--- title: Troubleshoot import and ingest | Tiger Data Docs description: Solutions to common errors when importing data and migrating databases --- Imports and migrations often fail on version skew, encoding edge cases, or bulk-load limits. Start with these answers before you spend time debugging alone. Live import from a database Unsupported in live migration Live migration tooling is currently experimental. You may run into the following shortcomings: - Live migration does not yet support mutable columnstore compression (`INSERT`, `UPDATE`, `DELETE` on data in the columnstore). - By default, numeric fields containing `NaN`/`+Inf`/`-Inf` values are not correctly replicated, and will be converted to `NULL`. A workaround is available, but is not enabled by default. Should you run into any problems, please open a support request before losing any time debugging issues. You can open a support request directly from Tiger Console, or by email to . Where can I find logs for processes running during live migration? Live migration involves several background processes to manage different stages of the migration. The logs of these processes can be helpful for troubleshooting unexpected behavior. You can find these logs in the `/logs` directory. Source and target databases have different TimescaleDB versions When you migrate a self-hosted or Managed Service for TimescaleDB database to Tiger Cloud, the source database and the destination Tiger Cloud service must run the same version of TimescaleDB. Before you start live migration: 1. Check the version of TimescaleDB running on the source database and the target Tiger Cloud service: 2. If the version of TimescaleDB on the source database is lower than your Tiger Cloud service, either: - **Downgrade**: reinstall an older version of TimescaleDB on your Tiger Cloud service that matches the source database: 1. Connect to your Tiger Cloud service and check the versions of TimescaleDB available: 2. If an available TimescaleDB release matches your source database: 1. Uninstall TimescaleDB from your Tiger Cloud service: 2. Reinstall the correct version of TimescaleDB: You may need to reconnect to your Tiger Cloud service using `psql -X` when you’re creating the TimescaleDB extension. - **Upgrade**: for self-hosted databases, upgrade TimescaleDB to match your Tiger Cloud service. Why does live migration log “no tuple identifier” warning? Live migration logs a warning `WARNING: no tuple identifier for UPDATE in table` when it cannot determine which specific rows should be updated after receiving an `UPDATE` statement from the source database during replication. This occurs when tables in the source database that receive `UPDATE` statements lack either a `PRIMARY KEY` or a `REPLICA IDENTITY` setting. For live migration to successfully replicate `UPDATE` and `DELETE` statements, tables must have either a `PRIMARY KEY` or `REPLICA IDENTITY` set as a prerequisite. Set REPLICA IDENTITY on PostgreSQL partitioned tables If your PostgreSQL tables use native partitioning, setting `REPLICA IDENTITY` on the root (parent) table will not automatically apply it to the partitioned child tables. You must manually set `REPLICA IDENTITY` on each partitioned child table. Can I use read/failover replicas as source database for live migration? Live migration does not support replication from read or failover replicas. You must provide a connection string that points directly to your source database for live migration. Can I use live migration with a PostgreSQL connection pooler like PgBouncer? Live migration does not support connection poolers. You must provide a connection string that points directly to your source and target databases for live migration to work smoothly. Can I use Tiger Cloud instance as source for live migration? No, Tiger Cloud cannot be used as a source database for live migration. How can I exclude a schema/table from being replicated in live migration? At present, live migration does not allow for excluding schemas or tables from replication, but this feature is expected to be added in future releases. However, a workaround is available for skipping table data using the `--skip-table-data` flag. For more information, please refer to the help text under the `migrate` subcommand. Large migrations blocked Tiger Cloud automatically manages the underlying disk volume. Due to platform limitations, it is only possible to resize the disk once every six hours. Depending on the rate at which you’re able to copy data, you may be affected by this restriction. Affected instances are unable to accept new data and error with: `FATAL: terminating connection due to administrator command`. If you intend on migrating more than 400 GB of data to Tiger Cloud, open a support request requesting the required storage to be pre-allocated in your Tiger Cloud service. You can open a support request directly from Tiger Console, or by email to . Import from a database with downtime Dumping and locks When `pg_dump` starts, it takes an `ACCESS SHARE` lock on all tables which it dumps. This ensures that tables aren’t dropped before `pg_dump` is able to drop them. A side effect of this is that any query which tries to take an `ACCESS EXCLUSIVE` lock on a table is be blocked by the `ACCESS SHARE` lock. A number of Tiger Cloud-internal processes require taking `ACCESS EXCLUSIVE` locks to ensure consistency of the data. The following is a non-exhaustive list of potentially affected operations: - converting a chunk into the columnstore/rowstore and back - continuous aggregate refresh (before 2.12) - create hypertable with foreign keys, truncate hypertable - enable hypercore on a hypertable - drop chunks The most likely impact of the above is that background jobs for retention policies, columnstore compression policies, and continuous aggregate refresh policies are blocked for the duration of the `pg_dump` command. This may have unintended consequences for your database performance. Dumping with concurrency When using the `pg_dump` directory format, it is possible to use concurrency to use multiple connections to the source database to dump data. This speeds up the dump process. Due to the fact that there are multiple connections, it is possible for `pg_dump` to end up in a deadlock situation. When it detects a deadlock it aborts the dump. In principle, any query which takes an `ACCESS EXCLUSIVE` lock on a table causes such a deadlock. As mentioned above, some common operations which take an `ACCESS EXCLUSIVE` lock are: - retention policies - columnstore compression policies - continuous aggregate refresh policies If you would like to use concurrency nonetheless, turn off all background jobs in the source database before running `pg_dump`, and turn them on once the dump is complete. If the dump procedure takes longer than the continuous aggregate refresh policy’s window, you must manually refresh the continuous aggregate in the correct time range. For more information, consult the [refresh policies documentation](/docs/build/continuous-aggregates/refresh-policies/index.md). To turn off the jobs: To turn on the jobs: Restoring with concurrency If the directory format is used for `pg_dump` and `pg_restore`, concurrency can be employed to speed up the process. Unfortunately, loading the tables in the `timescaledb_catalog` schema concurrently causes errors. Furthermore, the `tsdbadmin` user does not have sufficient privileges to turn off triggers in this schema. To get around this limitation, load this schema serially, and then load the rest of the database concurrently. Ownership of background jobs The `_timescaledb_config` schema is an internal schema not part of the public API. For normal job management, use the [`timescaledb_information.jobs`](/docs/reference/timescaledb/informational-views/jobs/index.md) informational view and job management functions. Direct modification of internal tables should only be done in migration scenarios as described below. The `_timescaledb_config.bgw_jobs` table is used to manage background jobs. This includes custom jobs, columnstore compression policies, retention policies, and continuous aggregate refresh policies. On Tiger Cloud, this table has a trigger which ensures that no database user can create or modify jobs owned by another database user. This trigger can provide an obstacle for migrations. If the `--no-owner` flag is used with `pg_dump` and `pg_restore`, all objects in the target database are owned by the user that ran `pg_restore`, likely `tsdbadmin`. If all the background jobs in the source database were owned by a user of the same name as the user running the restore (again likely `tsdbadmin`), then loading the `_timescaledb_config.bgw_jobs` table should work. If the background jobs in the source were owned by the `postgres` user, they are be automatically changed to be owned by the `tsdbadmin` user. In this case, one just needs to verify that the jobs do not make use of privileges that the `tsdbadmin` user does not possess. If background jobs are owned by one or more users other than the user employed in restoring, then there could be issues. To work around this issue, do not dump this table with `pg_dump`. Provide either `--exclude-table-data='_timescaledb_config.bgw_job'` or `--exclude-table='_timescaledb_config.bgw_job'` to `pg_dump` to skip this table. Then, use `psql` and the `COPY` command to dump and restore this table with modified values for the `owner` column. Once the table has been loaded and the restore completed, you may then use SQL to adjust the ownership of the jobs and/or the associated stored procedures and functions as you wish. Common issues Extension availability There are a vast number of PostgreSQL extensions available in the wild. Tiger Cloud supports many of the most popular extensions, but not all extensions. Before migrating, check that the extensions you are using are supported on Tiger Cloud. Consult the list of supported extensions. TimescaleDB extension in the public schema When self-hosting, the TimescaleDB extension may be installed in an arbitrary schema. Tiger Cloud only supports installing the TimescaleDB extension in the `public` schema. How to go about resolving this depends heavily on the particular details of the source schema and the migration approach chosen. Tablespaces Tiger Cloud does not support using custom tablespaces. Providing the `--no-tablespaces` flag to `pg_dump` and `pg_restore` when dumping/restoring the schema results in all objects being in the default tablespace as desired. Only one database per instance While PostgreSQL clusters can contain many databases, Tiger Cloud services are limited to a single database. When migrating a cluster with multiple databases to Tiger Cloud, one can either migrate each source database to a separate Tiger Cloud service or “merge” source databases to target schemas. Superuser privileges The `tsdbadmin` database user is the most powerful available on Tiger Cloud, but it is not a true superuser. Review your application for use of superuser privileged operations and mitigate before migrating. Migrate partial continuous aggregates In order to improve the performance and compatibility of continuous aggregates, TimescaleDB v2.7 replaces *partial* continuous aggregates with *finalized* continuous aggregates. To test your database for partial continuous aggregates, run the following query: If you have partial continuous aggregates in your database, migrate them from partial to finalized before you migrate your database. If you accidentally migrate partial continuous aggregates across PostgreSQL versions, you see the following error when you query any continuous aggregates: