Project: YugabyteDB (App Definition and Development / Database)
File: live-migrate.md

title: Steps to perform live migration of your database using YugabyteDB Voyager headerTitle: Live migration linkTitle: Live migration headcontent: Steps for a live migration using YugabyteDB Voyager description: Run the steps to ensure a successful live migration using YugabyteDB Voyager. menu: preview_yugabyte-voyager: identifier: migrate-live parent: migration-types weight: 103 techPreview: /preview/releases/versioning/#feature-availability type: docs The following instructions describe the steps to perform and verify a successful live migration to YugabyteDB, including changes that continuously occur on the source. The following workflows illustrate how you can perform data migration including changes happening on the source simultaneously. With the export data command, you can first export a snapshot and then start continuously capturing changes occurring on the source to an event queue on the disk. Using the import data command, you similarly import the snapshot first, and then continuously apply the exported change events on the target. Eventually, the migration process reaches a steady state where you can . You can stop your applications from pointing to your source database, let all the remaining changes be applied on the target YugabyteDB database, and then restart your applications pointing to YugabyteDB. The following illustration describes how the data export and import operations are simultaneously handled by YugabyteDB Voyager. The following illustration shows the steps in a live migration using YugabyteDB Voyager. | Phase | Step | Description | | :- | : | :| | PREPARE | | yb-voyager supports RHEL, CentOS, Ubuntu, and macOS, as well as airgapped and Docker-based installations. | | | | Create a new database user with READ access to all the resources to be migrated. | | | | Deploy a YugabyteDB database and create a user with necessary privileges. | | SCHEMA | | Convert the database schema to PostgreSQL format using the `yb-voyager export schema` command. | | | | Generate a Schema&nbsp;Analysis&nbsp;Report using the `yb-voyager analyze-schema` command. The report suggests changes to the PostgreSQL schema to make it appropriate for YugabyteDB. | | | | Using the report recommendations, manually change the exported schema. | | | | Import the modified schema to the target YugabyteDB database using the `yb-voyager import schema` command. | | LIVE&nbsp;MIGRATION | Start | Start the phases: export data first, followed by import data and archive changes simultaneously. | | | | The export data command first exports a snapshot and then starts continuously capturing changes from the source.| | | | The import data command first imports the snapshot, and then continuously applies the exported change events on the target. | | | | After the snapshot import is complete, import indexes and triggers to the target YugabyteDB database using the `yb-voyager import schema` command with an additional `--post-snapshot-import` flag. | | | | Continuously archive migration changes to limit disk utilization. | | CUTOVER | | Perform a cutover (stop streaming changes) when the migration process reaches a steady state where you can stop your applications from pointing to your source database, allow all the remaining changes to be applied on the target YugabyteDB database, and then restart your applications pointing to YugabyteDB. | | | | Monitor the wait status using the command. | | | | Check if the live migration is successful. | | END | | Clean up the migration information stored in export directory and databases (source and target). | Before proceeding with migration, ensure that you have completed the following steps: . Review the . Review strategies. . . Create a new database user, and assign the necessary user

<ul class="nav nav-tabs-alt nav-tabs-yb custom-tabs"> <li> <a href="#oracle" class="nav-link active" id="oracle-tab" data-toggle="tab" role="tab" aria-controls="oracle" aria-selected="true"> <i class="icon-oracle" aria-hidden="true"></i> Oracle </a> </li> <li > <a href="#pg" class="nav-link" id="pg-tab" data-toggle="tab" role="tab" aria-controls="pg" aria-selected="false"> <i class="icon-postgres" aria-hidden="true"></i> PostgreSQL </a> </li> </ul> <div class="tab-content"> <div id="oracle" class="tab-pane fade show active" role="tabpanel" aria-labelledby="oracle-tab"> {{< tabpane text=true >}} {{% tab header="Standalone Oracle Container Database" %}} Ensure that your database log_mode is `archivelog` as follows: ```sql SELECT LOG_MODE FROM V$DATABASE; ``` ```output LOG_MODE ARCHIVELOG ``` If log_mode is NOARCHIVELOG (that is, not enabled), run the following command: ```sql sqlplus /nolog SQL>alter system set dbrecoveryfiledestsize = 10G; SQL>alter system set dbrecoveryfiledest = '<oraclepath>/oradata/recovery_area' scope=spfile; SQL> connect / as sysdba SQL> Shutdown immediate SQL> Startup mount SQL> Alter database archivelog; SQL> Alter database open; ``` Create the tablespaces as follows: Connect to Pluggable database (PDB) as sysdba and run the following command: ```sql CREATE TABLESPACE logminertbs DATAFILE '/opt/oracle/oradata/ORCLCDB/ORCLPDB1/logminertbs.dbf' SIZE 25M REUSE AUTOEXTEND ON MAXSIZE UNLIMITED; ``` Connect to Container database (CDB) as sysdba and run the following command: ```sql CREATE TABLESPACE logminertbs DATAFILE '/opt/oracle/oradata/ORCLCDB/logminertbs.dbf' SIZE 25M REUSE AUTOEXTEND ON MAXSIZE UNLIMITED; ``` Run the following commands from CDB as sysdba: ```sql CREATE USER c##ybvoyager IDENTIFIED BY password DEFAULT TABLESPACE logminer_tbs QUOTA UNLIMITED ON logminer_tbs CONTAINER=ALL; GRANT CREATE SESSION TO c##ybvoyager CONTAINER=ALL; GRANT SET CONTAINER TO c##ybvoyager CONTAINER=ALL; GRANT SELECT ON V_$DATABASE to c##ybvoyager CONTAINER=ALL; GRANT FLASHBACK ANY TABLE TO c##ybvoyager CONTAINER=ALL; GRANT SELECT ANY TABLE TO c##ybvoyager CONTAINER=ALL; GRANT SELECTCATALOGROLE TO c##ybvoyager CONTAINER=ALL; GRANT EXECUTECATALOGROLE TO c##ybvoyager CONTAINER=ALL; GRANT SELECT ANY TRANSACTION TO c##ybvoyager CONTAINER=ALL; GRANT LOGMINING TO c##ybvoyager CONTAINER=ALL; GRANT CREATE TABLE TO c##ybvoyager CONTAINER=ALL; GRANT LOCK ANY TABLE TO c##ybvoyager CONTAINER=ALL; GRANT CREATE SEQUENCE TO c##ybvoyager CONTAINER=ALL; GRANT EXECUTE ON DBMS_LOGMNR TO c##ybvoyager CONTAINER=ALL; GRANT EXECUTE ON DBMSLOGMNRD TO c##ybvoyager CONTAINER=ALL; GRANT SELECT ON V_$LOG TO c##ybvoyager CONTAINER=ALL; GRANT SELECT ON V$LOGHISTORY TO c##ybvoyager CONTAINER=ALL; GRANT SELECT ON V$LOGMNRLOGS TO c##ybvoyager CONTAINER=ALL; GRANT SELECT ON V$LOGMNRCONTENTS TO c##ybvoyager CONTAINER=ALL; GRANT SELECT ON V$LOGMNRPARAMETERS TO c##ybvoyager CONTAINER=ALL; GRANT SELECT ON V_$LOGFILE TO c##ybvoyager CONTAINER=ALL; GRANT SELECT ON V$ARCHIVEDLOG TO c##ybvoyager CONTAINER=ALL; GRANT SELECT ON V$ARCHIVEDEST_STATUS TO c##ybvoyager CONTAINER=ALL; GRANT SELECT ON V_$TRANSACTION TO c##ybvoyager CONTAINER=ALL; GRANT SELECT ON V_$MYSTAT TO c##ybvoyager CONTAINER=ALL; GRANT SELECT ON V_$STATNAME TO c##ybvoyager CONTAINER=ALL; ``` Enable supplemental logging in the database as follows: ```sql ALTER DATABASE ADD SUPPLEMENTAL LOG DATA; ALTER DATABASE ADD SUPPLEMENTAL LOG DATA (ALL) COLUMNS; ``` {{% /tab %}} {{% tab header="RDS Oracle" %}} Ensure that your database log_mode is `archivelog` as follows: ```sql SELECT LOG_MODE FROM V$DATABASE; ``` ```output LOG_MODE ARCHIVELOG ``` If log_mode is NOARCHIVELOG (that is, not enabled), run the following command: ```sql exec rdsadmin.rdsadminutil.setconfiguration('archivelog retention hours',24); ``` Connect to your database as an admin user, and create the tablespaces as follows: ```sql CREATE TABLESPACE logminer_tbs DATAFILE SIZE 25M AUTOEXTEND ON MAXSIZE UNLIMITED; ``` Run the following commands connected to the admin or privileged user: ```sql CREATE USER ybvoyager IDENTIFIED BY password DEFAULT TABLESPACE logminer_tbs QUOTA UNLIMITED ON logminer_tbs; GRANT CREATE SESSION TO YBVOYAGER; begin rdsadmin.rdsadminutil.grantsys_object( pobjname => 'V_$DATABASE', p_grantee => 'YBVOYAGER', p_privilege => 'SELECT'); end; / GRANT FLASHBACK ANY TABLE TO YBVOYAGER; GRANT SELECT ANY TABLE TO YBVOYAGER; GRANT SELECTCATALOGROLE TO YBVOYAGER; GRANT EXECUTECATALOGROLE TO YBVOYAGER; GRANT SELECT ANY TRANSACTION TO YBVOYAGER; GRANT LOGMINING TO YBVOYAGER; GRANT CREATE TABLE TO YBVOYAGER; GRANT LOCK ANY TABLE TO YBVOYAGER; GRANT CREATE SEQUENCE TO YBVOYAGER; begin rdsadmin.rdsadminutil.grantsys_object( pobjname => 'DBMS_LOGMNR', p_grantee => 'YBVOYAGER', p_privilege => 'EXECUTE', pgrantoption => true); end; / begin rdsadmin.rdsadminutil.grantsys_object( pobjname => 'DBMSLOGMNRD', p_grantee => 'YBVOYAGER', p_privilege => 'EXECUTE', pgrantoption => true); end; / begin

pobjname => 'V_$LOG', p_grantee => 'YBVOYAGER', p_privilege => 'SELECT'); end; / begin rdsadmin.rdsadminutil.grantsys_object( pobjname => 'V$LOGHISTORY', p_grantee => 'YBVOYAGER', p_privilege => 'SELECT'); end; / begin rdsadmin.rdsadminutil.grantsys_object( pobjname => 'V$LOGMNRLOGS', p_grantee => 'YBVOYAGER', p_privilege => 'SELECT'); end; / begin rdsadmin.rdsadminutil.grantsys_object( pobjname => 'V$LOGMNRCONTENTS', p_grantee => 'YBVOYAGER', p_privilege => 'SELECT'); end; / begin rdsadmin.rdsadminutil.grantsys_object( pobjname => 'V$LOGMNRPARAMETERS', p_grantee => 'YBVOYAGER', p_privilege => 'SELECT'); end; / begin rdsadmin.rdsadminutil.grantsys_object( pobjname => 'V_$LOGFILE', p_grantee => 'YBVOYAGER', p_privilege => 'SELECT'); end; / begin rdsadmin.rdsadminutil.grantsys_object( pobjname => 'V$ARCHIVEDLOG', p_grantee => 'YBVOYAGER', p_privilege => 'SELECT'); end; / begin rdsadmin.rdsadminutil.grantsys_object( pobjname => 'V$ARCHIVEDEST_STATUS', p_grantee => 'YBVOYAGER', p_privilege => 'SELECT'); end; / begin rdsadmin.rdsadminutil.grantsys_object( pobjname => 'V_$TRANSACTION', p_grantee => 'YBVOYAGER', p_privilege => 'SELECT'); end; / begin rdsadmin.rdsadminutil.grantsys_object( pobjname => 'V_$MYSTAT', p_grantee => 'YBVOYAGER', p_privilege => 'SELECT'); end; / begin rdsadmin.rdsadminutil.grantsys_object( pobjname => 'V_$STATNAME', p_grantee => 'YBVOYAGER', p_privilege => 'SELECT'); end; / ``` Enable supplemental logging in the database as follows: ```sql exec rdsadmin.rdsadminutil.altersupplemental_logging('ADD'); begin rdsadmin.rdsadminutil.altersupplemental_logging( p_action => 'ADD', p_type => 'ALL'); end; / ``` {{% /tab %}} {{< /tabpane >}} </div> <div id="pg" class="tab-pane fade" role="tabpanel" aria-labelledby="pg-tab"> {{< tabpane text=true >}} {{% tab header="Standalone PostgreSQL" %}} ybvoyager requires `wallevel` to be logical. You can check this using following the steps: Run the command `SHOW wal_level` on the database to check the value. If the value is anything other than logical, run the command `SHOW config_file` to know the path of your configuration file. Modify the configuration file by uncommenting the parameter `wal_level` and set the value to logical. Restart PostgreSQL. Check that the replica identity is "FULL" for all tables on the database. Check the replica identity using the following query: ```sql SELECT n.nspname, relname, relreplident FROM pgclass c JOIN pgnamespace n on c.relnamespace = n.oid WHERE n.nspname in (<SCHEMA_LIST>) and relkind = 'r'; SCHEMALIST used is a comma-separated list of schemas, for example, SCHEMALIST 'abc','public', 'xyz'. ``` Change the replica identity of all tables if the tables have an identity other than FULL (`f`), using the following query: ```sql DO $$ DECLARE r Record; BEGIN FOR r IN (SELECT tableschema, '"' || tablename || '"' as tname FROM informationschema.tables WHERE tableschema IN (<SCHEMALIST>) AND table_type = 'BASE TABLE') LOOP EXECUTE 'ALTER TABLE ' || r.tableschema || '.' || r.tname || ' REPLICA IDENTITY FULL'; END LOOP; END $$; SCHEMALIST used is a comma-separated list of schemas, for example, SCHEMALIST 'abc','public', 'xyz'. ``` Create user `ybvoyager` for the migration using the following command: ```sql CREATE USER ybvoyager PASSWORD 'password' REPLICATION; ``` Switch to the database that you want to migrate as follows: ```sql \c <database_name> ``` Grant the `USAGE` permission to the `ybvoyager` user on all schemas of the database as follows: ```sql SELECT 'GRANT USAGE ON SCHEMA ' || schemaname || ' TO ybvoyager;' FROM informationschema.schemata; \gexec ``` The preceding `SELECT` statement generates a list of `GRANT USAGE` statements which are then executed by `psql` because of the `\gexec` switch. The `\gexec` switch works for PostgreSQL v9.6 and later. For earlier versions, you'll have to manually execute the `GRANT USAGE ON SCHEMA schema_name TO ybvoyager` statement, for each schema in the source PostgreSQL database. Grant `SELECT` permission on all the tables and sequences as follows: ```sql SELECT 'GRANT SELECT ON ALL TABLES IN SCHEMA ' || schemaname || ' TO ybvoyager;' FROM informationschema.schemata; \gexec SELECT 'GRANT SELECT ON ALL SEQUENCES IN SCHEMA ' || schemaname || ' TO ybvoyager;' FROM

\gexec ``` Create a replication group as follows: ```sql CREATE ROLE replication_group; ``` Add the original owner of the table to the group as follows: ```sql GRANT replicationgroup TO <originalowner>; ``` Add the user `ybvoyager` to the replication group as follows: ```sql GRANT replication_group TO ybvoyager; ``` Transfer ownership of the tables to the role `replication_group` as follows: ```sql DO $$ DECLARE r Record; BEGIN FOR r IN (SELECT tableschema, '"' || tablename || '"' as tname FROM informationschema.tables WHERE tableschema IN (<SCHEMALIST>)) LOOP EXECUTE 'ALTER TABLE ' || r.tableschema || '.' || r.tname || ' OWNER TO replication_group'; END LOOP; END $$; SCHEMALIST used is a comma-separated list of schemas, for example, SCHEMALIST 'abc','public', 'xyz'. ``` Grant `CREATE` privilege on the source database to `ybvoyager` as follows: ```sql GRANT CREATE ON DATABASE <database_name> TO ybvoyager; --required to create a publication. ``` The `ybvoyager` user can now be used for migration. {{% /tab %}} {{% tab header="RDS PostgreSQL" %}} ybvoyager requires `wallevel` to be logical. This is controlled by a database parameter `rds.logical_replication` which needs to be set to 1. You can check this using following the steps: Run the command `SHOW rds.logical_replication` on the database to check whether the parameter is set. If the parameter is not set, you can change the parameter value to 1 from the RDS console of the database; navigate to Configuration > Parameter group > `rds.logical_replication`. If the `rds.logical_replication` errors out (after the change), create a new parameter group with the value as 1, and assign it to the database instance from the Modify option on the RDS console. Restart RDS. Check that the replica identity is "FULL" for all tables on the database. Check the replica identity using the following query: ```sql SELECT n.nspname, relname, relreplident FROM pgclass c JOIN pgnamespace n on c.relnamespace = n.oid WHERE n.nspname in (<SCHEMA_LIST>) and relkind = 'r'; SCHEMALIST used is a comma-separated list of schemas, for example, SCHEMALIST 'abc','public', 'xyz'. ``` Change the replica identity of all tables if the tables have an identity other than FULL (`f`), using the following query: ```sql DO $$ DECLARE r Record; BEGIN FOR r IN (SELECT tableschema, '"' || tablename || '"' as tname FROM informationschema.tables WHERE tableschema IN (<SCHEMALIST>) AND table_type = 'BASE TABLE') LOOP EXECUTE 'ALTER TABLE ' || r.tableschema || '.' || r.tname || ' REPLICA IDENTITY FULL'; END LOOP; END $$; SCHEMALIST used is a comma-separated list of schemas, for example, SCHEMALIST 'abc','public', 'xyz'. ``` Create user `ybvoyager` for the migration using the following command: ```sql CREATE USER ybvoyager PASSWORD 'password'; GRANT rds_replication to ybvoyager; ``` Switch to the database that you want to migrate as follows: ```sql \c <database_name> ``` Grant the `USAGE` permission to the `ybvoyager` user on all schemas of the database as follows: ```sql SELECT 'GRANT USAGE ON SCHEMA ' || schemaname || ' TO ybvoyager;' FROM informationschema.schemata; \gexec ``` The preceding `SELECT` statement generates a list of `GRANT USAGE` statements which are then executed by `psql` because of the `\gexec` switch. The `\gexec` switch works for PostgreSQL v9.6 and later. For earlier versions, you'll have to manually execute the `GRANT USAGE ON SCHEMA schema_name TO ybvoyager` statement, for each schema in the source PostgreSQL database. Grant `SELECT` permission on all the tables and sequences as follows: ```sql SELECT 'GRANT SELECT ON ALL TABLES IN SCHEMA ' || schemaname || ' TO ybvoyager;' FROM informationschema.schemata; \gexec SELECT 'GRANT SELECT ON ALL SEQUENCES IN SCHEMA ' || schemaname || ' TO ybvoyager;' FROM

\gexec ``` Create a replication group as follows: ```sql CREATE ROLE replication_group; ``` Add the original owner of the table to the group as follows: ```sql GRANT replicationgroup TO <originalowner>; ``` Add the user `ybvoyager` to the replication group as follows: ```sql GRANT replication_group TO ybvoyager; ``` Transfer ownership of the tables to the role `replication_group` as follows: ```sql DO $$ DECLARE r Record; BEGIN FOR r IN (SELECT tableschema, '"' || tablename || '"' as tname FROM informationschema.tables WHERE tableschema IN (<SCHEMALIST>)) LOOP EXECUTE 'ALTER TABLE ' || r.tableschema || '.' || r.tname || ' OWNER TO replication_group'; END LOOP; END $$; SCHEMALIST used is a comma-separated list of schemas, for example, SCHEMALIST 'abc','public', 'xyz'. ``` Grant `CREATE` privilege on the source database to `ybvoyager` as follows: ```sql GRANT CREATE ON DATABASE <database_name> TO ybvoyager; --required to create a publication. ``` The `ybvoyager` user can now be used for migration. {{% /tab %}} {{< /tabpane >}} </div> If you want yb-voyager to connect to the source database over SSL, refer to . {{< note title="Connecting to Oracle instances" >}} You can use only one of the following arguments to connect to your Oracle instance. --source-db-schema (Schema name of the source database.) --oracle-db-sid (Oracle System Identifier you can use while exporting data from Oracle instances.) --oracle-tns-alias (TNS (Transparent Network Substrate) alias configured to establish a secure connection with the server.) {{< /note >}} Prepare your target YugabyteDB database cluster by creating a database, and a user for your cluster. {{<note title="Important">}} Add the following flags to the cluster before starting migration, and revert them after the migration is complete. For the target YugabyteDB versions `2.18.5.1` and `2.18.6.0` (or later minor versions), set the following flag: ```sh ysqlpgconfcsv = ybmaxquerylayer_retries=0 ``` For all the other target YugabyteDB versions, set the following flags: ```sh ysqlmaxreadrestartattempts = 0 ysqlmaxwriterestartattempts = 0 ``` Turn off the isolation level on the target YugabyteDB cluster during the migration. {{</note>}} Create the target YugabyteDB database in your YugabyteDB cluster. The database name can be the same or different from the source database name. If you don't provide the target YugabyteDB database name during import, yb-voyager assumes the target YugabyteDB database name is `yugabyte`. To specify the target YugabyteDB database name during import, use the `--target-db-name` argument with the `yb-voyager import` commands. ```sql CREATE DATABASE targetdbname; ``` Create a user with role. For a local YugabyteDB cluster or YugabyteDB Anywhere, create a user and role with the superuser privileges using the following command: ```sql CREATE USER ybvoyager SUPERUSER PASSWORD 'password'; ``` For YugabyteDB Managed, create a user with role using the following command: ```sql 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 . {{< warning title="Deleting the ybvoyager user" >}} After migration, all the migrated objects (tables, views, and so on) are owned by the `ybvoyager` user. You should transfer the ownership of the objects to some other user (for example, `yugabyte`) and then delete the `ybvoyager` user. Example steps to delete the user are: ```sql REASSIGN OWNED BY ybvoyager TO yugabyte; DROP OWNED BY ybvoyager; DROP USER ybvoyager; ``` {{< /warning >}} 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. Next, you should provide the path of the export directory as a mandatory argument (`--export-dir`) to each invocation of the yb-voyager command in an environment variable. ```sh mkdir $HOME/export-dir export EXPORT_DIR=$HOME/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

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. Proceed with schema and data migration using the following steps: To begin, export the schema from the source database. Once exported, analyze the schema and apply any necessary manual changes. 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. {{< note title="Usage for sourcedbschema" >}} The `sourcedbschema` argument specifies the schema of the source database. For Oracle, `source-db-schema` can take only one schema name and you can migrate only one schema at a time. {{< /note >}} An example invocation of the command with required arguments is as follows: ```sh yb-voyager export schema --export-dir <EXPORT_DIR> \ --source-db-type <SOURCEDBTYPE> \ --source-db-host <SOURCEDBHOST> \ --source-db-user <SOURCEDBUSER> \ --source-db-password <SOURCEDBPASSWORD> \ # Enclose the password in single quotes if it contains special characters. --source-db-name <SOURCEDBNAME> \ --source-db-schema <SOURCEDBSCHEMA> ``` Refer to for details about the arguments. 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 step, and prepares a report that lists the DDL statements which need manual changes. An example invocation of the command with required arguments is as follows: ```sh yb-voyager analyze-schema --export-dir <EXPORT_DIR> --output-format <FORMAT> ``` The preceding command generates a report file under the `EXPORT_DIR/reports/` directory. Refer to for details about the arguments. 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 . {{< note title="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. {{< /note >}} Refer to the for a detailed list of limitations and suggested workarounds associated with the source databases when migrating to YugabyteDB Voyager. Import the schema using the `yb-voyager import schema` command. {{< note title="Usage for targetdbschema" >}} `yb-voyager` imports the source database into the `public` schema of the target YugabyteDB database. By specifying `--target-db-schema` argument during import, you can instruct `yb-voyager` to create a non-public schema and use it for the schema/data import. {{< /note >}} An example invocation of the command with required arguments is as follows: ```sh yb-voyager import schema --export-dir <EXPORT_DIR> \ --target-db-host <TARGETDBHOST> \ --target-db-user <TARGETDBUSER> \ --target-db-password <TARGETDBPASSWORD> \ # Enclose the password in single quotes if it contains special characters.. --target-db-name <TARGETDBNAME> \ --target-db-schema <TARGETDBSCHEMA> ``` Refer to for details about the arguments. yb-voyager applies the DDL SQL files located in the `$EXPORT_DIR/schema` 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`

{{< note title="Importing indexes and triggers" >}} Because the presence of indexes and triggers can slow down the rate at which data is imported, by default `import schema` does not import indexes (except UNIQUE indexes to avoid any issues during import of schema because of foreign key dependencies on the index) and triggers. You should complete the data import without creating indexes and triggers. Only after data import is complete, create indexes and triggers using the `import schema` command with an additional `--post-snapshot-import` flag. {{< /note >}} Begin exporting data from the source database into the `EXPORT_DIR/data` directory using the yb-voyager export data from source command as follows: ```sh yb-voyager export data from source --export-dir <EXPORT_DIR> \ --source-db-type <SOURCEDBTYPE> \ --source-db-host <SOURCEDBHOST> \ --source-db-user <SOURCEDBUSER> \ --source-db-password <SOURCEDBPASSWORD> \ # Enclose the password in single quotes if it contains special characters. --source-db-name <SOURCEDBNAME> \ --source-db-schema <SOURCEDBSCHEMA> \ --export-type snapshot-and-changes ``` The export data command first ensures that it exports a snapshot of the data already present on the source database. Next, you start a streaming phase (CDC phase) where you begin capturing new changes made to the data on the source after the migration has started. Some important metrics such as the number of events, export rate, and so on, is displayed during the CDC phase similar to the following: ```output | | -- | | Metric | Value | | | -- | | Total Exported Events | 123456 | | Total Exported Events (Current Run) | 123456 | | Export Rate(Last 3 min) | 22133/sec | | Export Rate(Last 10 min) | 21011/sec | | | -- | ``` Note that the CDC phase will start only after a snapshot of the entire table-set is completed. Additionally, the CDC phase is restartable. So, if yb-voyager terminates when data export is in progress, it resumes from its current state after the CDC phase is restarted. {{<note title="Important">}} yb-voyager creates a replication slot in the source database where disk space can be used up rapidly. To avoid this, execute the or steps to delete the replication slot. If you choose to skip these steps, then you must delete the replication slot manually to reduce disk usage. {{</note>}} Some data types are unsupported. For a detailed list, refer to . For Oracle where sequences are not attached to a column, resume value generation is unsupported. `--parallel-jobs` argument (specifies the number of tables to be exported in parallel from the source database at a time) has no effect on live migration. Refer to for details about the arguments of an export operation. The options passed to the command are similar to the command. To export only a subset of the tables, pass a comma-separated list of table names in the `--table-list` argument. Run the `yb-voyager get data-migration-report --export-dir <EXPORT_DIR>` command to get a consolidated report of the overall progress of data migration concerning all the databases involved (source and target). Refer to for details about the arguments. After you have successfully imported the schema in the target YugabyteDB database, you can start importing the data using the yb-voyager import data to target command as follows: ```sh yb-voyager import data to target --export-dir <EXPORT_DIR> \ --target-db-host <TARGETDBHOST> \ --target-db-user <TARGETDBUSER> \ --target-db-password <TARGETDBPASSWORD> \ # Enclose the password in single quotes if it contains special characters. --target-db-name <TARGETDBNAME> \ --target-db-schema <TARGETDBSCHEMA> \ # Oracle only. --parallel-jobs <NUMBEROFJOBS> ``` Refer to for details about the arguments. For the snapshot exported, 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

After the snapshot is imported, a similar approach is employed for the CDC phase, where concurrent batches of change events are applied on the target YugabyteDB database cluster. Some important metrics such as the number of events, ingestion rate, and so on, is displayed during the CDC phase similar to the following: ```output | -- | -- | | Metric | Value | | -- | -- | | Total Imported events | 272572 | | Events Imported in this Run | 272572 | | Ingestion Rate (last 3 mins) | 14542 events/sec | | Ingestion Rate (last 10 mins) | 14542 events/sec | | Time taken in this Run | 0.83 mins | | Remaining Events | 4727427 | | Estimated Time to catch up | 5m42s | | -- | -- | ``` The entire import process is designed to be restartable if yb-voyager terminates when the data import is in progress. If restarted, the data import resumes from its current state. {{< note title="Note">}} The arguments `table-list` and `exclude-table-list` are not supported in live migration. For details about the arguments, refer to the . {{< /note >}} {{< tip title="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 to target` 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. {{< /tip >}} Run the following command with required arguments to get a consolidated report of the overall progress of data migration concerning all the databases involved (source or target). ```sh yb-voyager get data-migration-report --export-dir <EXPORT_DIR> \ --target-db-password <TARGETDBPASSWORD> ``` Refer to for details about the arguments. Import indexes and triggers on the target YugabyteDB database after the `import data to target` has completed the following tasks: The exported snapshot has been completely imported on the target. All the events accumulated on local disk by during the snapshot import phase and have caught up in the CDC phase (you can monitor the timeline based on `Estimated Time to catch up` metric). After the preceding steps are completed, you can start importing indexes and triggers in parallel with the `import data to target` command using the `import schema` command with an additional `--post-snapshot-import` flag as follows: ```sh yb-voyager import schema --export-dir <EXPORT_DIR> \ --target-db-host <TARGETDBHOST> \ --target-db-user <TARGETDBUSER> \ --target-db-password <TARGETDBPASSWORD> \ # Enclose the password in single quotes if it contains special characters. --target-db-name <TARGETDBNAME> \ --target-db-schema <TARGETDBSCHEMA> \ --post-snapshot-import true ``` If any of the CREATE INDEX DDLs fail in the preceding command, retry the command with the argument `--ignore-exist` to ignore already created indexes and create new ones instead. ```sh yb-voyager import schema --export-dir <EXPORT_DIR> \ --target-db-host <TARGETDBHOST> \ --target-db-user <TARGETDBUSER> \ --target-db-password <TARGETDBPASSWORD> \ # Enclose the password in single quotes if it contains special characters. --target-db-name <TARGETDBNAME> \ --target-db-schema <TARGETDBSCHEMA> \ --post-snapshot-import true \ --ignore-exist true ``` Refer to for details about the arguments. As the migration continuously exports changes on the source database to the `EXPORT-DIR`, disk use continues to grow. To prevent the disk from filling up, you can optionally use the `archive changes` command as follows: ```sh yb-voyager archive changes --export-dir <EXPORT-DIR> --move-to <DESTINATION-DIR> ``` Refer to for details about the arguments. Cutover is the last phase, where you switch your application over from the source database to the target YugabyteDB

Keep monitoring the metrics displayed for export data and import data processes. After you notice that the import of events is catching up to the exported events, you are ready to perform a cutover. You can use the "Remaining events" metric displayed in the import data process to help you determine the cutover. Perform the following steps as part of the cutover process: Quiesce your source database, that is stop application writes. Perform a cutover after the exported events rate ("Export rate" in the metrics table) drops to 0 using the following command: ```sh yb-voyager initiate cutover to target --export-dir <EXPORT_DIR> --prepare-for-fall-back false ``` Refer to for details about the arguments. The initiate cutover to target command stops the export data process, followed by the import data process after it has imported all the events to the target YugabyteDB database. Wait for the cutover process to complete. Monitor the status of the cutover process using the following command: ```sh yb-voyager cutover status --export-dir <EXPORT_DIR> ``` Refer to for details about the arguments. If there are in the migration, refresh them manually after cutover. After the schema and data import is complete, the automated part of the database migration process is considered complete. You should manually run validation queries on both the source and target YugabyteDB database to ensure that the data is correctly migrated. A sample query to validate the databases can include checking the row count of each table. {{< warning title = "Caveat associated with rows reported by get data-migration-report" >}} Suppose you have a scenario where, or 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, command reports an incorrect number of imported rows, because it doesn't take into account the deleted rows. For more details, refer to GitHub issue . {{< /warning >}} 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. Run the `yb-voyager end migration` command to perform the clean up, and to back up the schema, data, migration reports, and log files by providing the backup related flags (mandatory) as follows: ```sh 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> \ --backup-dir <BACKUP_DIR> ``` Note that after you end the migration, you will not be able to continue further. If you wish to back up the schema, data, log files, and the migration reports (`analyze-schema` report and `get data-migration-report` output) for future reference, the command provides an additional argument `--backup-dir`, using which you can pass the path of the directory where the backup content needs to be saved (based on what you choose to back up). Refer to for more details on the arguments. Schema changes on the source Oracle database will not be recognized during the live migration. Tables without primary key are not supported. Truncating a table on the source database is not taken into account; you need to manually truncate tables on your YugabyteDB cluster. Some Oracle data types are unsupported - User Defined Types (UDT), NCHAR, NVARCHAR, VARRAY, BLOB, CLOB, and NCLOB. Case-sensitive table names or column names are partially supported. YugabyteDB Voyager converts them to case-insensitive names. For example, an "Accounts" table in a source Oracle database is migrated as `accounts` (case-insensitive) to a YugabyteDB database. Tables or column names having more than 30 characters