Offline migration

Steps for an offline migration using YugabyteDB Voyager

The following page describes the steps to perform and verify a successful offline migration to YugabyteDB.

Migration workflow

Offline migration workflow

Phase	Step	Description
PREPARE	Install voyager	Voyager supports RHEL, CentOS, Ubuntu, and macOS. It can also be installed as airgapped and on Docker.
	Prepare source DB	Create a new database user with READ access to all the resources to be migrated.
	Prepare target DB	Deploy a YugabyteDB database and create a user with superuser privileges.
ASSESS	Assess Migration	Assess the migration complexity, and get schema changes, data distribution, and cluster sizing recommendations using the `yb-voyager assess-migration` command.
SCHEMA	Export schema	Convert the database schema to PostgreSQL format using the `yb-voyager export schema` command.
	Analyze schema	Generate a Schema Analysis Report using the `yb-voyager analyze-schema` command. The report suggests changes to the PostgreSQL schema to make it appropriate for YugabyteDB.
	Modify schema	Using the report recommendations, manually change the exported schema.
	Import schema	Import the modified schema to the target YugabyteDB database using the `yb-voyager import schema` command.
DATA	Export data	Dump the source database to the target machine (where yb-voyager is installed), using the `yb-voyager export data` command.
	Import data	Import the data to the target YugabyteDB database using the `yb-voyager import data` command.
	Finalize schema post data import	Restore NOT VALID constraints and refresh materialized views (if any) in the target YugabyteDB database using the `yb-voyager finalize-schema-post-data-import` command.
	Verify	Check if the offline migration is successful.
END	End migration	Clean up the migration information stored in the export directory and databases (source and target).

Before proceeding with migration, ensure that you have completed the following steps:

Install yb-voyager.
Review the guidelines for your migration.
Review data modeling strategies.
Prepare the source database.
Prepare the target database.

Prepare the source database

Create a new database user, and assign the necessary user permissions.

Create a database user and provide the user with READ access to all the resources which need to be migrated. Run the following commands in a psql session:

Create a new user named ybvoyager.

CREATE USER ybvoyager PASSWORD 'password';

Grant permissions for migration. Use the yb-voyager-pg-grant-migration-permissions.sql script (in /opt/yb-voyager/guardrails-scripts/ or, for brew, check in $(brew --cellar)/yb-voyager@<voyagerversion>/<voyagerversion>) to grant the required permissions as follows:

psql -h <host> \
     -d <database> \
     -U <username> \ # A superuser or a privileged user with enough permissions to grant privileges
     -v voyager_user='ybvoyager' \
     -v schema_list='<comma_separated_schema_list>' \
     -v is_live_migration=0 \
     -v is_live_migration_fall_back=0 \
     -f <path_to_the_script>

The ybvoyager user can now be used for migration.

If you want yb-voyager to connect to the source database over SSL, refer to SSL Connectivity.

Create a database user and provide the user with READ access to all the resources which need to be migrated. Replace <client_IP> from the following commands with an appropriate hostname in your setup.

Create a new user ybvoyager.

CREATE USER 'ybvoyager'@'<client_IP>' IDENTIFIED WITH  mysql_native_password BY 'Password#123';

Grant the global PROCESS permission.

GRANT PROCESS ON *.* TO 'ybvoyager'@'<client_IP>';

Grant the SELECT, SHOW VIEW, and TRIGGER permissions on the source database:

GRANT SELECT ON source_db_name.* TO 'ybvoyager'@'<client_IP>';
GRANT SHOW VIEW ON source_db_name.* TO 'ybvoyager'@'<client_IP>';
GRANT TRIGGER ON source_db_name.* TO 'ybvoyager'@'<client_IP>';

Note that if you want to accelerate data export, include the following grants additionally as follows:

For MYSQL

GRANT FLUSH_TABLES ON *.* TO 'ybvoyager'@'<client_IP>';
GRANT REPLICATION CLIENT ON *.* TO 'ybvoyager'@'<client_IP>';

For MYSQL RDS

GRANT FLUSH_TABLES ON *.* TO 'ybvoyager'@'<client_IP>';
GRANT REPLICATION CLIENT ON *.* TO 'ybvoyager'@'<client_IP>';
GRANT LOCK TABLES ON <source_db_name>.* TO 'ybvoyager'@'<client_IP>';

If you are running MySQL version 8.0.20 or later, grant the global SHOW_ROUTINE permission. For older versions, grant the global SELECT permission. These permissions are necessary to dump stored procedure/function definitions.
```
--For MySQL >= 8.0.20
GRANT SHOW_ROUTINE  ON *.* TO 'ybvoyager'@'<client_IP>';
```
```
--For older versions
GRANT SELECT ON *.* TO 'ybvoyager'@'<client_IP>';
```
The ybvoyager user can now be used for migration.

If you want yb-voyager to connect to the source database over SSL, refer to SSL Connectivity.

Create a role and a database user, and provide the user with READ access to all the resources which need to be migrated.

Create a role that has the privileges as listed in the following table:

Permission	Object type in the source schema
`SELECT`	VIEW, SEQUENCE, TABLE PARTITION, TABLE, SYNONYM, MATERIALIZED VIEW
`EXECUTE`	TYPE

Change the <SCHEMA_NAME> appropriately in the following snippets, and run the following steps as a privileged user.

CREATE ROLE <SCHEMA_NAME>_reader_role;

BEGIN
    FOR R IN (SELECT owner, object_name FROM all_objects WHERE owner=UPPER('<SCHEMA_NAME>') and object_type in ('VIEW','SEQUENCE','TABLE PARTITION','SYNONYM','MATERIALIZED VIEW'))
    LOOP
       EXECUTE IMMEDIATE 'grant select on '||R.owner||'."'||R.object_name||'" to <SCHEMA_NAME>_reader_role';
    END LOOP;
END;
/

BEGIN
    FOR R IN (SELECT owner, object_name FROM all_objects WHERE owner=UPPER('<SCHEMA_NAME>') and object_type ='TABLE' MINUS SELECT owner, table_name from all_nested_tables where owner = UPPER('<SCHEMA_NAME>'))
    LOOP
       EXECUTE IMMEDIATE 'grant select on '||R.owner||'."'||R.object_name||'" to  <SCHEMA_NAME>_reader_role';
    END LOOP;
END;
/

BEGIN
    FOR R IN (SELECT owner, object_name FROM all_objects WHERE owner=UPPER('<SCHEMA_NAME>') and object_type = 'TYPE')
    LOOP
       EXECUTE IMMEDIATE 'grant execute on '||R.owner||'."'||R.object_name||'" to <SCHEMA_NAME>_reader_role';
    END LOOP;
END;
/

GRANT SELECT_CATALOG_ROLE TO <SCHEMA_NAME>_reader_role;
GRANT SELECT ANY DICTIONARY TO <SCHEMA_NAME>_reader_role;
GRANT SELECT ON SYS.ARGUMENT$ TO <SCHEMA_NAME>_reader_role;

Create a user ybvoyager and grant CONNECT and <SCHEMA_NAME>_reader_role to the user:

CREATE USER ybvoyager IDENTIFIED BY password;
GRANT CONNECT TO ybvoyager;
GRANT <SCHEMA_NAME>_reader_role TO ybvoyager;

If you're using accelerated data export, run the additional grant as follows:

GRANT FLASHBACK ANY TABLE TO ybvoyager;

If you're using accelerated data export, the log_mode should be archivelog.
1. Check the value for log_mode using the following command for Oracle/Oracle RDS:
```
SELECT LOG_MODE FROM V$DATABASE;
```
2. If the log_mode value is NOARCHIVELOG, run the following commands:
  
  For Oracle
```
sqlplus /nolog
SQL>alter system set db_recovery_file_dest_size = 10G;
SQL>alter system set db_recovery_file_dest = '<oracle_path>/oradata/recovery_area' scope=spfile;
SQL> connect / as sysdba
SQL> Shutdown immediate
SQL> Startup mount
SQL> Alter database archivelog;
SQL> Alter database open;
```
  For Oracle RDS
  
  Note that the following step assumes you're using SQL*Plus or a compatible Oracle client that supports EXEC. If your client doesn't support EXEC, use the standard SQL CALL syntax instead.
```
exec rdsadmin.rdsadmin_util.set_configuration('archivelog retention hours',24);
```
3. Verify using archive log list.

If you want yb-voyager to connect to the source database over SSL, refer to SSL Connectivity. Note that you can use only one of the following arguments when connecting to your Oracle instance:

Configuration file source parameter	CLI Flag	Description
db-schema	--source-db-schema	Schema name of the source database.
oracle-db-sid	--oracle-db-sid	Oracle System Identifier you can use while exporting data from Oracle instances.
oracle-tns-alias	--oracle-tns-alias	TNS (Transparent Network Substrate) alias configured to establish a secure connection with the server.

Prepare the target database

Prepare your target YugabyteDB database cluster by creating a database, and a user for your cluster.

Create the target database

Create the target YugabyteDB database in your YugabyteDB cluster. The database name can be the same or different from the source database name. If the target YugabyteDB database name is not provided, yb-voyager assumes the target YugabyteDB database name to be yugabyte. If you do not want to import to the default yugabyte database, specify the name of the target YugabyteDB database using the --target-db-name argument of the yb-voyager import command.

CREATE DATABASE target_db_name;

If you intend to perform a migration assessment, note that the assessment provides recommendations on which tables in the source database to colocate. To ensure that you will be able to colocate tables, create your target database with colocation set to TRUE using the following command:

CREATE DATABASE target_db_name WITH COLOCATION = true;

Create a user

Create a user with SUPERUSER role.

For a local YugabyteDB cluster or YugabyteDB Anywhere, create a user and role with the superuser privileges using the following command:
```
CREATE USER ybvoyager SUPERUSER PASSWORD 'password';
```

For YugabyteDB Aeon, create a user with yb_superuser role using the following command:

CREATE USER ybvoyager PASSWORD 'password';
GRANT yb_superuser TO ybvoyager;

If you want yb-voyager to connect to the target YugabyteDB database over SSL, refer to SSL Connectivity.

Alternatively, if you want to proceed with migration without a superuser, refer to Import data without a superuser.

Create an export directory

yb-voyager keeps all of its migration state, including exported schema and data, in a local directory called the export directory.

Before starting migration, you should create the export directory on a file system that has enough space to keep the entire source database. Ideally, create this export directory inside a parent folder named after your migration for better organization. You need to provide the full path to the export directory in the export-dir parameter of your configuration file, or in the --export-dir flag when running yb-voyager commands.

mkdir -p $HOME/<migration-name>/export-dir

The export directory has the following sub-directories and files:

reports directory contains the generated Schema Analysis Report.
schema directory contains the source database schema translated to PostgreSQL. The schema is partitioned into smaller files by the schema object type such as tables, views, and so on.
data directory contains CSV (Comma Separated Values) files that are passed to the COPY command on the target YugabyteDB database.
metainfo and temp directories are used by yb-voyager for internal bookkeeping.
logs directory contains the log files for each command.

Set up a configuration file

You can use a configuration file to specify the parameters required when running Voyager commands (v2025.6.2 or later).

To get started, copy the offline-migration.yaml template configuration file from one of the following locations to the migration folder you created (for example, $HOME/my-migration/):

/opt/yb-voyager/config-templates/offline-migration.yaml

$(brew --cellar)/yb-voyager@<voyager-version>/<voyager-version>/config-templates/offline-migration.yaml

Replace <voyager-version> with your installed Voyager version, for example, 2025.5.2.

Set the export-dir, source, and target arguments in the configuration file:

# Replace the argument values with those applicable for your migration.

export-dir: <absolute-path-to-export-dir>

source:
  db-type: <source-db-type>
  db-host: <source-db-host>
  db-port: <source-db-port>
  db-name: <source-db-name>
  db-schema: <source-db-schema> # Not applicable for MySQL
  db-user: <source-db-user>
  db-password: <source-db-password> # Enclose the password in single quotes if it contains special characters.

target:
  db-host: <target-db-host>
  db-port: <target-db-port>
  db-name: <target-db-name>
  db-schema: <target-db-schema> # MySQL and Oracle only
  db-user: <target-db-username>
  db-password: <target-db-password> # Enclose the password in single quotes if it contains special characters.

Refer to the offline-migration.yaml template for more information on the available global, source, and target configuration parameters supported by Voyager.

Configure yugabyted UI

You can use yugabyted UI to view the migration assessment report, and to visualize and review the database migration workflow performed by YugabyteDB Voyager.

Configure the yugabyted UI as follows:

Start a local YugabyteDB cluster. Refer to the steps described in Use a local cluster. Skip this step if you already have a local YugabyteDB cluster as your target database.

To see the Voyager migration workflow details in the UI, set the following configuration parameters before starting the migration:

### Control plane type refers to the deployment type of YugabyteDB
control-plane-type: yugabyted

### YSQL connection string
### Provide the standard PostgreSQL connection parameters, including user name, host name, and port. For example, postgresql://yugabyte:yugabyte@127.0.0.1:5433
yugabyted-db-conn-string: postgresql://yugabyte:yugabyte@127.0.0.1:5433

Note

Don't include the dbname parameter in the connection string; the default yugabyte database is used to store the meta information for showing the migration in the yugabyted UI.

Assess migration

This step applies to PostgreSQL and Oracle migrations only.

Assess migration analyzes the source database, captures essential metadata, and generates a report with recommended migration strategies and cluster configurations for optimal performance with YugabyteDB.

You run assessments using the yb-voyager assess-migration command as follows:

Choose from one of the supported modes for conducting migration assessments, depending on your access to the source database as follows:
This mode requires direct connectivity to the source database from the client machine where voyager is installed. You initiate the assessment by executing the assess-migration command of yb-voyager. This command facilitates a live analysis by interacting directly with the source database, to gather metadata required for assessment. A sample command is as follows:
```
yb-voyager assess-migration --source-db-type postgresql \
    --source-db-host hostname --source-db-user ybvoyager \
    --source-db-password password --source-db-name dbname \
    --source-db-schema schema1,schema2 --export-dir /path/to/export/dir
```
If you are using a configuration file, use the following:
```
yb-voyager assess-migration --config-file <path-to-config-file>
```
PostgreSQL only. In situations where direct access to the source database is restricted, there is an alternative approach. Voyager includes packages with scripts for PostgreSQL at /etc/yb-voyager/gather-assessment-metadata.

You can perform the following steps with these scripts:
1. On a machine which has access to the source database, copy the scripts and install dependencies psql and pg_dump version 14 or later. Alternatively, you can install yb-voyager on the machine to automatically get the dependencies.
2. Run the yb-voyager-pg-gather-assessment-metadata.sh script by providing the source connection string, the schema names, path to a directory where metadata will be saved, and an optional argument of an interval to capture the IOPS metadata of the source (in seconds with a default value of 120). For example:
  /path/to/yb-voyager-pg-gather-assessment-metadata.sh 'postgresql://ybvoyager@host:port/dbname' 'schema1|schema2' '/path/to/assessment_metadata_dir' '60'
3. Copy the metadata directory to the client machine on which voyager is installed, and run the assess-migration command by specifying the path to the metadata directory as follows:
  yb-voyager assess-migration --source-db-type postgresql \ --assessment-metadata-dir /path/to/assessment_metadata_dir --export-dir /path/to/export/dir
  If you are using a configuration file, use the following:
  yb-voyager assess-migration --config-file <path-to-config-file>
The output is a migration assessment report, and its path is printed on the console. To view the assessment report, navigate to the Migrations tab in the yugabyted UI at http://127.0.0.1:15433 to see the available migrations.

Important
For the most accurate migration assessment, the source database must be actively handling its typical workloads at the time the metadata is gathered. This ensures that the recommendations for sharding strategies and cluster sizing are well-aligned with the database's real-world performance and operational needs.
Resize your target YugabyteDB cluster in Enhanced PostgreSQL Compatibility Mode, based on the sizing recommendations in the assessment report.

If you are using YugabyteDB Anywhere, enable compatibility mode by setting the More > Edit Postgres Compatibility option.
If the assessment recommended creating some tables as colocated, check that your target YugabyteDB database is colocated in ysqlsh using the following command:
```
select yb_is_database_colocated();
```

Refer to Migration assessment for more information.

Migrate your database to YugabyteDB

Proceed with schema and data migration using the following steps:

Export and analyze schema

To begin, export the schema from the source database. Once exported, analyze the schema and apply any necessary manual changes.

Export schema

Technical Advisory

TA-2968 : Import schema fails on all Voyager installs done after August 14, 2025. Impacts v1.1 to v2025.8.1.

The yb-voyager export schema command extracts the schema from the source database, converts it into PostgreSQL format (if the source database is Oracle or MySQL), and dumps the SQL DDL files in the EXPORT_DIR/schema/* directories.

For PostgreSQL migrations:

Recommended schema optimizations from the assess migration report are applied to ensure YugabyteDB compatibility and optimal performance.
A Schema Optimization Report, with details and an explanation of every change, is generated for your review.

For MySQL migrations:

YugabyteDB Voyager renames the indexes to avoid naming conflicts. MySQL allows two or more indexes to have the same name in the same database, provided they are for different tables. Like PostgreSQL, YugabyteDB does not support duplicate index names in the same schema. To avoid index name conflicts during export schema, Voyager prefixes each index name with the associated table name.

You specify the schema(s) to migrate from the source database using the db-schema parameter (configuration file), or --source-db-schema flag (CLI).

For MySQL, currently this argument is not applicable.
For PostgreSQL, this argument can take one or more schema names separated by comma.
For Oracle, this argument can take only one schema name and you can migrate only one schema at a time.

Run the command as follows:

yb-voyager export schema --config-file <path-to-config-file>

You can specify additional export schema parameters in the export-schema section of the configuration file. For more details, refer to the offline-migration.yaml template.

# Replace the argument values with those applicable for your migration.
yb-voyager export schema --export-dir <EXPORT_DIR> \
        --source-db-type <SOURCE_DB_TYPE> \
        --source-db-host <SOURCE_DB_HOST> \
        --source-db-user <SOURCE_DB_USER> \
        --source-db-password <SOURCE_DB_PASSWORD> \ # Enclose the password in single quotes if it contains special characters.
        --source-db-name <SOURCE_DB_NAME> \
        --source-db-schema <SOURCE_DB_SCHEMA> # Not applicable for MySQL

Refer to export schema for more information on the use of the command.

Analyze schema

Technical Advisory

TA-2968 : Import schema fails on all Voyager installs done after August 14, 2025. Impacts v1.1 to v2025.8.1.

The schema exported in the previous step may not yet be suitable for importing into YugabyteDB. Even though YugabyteDB is PostgreSQL compatible, given its distributed nature, you may need to make minor manual changes to the schema.

The yb-voyager analyze-schema command analyses the PostgreSQL schema dumped in the export schema step, and prepares a report that lists the DDL statements which need manual changes.

By default, the report is output in HTML and JSON format. You can optionally change the format for the output (options are html, txt, json, or xml) using the output-format parameter (configuration file) or flag (CLI).

Run the command as follows:

yb-voyager analyze-schema --config-file <path-to-config-file>

You can specify additional analyze-schema parameters in the analyze-schema section of the configuration file. For more details, refer to the offline-migration.yaml template.

# Replace the argument values with those applicable for your migration.
yb-voyager analyze-schema --export-dir <EXPORT_DIR> --output-format <FORMAT>

Refer to analyze schema for more information on the use of the command.

Manually edit the schema

Fix all the issues listed in the generated schema analysis report by manually editing the SQL DDL files from the EXPORT_DIR/schema/*.

After making the manual changes, re-run the yb-voyager analyze-schema command. This generates a fresh report using your changes. Repeat these steps until the generated report contains no issues.

To learn more about modelling strategies using YugabyteDB, refer to Data modeling.

Manual schema changes

Include the primary key definition in the CREATE TABLE statement. Primary Key cannot be added to a partitioned table using the ALTER TABLE statement.

Refer to the Manual review guideline for a detailed list of limitations and suggested workarounds associated with the source databases when migrating to YugabyteDB Voyager.

Import schema

Technical Advisory

TA-2968 : Import schema fails on all Voyager installs done after August 14, 2025. Impacts v1.1 to v2025.8.1.

Import the schema using the yb-voyager import schema command.

The db-schema key inside the target section parameters (configuration file), or the --target-db-schema flag (CLI), is used to specify the schema in the target YugabyteDB database where the source schema will be imported and is applicable only for MySQL and Oracle. yb-voyager imports the source database into the public schema of the target YugabyteDB database. By specifying this argument during import, you can instruct yb-voyager to create a non-public schema and use it for the schema/data import.

Run the command as follows:

yb-voyager import schema --config-file <path-to-config-file>

You can specify additional import schema parameters in the import-schema section of the configuration file. For more details, refer to the [offline-migration.yaml](https://github.com/yugabyte/yb-voyager/blob/{{< yb-voyager-release >}}/yb-voyager/config-templates/offline-migration.yaml) template.

# Replace the argument values with those applicable for your migration.
yb-voyager import schema --export-dir <EXPORT_DIR> \
        --target-db-host <TARGET_DB_HOST> \
        --target-db-user <TARGET_DB_USER> \
        --target-db-password <TARGET_DB_PASSWORD> \ # Enclose the password in single quotes if it contains special characters.
        --target-db-name <TARGET_DB_NAME> \
        --target-db-schema <TARGET_DB_SCHEMA> # MySQL and Oracle only

Refer to import schema for more information on the use of the command.

NOT VALID constraints are not imported

Currently, import schema does not import NOT VALID constraints exported from source, because this could lead to constraint violation errors during the import if the source contains the data that is violating the constraint.

Voyager will add these constraints back during Finalize schema post data import.

yb-voyager applies the DDL SQL files located in the schema sub-directory of the export directory to the target YugabyteDB database. If yb-voyager terminates before it imports the entire schema, you can rerun it by adding the ignore-exist argument (configuration file), or using the --ignore-exist flag (CLI).

Export data

You can export the source data using the yb-voyager export data command. This command dumps the source database data into CSV files in the EXPORT_DIR/data directory.

Run the command as follows:

yb-voyager export data --config-file <path-to-config-file>

You can specify additional export data parameters in the export-data section of the configuration file. For more details, refer to the [offline-migration.yaml](https://github.com/yugabyte/yb-voyager/blob/{{< yb-voyager-release >}}/yb-voyager/config-templates/offline-migration.yaml) template.

# Replace the argument values with those applicable for your migration.
yb-voyager export data --export-dir <EXPORT_DIR> \
        --source-db-type <SOURCE_DB_TYPE> \
        --source-db-host <SOURCE_DB_HOST> \
        --source-db-user <SOURCE_DB_USER> \
        --source-db-password <SOURCE_DB_PASSWORD> \ # Enclose the password in single quotes if it contains special characters.
        --source-db-name <SOURCE_DB_NAME> \
        --source-db-schema <SOURCE_DB_SCHEMA> # Not applicable for MySQL

PostgreSQL and parallel jobs

For PostgreSQL, make sure that no other processes are running on the source database that can try to take locks; with more than one parallel job, Voyager will not be able to take locks to dump the data.

Note that the db-schema argument (configuration file) or the --source-db-schema flag (CLI) is required for PostgreSQL and Oracle, and is not applicable for MySQL.

The options passed to the command are similar to the yb-voyager export schema command. To export only a subset of tables, provide a comma-separated list of table names using the table-list argument (configuration file), or pass it via the --table-list flag (CLI).

Refer to export data for more information.

Sequence migration considerations

Sequence migration consists of two steps: sequence creation and setting resume value (resume value refers to the NEXTVAL of a sequence on a source database). A sequence object is generated during export schema and the resume values for sequences are generated during export data. These resume values are then set on the target YugabyteDB database just after the data is imported for all tables.

Note that there are some special cases involving sequences such as the following:

In MySQL, auto-increment column is migrated to YugabyteDB as a normal column with a sequence attached to it.
For PostgreSQL, only the sequences attached to or owned by the migrating tables are restored during the migration.

Migrating source databases with large row sizes

If a table's row size on the source database is too large, and exceeds the default RPC message size, import data will fail with the error ERROR: Sending too long RPC message... So, you need to migrate those tables separately after removing the large rows.

Export data status

To get an overall progress of the export data operation, you can run the yb-voyager export data status command. You specify the <EXPORT_DIR> to push data in using export-dir parameter (configuration file), or --export-dir flag (CLI).

Run the command as follows:

yb-voyager export data status --config-file <path-to-config-file>

You can specify additional export data status parameters in the export-data-status section of the configuration file. For more details, refer to the [offline-migration.yaml](https://github.com/yugabyte/yb-voyager/blob/{{< yb-voyager-release >}}/yb-voyager/config-templates/offline-migration.yaml) template.

yb-voyager export data status --export-dir <EXPORT_DIR>` command.

Refer to export data status for more information.

Accelerate data export for MySQL and Oracle

For MySQL and Oracle, you can optionally speed up data export by setting the argument beta-fast-data-export: 1 in the export-data section of the configuration file when you run export data. Alternatively, you can set the environment variable BETA_FAST_DATA_EXPORT=1.

Consider the following caveats before using the feature:

You need to perform additional steps when you prepare the source database.
Some data types are unsupported. For a detailed list, refer to datatype mappings.
The parallel-jobs argument (configuration file) or --parallel-jobs flag (CLI), which specifies the number of tables to be exported in parallel from the source database, will have no effect.
In MySQL RDS, writes are not allowed during the data export process.
Sequences that are not associated with any column or attached to columns of non-integer types are not supported for resuming value generation.

Import data

After you have successfully exported the source data and imported the schema in the target YugabyteDB database, you can import the data using the yb-voyager import data command with required arguments.

Run the command as follows:

yb-voyager import data --config-file <path-to-config-file>

You can specify additional import data parameters in the import-data section of the configuration file. For more details, refer to the [offline-migration.yaml](https://github.com/yugabyte/yb-voyager/blob/{{< yb-voyager-release >}}/yb-voyager/config-templates/offline-migration.yaml) template.

# Replace the argument values with those applicable for your migration.
yb-voyager import data --export-dir <EXPORT_DIR> \
        --target-db-host <TARGET_DB_HOST> \
        --target-db-user <TARGET_DB_USER> \
        --target-db-password <TARGET_DB_PASSWORD> \ # Enclose the password in single quotes if it contains special characters.
        --target-db-name <TARGET_DB_NAME> \
        --target-db-schema <TARGET_DB_SCHEMA> \ # MySQL and Oracle only.

By default, yb-voyager imports data in parallel using multiple connections, and adapts the parallelism based on the resource usage of the cluster. Refer to Techniques to improve performance for more details on tuning performance.

Refer to import data for more information.

yb-voyager splits the data dump files (from the $EXPORT_DIR/data directory) into smaller batches. yb-voyager concurrently ingests the batches such that all nodes of the target YugabyteDB database cluster are used. This phase is designed to be restartable if yb-voyager terminates while the data import is in progress. After restarting, the data import resumes from its current state.

Importing large datasets

When importing a very large database, run the import data command in a screen session, so that the import is not terminated when the terminal session stops.

If the yb-voyager import data command terminates before completing the data ingestion, you can re-run it with the same arguments and the command will resume the data import operation.

Migrating source databases with large row sizes

When exporting data using the beta-fast-data-export configuration parameter or the BETA_FAST_DATA_EXPORT environment variable, the import data process has a default row size limit of 32MB. If a row exceeds this limit but is smaller than the batch-size * max-row-size, you can increase the limit for the import data process by setting the following configuration parameter in import data to handle such rows:

import-data:
  csv-reader-max-buffer-size-bytes: <MAX_ROW_SIZE_IN_BYTES>

Alternatively, you can export the following environment variable:

export CSV_READER_MAX_BUFFER_SIZE_BYTES = <MAX_ROW_SIZE_IN_BYTES>

Import data status

To get an overall progress of the import data operation, you can run the yb-voyager import data status command. You specify the <EXPORT_DIR> to push data in using export-dir parameter (configuration file), or --export-dir flag (CLI).

Run the command as follows:

yb-voyager import data status --config-file <path-to-config-file>

You can specify additional import data status parameters in the import-data-status section of the configuration file. For more details, refer to the [offline-migration.yaml](https://github.com/yugabyte/yb-voyager/blob/{{< yb-voyager-release >}}/yb-voyager/config-templates/offline-migration.yaml) template.

yb-voyager import data status --export-dir <EXPORT_DIR>` command.

Refer to import data status for more information.

Finalize schema post data import

If there are any NOT VALID constraints on the source, create them after the import data command is completed by using the finalize-schema-post-data-import command. If there are Materialized views in the target YugabyteDB database, you can refresh them by setting the refresh-mviews parameter in the finalize-schema-post-data-import (configuration file) or use --refresh-mviews flag (CLI) with the value true. Run the command as follows:

yb-voyager finalize-schema-post-data-import --config-file <path-to-config-file>

# Replace the argument values with those applicable for your migration.
yb-voyager finalize-schema-post-data-import --export-dir <EXPORT_DIR> \
       --target-db-host <TARGET_DB_HOST> \
       --target-db-user <TARGET_DB_USER> \
       --target-db-password <TARGET_DB_PASSWORD> \ # Enclose the password in single quotes if it contains special characters.
       --target-db-name <TARGET_DB_NAME> \
       --target-db-schema <TARGET_DB_SCHEMA> \ # MySQL and Oracle only

Refer to finalize-schema-post-data-import for more information.

Note

The import schema --post-snapshot-import command is deprecated. Use finalize-schema-post-data-import instead.

Verify migration

After the schema and data import is complete, manually run validation queries on both the source and target YugabyteDB database to ensure that the data is correctly migrated. For example, you can validate the databases by running queries to check the row count of each table.

Caveat associated with rows reported by import data status

Suppose you have the following scenario:

The import data or import data file command fails.
To resolve this issue, you delete some of the rows from the split files.
After retrying, the import data command completes successfully.

In this scenario, the import data status command reports an incorrect imported row count, because it doesn't take into account the deleted rows.

For more details, refer to GitHub issue #360.

End migration

To complete the migration, you need to clean up the export directory (export-dir) and Voyager state (Voyager-related metadata) stored in the target YugabyteDB database.

The yb-voyager end migration command performs the cleanup, and backs up the schema, data, migration reports, and log files by providing the backup related arguments.

Run the command as follows:

Specify the following parameters in the end-migration section of the configuration file:

...
end-migration:
  backup-schema-files: <true, false, yes, no, 1, 0>
  backup-data-files: <true, false, yes, no, 1, 0>
  save-migration-reports: <true, false, yes, no, 1, 0>
  backup-log-files: <true, false, yes, no, 1, 0>
  # Set optional argument to store a back up of any of the above  arguments.
  backup-dir: <BACKUP_DIR>
...

Run the command:

yb-voyager end migration --config-file <path-to-config-file>

# Replace the argument values with those applicable for your migration.
yb-voyager end migration --export-dir <EXPORT_DIR> \
        --backup-log-files <true, false, yes, no, 1, 0> \
        --backup-data-files <true, false, yes, no, 1, 0> \
        --backup-schema-files <true, false, yes, no, 1, 0> \
        --save-migration-reports <true, false, yes, no, 1, 0> \
        # Set optional argument to store a back up of any of the above arguments.
        --backup-dir <BACKUP_DIR>

After you run end migration, you will not be able to continue further.

If you want to back up the schema, data, log files, and the migration reports (analyze-schema report, export data status output, or import data status output) for future reference, use the backup-dir argument (configuration file) or --backup-dir flag (CLI), and provide the path of the directory where you want to save the backup content (based on what you choose to back up).

Refer to end migration for more information.

Delete the ybvoyager user (Optional)

After migration, all the migrated objects (tables, views, and so on) are owned by the ybvoyager user. Transfer the ownership of the objects to some other user (for example, yugabyte) and then delete the ybvoyager user. For example, do the following:

REASSIGN OWNED BY ybvoyager TO yugabyte;
DROP OWNED BY ybvoyager;
DROP USER ybvoyager;