    /*!40101 SET NAMES binary*/;
INSERT INTO `t1` VALUES
(1);

  • *-schema-view.sql, *-schema-trigger.sql, *-schema-post.sql: Other exported files

Export data to Amazon S3 cloud storage

Starting from v4.0.8, Dumpling supports exporting data to cloud storages. If you need to back up data to Amazon S3, you need to specify the Amazon S3 storage path in the -o parameter.

You need to create an Amazon S3 bucket in the specified region (see the Amazon documentation - How do I create an S3 Bucket). If you also need to create a folder in the bucket, see the Amazon documentation - Creating a folder.

Pass SecretKey and AccessKey of the account with the permission to access the Amazon S3 backend storage to the Dumpling node as environment variables.

{{< copyable "shell-regular" >}}

export AWS_ACCESS_KEY_ID=${AccessKey}
export AWS_SECRET_ACCESS_KEY=${SecretKey}

Dumpling also supports reading credential files from ~/.aws/credentials. Parameters for exporting data to Amazon S3 using Dumpling are the same as the parameters used in BR. For more parameter descriptions, see external storage URI.

Dumpling also supports reading credential files from ~/.aws/credentials. Parameters for exporting data to Amazon S3 using Dumpling are the same as the parameters used in BR. For more parameter descriptions, see external storage URI.

{{< copyable "shell-regular" >}}

./dumpling -u root -P 4000 -h 127.0.0.1 -r 200000 -o "s3://${Bucket}/${Folder}"

Filter the exported data

Use the --where option to filter data

By default, Dumpling exports all databases except system databases (including mysql, sys, INFORMATION_SCHEMA, PERFORMANCE_SCHEMA, METRICS_SCHEMA, and INSPECTION_SCHEMA). You can use --where <SQL where expression> to select the records to be exported.

{{< copyable "shell-regular" >}}

./dumpling -u root -P 4000 -h 127.0.0.1 -o /tmp/test --where "id < 100"

The above command exports the data that matches id < 100 from each table. Note that you cannot use the --where parameter together with --sql.

Use the --filter option to filter data

Dumpling can filter specific databases or tables by specifying the table filter with the --filter option. The syntax of table filters is similar to that of .gitignore. For details, see Table Filter.

{{< copyable "shell-regular" >}}

./dumpling -u root -P 4000 -h 127.0.0.1 -o /tmp/test -r 200000 --filter "employees.*" --filter "*.WorkOrder"

The above command exports all the tables in the employees database and the WorkOrder tables in all databases.

Use the -B or -T option to filter data

Dumpling can also export specific databases with the -B option or specific tables with the -T option.

Note:

  • The --filter option and the -T option cannot be used at the same time.
  • The -T option can only accept a complete form of inputs like database-name.table-name, and inputs with only the table name are not accepted. Example: Dumpling cannot recognize -T WorkOrder.

Examples:

  • -B employees exports the employees database.
  • -T employees.WorkOrder exports the employees.WorkOrder table.

Improve export efficiency through concurrency

The exported file is stored in the ./export-<current local time> directory by default. Commonly used options are as follows:

  • The -t option specifies the number of threads for the export. Increasing the number of threads improves the concurrency of Dumpling and the export speed, and also increases the database's memory consumption. Therefore, it is not recommended to set the number too large.
  • The -r option enables the in-table concurrency to speed up the export. The default value is 0, which means disabled. A value greater than 0 means it is enabled, and the value is of INT type. When the source database is TiDB, a -r value greater than 0 indicates that the TiDB region information is used for splitting, and reduces the memory usage. The specific -r value does not affect the split algorithm. When the source database is MySQL and the primary key is of the INT type, specifying -r can also enable the in-table concurrency.
  • The --compress <format> option specifies the compression format of the dump. It supports the following compression algorithms: gzip, snappy, and zstd. This option can speed up dumping of data if storage is the bottleneck or if storage capacity is a concern. The drawback is an increase in CPU usage. Each file is compressed individually.

With the above options specified, Dumpling can have a quicker speed of data export.

Adjust Dumpling's data consistency options

Note:

The default value is auto for the data consistency option. In most scenarios, you do not need to adjust the default data consistency options of Dumpling.

Dumpling uses the --consistency <consistency level> option to control the way in which data is exported for "consistency assurance". When using snapshot for consistency, you can use the --snapshot option to specify the timestamp to be backed up. You can also use the following levels of consistency:

  • flush: Use FLUSH TABLES WITH READ LOCK to temporarily interrupt the DML and DDL operations of the replica database, to ensure the global consistency of the backup connection, and to record the binlog position (POS) information. The lock is released after all backup connections start transactions. It is recommended to perform full backups during off-peak hours or on the MySQL replica database.
  • snapshot: Get a consistent snapshot of the specified timestamp and export it.
  • lock: Add read locks on all tables to be exported.
  • none: No guarantee for consistency.
  • auto: Use flush for MySQL and snapshot for TiDB.

After everything is done, you can see the exported file in /tmp/test:

{{< copyable "shell-regular" >}}

ls -lh /tmp/test | awk '{print $5 "\t" $9}'
140B  metadata
66B   test-schema-create.sql
300B  test.sbtest1-schema.sql
190K  test.sbtest1.0.sql
300B  test.sbtest2-schema.sql
190K  test.sbtest2.0.sql
300B  test.sbtest3-schema.sql
190K  test.sbtest3.0.sql

Export historical data snapshots of TiDB

Dumpling can export the data of a certain tidb_snapshot with the --snapshot option specified.

The --snapshot option can be set to a TSO (the Position field output by the SHOW MASTER STATUS command) or a valid time of the datetime data type (in the form of YYYY-MM-DD hh:mm:ss), for example:

{{< copyable "shell-regular" >}}

./dumpling --snapshot 417773951312461825
./dumpling --snapshot "2020-07-02 17:12:45"

The TiDB historical data snapshots when the TSO is 417773951312461825 and the time is 2020-07-02 17:12:45 are exported.

Control the memory usage of exporting large tables

When Dumpling is exporting a large single table from TiDB, Out of Memory (OOM) might occur because the exported data size is too large, which causes connection abort and export failure. You can use the following parameters to reduce the memory usage of TiDB:

  • Setting -r to split the data to be exported into chunks. This reduces the memory overhead of TiDB's data scan and enables concurrent table data dump to improve export efficiency. When the upstream database is TiDB v3.0 or later versions, a -r value greater than 0 indicates that the TiDB region information is used for splitting and the specific -r value does not affect the split algorithm.
  • Reduce the value of --tidb-mem-quota-query to 8589934592 (8 GB) or lower. --tidb-mem-quota-query controls the memory usage of a single query statement in TiDB.
  • Adjust the --params "tidb_distsql_scan_concurrency=5" parameter. tidb_distsql_scan_concurrency is a session variable which controls the concurrency of the scan operations in TiDB.

Manually set the TiDB GC time

When exporting data from TiDB (more than 1 TB), if the TiDB version is later than or equal to v4.0.0 and Dumpling can access the PD address of the TiDB cluster, Dumpling automatically extends the GC time without affecting the original cluster.

However, in either of the following scenarios, Dumpling cannot automatically adjust the GC time:

  • The data size is very large (more than 1 TB).
  • Dumpling cannot connect directly to PD, for example, if the TiDB cluster is on TiDB Cloud or on Kubernetes that is separated from Dumpling.

In such scenarios, you must manually extend the GC time in advance to avoid export failure due to GC during the export process.

To manually adjust the GC time, use the following SQL statement:

SET GLOBAL tidb_gc_life_time = '720h';

After Dumpling exits, regardless of whether the export is successful or not, you must set the GC time back to its original value (the default value is 10m).

SET GLOBAL tidb_gc_life_time = '10m';

Option list of Dumpling

Options Usage Default value
-V or --version Output the Dumpling version and exit directly
-B or --database Export specified databases
-T or --tables-list Export specified tables
-f or --filter Export tables that match the filter pattern. For the filter syntax, see table-filter. [\*.\*,!/^(mysql&#124;sys&#124;INFORMATION_SCHEMA&#124;PERFORMANCE_SCHEMA&#124;METRICS_SCHEMA&#124;INSPECTION_SCHEMA)$/.\*] (export all databases or tables excluding system schemas)
--case-sensitive whether table-filter is case-sensitive false (case-insensitive)
-h or --host The IP address of the connected database host "127.0.0.1"
-t or --threads The number of concurrent backup threads 4
-r or --rows Enable the in-table concurrency to speed up the export. The default value is 0, which means disabled. A value greater than 0 means it is enabled, and the value is of INT type. When the source database is TiDB, a -r value greater than 0 indicates that the TiDB region information is used for splitting, and reduces the memory usage. The specific -r value does not affect the split algorithm. When the source database is MySQL and the primary key is of the INT type, specifying -r can also enable the in-table concurrency.
-L or --logfile Log output address. If it is empty, the log will be output to the console ""
--loglevel Log level {debug,info,warn,error,dpanic,panic,fatal} "info"
--logfmt Log output format {text,json} "text"
-d or --no-data Do not export data (suitable for scenarios where only the schema is exported)
--no-header Export CSV files of the tables without generating header
-W or --no-views Do not export the views true
-m or --no-schemas Do not export the schema with only the data exported
-s or --statement-size Control the size of the INSERT statements; the unit is bytes
-F or --filesize The file size of the divided tables. The unit must be specified such as 128B, 64KiB, 32MiB, and 1.5GiB.
--filetype Exported file type (csv/sql) "sql"
-o or --output Specify the absolute local file path or external storage URI for exporting the data. "./export-${time}"
-S or --sql Export data according to the specified SQL statement. This command does not support concurrent export.
--consistency flush: use FTWRL before the dump
snapshot: dump the TiDB data of a specific snapshot of a TSO
lock: execute lock tables read on all tables to be dumped
none: dump without adding locks, which cannot guarantee consistency
auto: use --consistency flush for MySQL; use --consistency snapshot for TiDB		 "auto"
--snapshot Snapshot TSO; valid only when consistency=snapshot
--where Specify the scope of the table backup through the where condition
-p or --password The password of the connected database host
-P or --port The port of the connected database host 4000
-u or --user The username of the connected database host "root"
--dump-empty-database Export the CREATE DATABASE statements of the empty databases true
--ca The address of the certificate authority file for TLS connection
--cert The address of the client certificate file for TLS connection
--key The address of the client private key file for TLS connection
--csv-delimiter Delimiter of character type variables in CSV files '"'
--csv-separator Separator of each value in CSV files. It is not recommended to use the default ','. It is recommended to use '|+|' or other uncommon character combinations ','
--csv-null-value Representation of null values in CSV files "\N"
--escape-backslash Use backslash (\) to escape special characters in the export file true
--output-filename-template The filename templates represented in the format of golang template
Support the {{.DB}}, {{.Table}}, and {{.Index}} arguments
The three arguments represent the database name, table name, and chunk ID of the data file		 {{.DB}}.{{.Table}}.{{.Index}}
--status-addr Dumpling's service address, including the address for Prometheus to pull metrics and pprof debugging ":8281"
--tidb-mem-quota-query The memory limit of exporting SQL statements by a single line of Dumpling command, and the unit is byte. For v4.0.10 or later versions, if you do not set this parameter, TiDB uses the value of the mem-quota-query configuration item as the memory limit value by default. For versions earlier than v4.0.10, the parameter value defaults to 32 GB. 34359738368
--params Specifies the session variable for the connection of the database to be exported. The required format is "character_set_client=latin1,character_set_connection=latin1"
-c or --compress Compresses the CSV and SQL data and table structure files exported by Dumpling. It supports the following compression algorithms: gzip, snappy, and zstd. ""