Troubleshooting

ERROR: permission denied for schema _timescaledb_internal

You might see this error when using the ALTER TABLE command to change the ownership of tables or hypertables.

This use of ALTER TABLE is blocked because the tsdbadmin user is not a superuser.

To change table ownership, use the REASSIGN command instead:

REASSIGN OWNED BY <current_role> TO <desired_role>

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ERROR:  could not create unique index
DETAIL:  Table contains duplicated values.

When you try to rebuild index with REINDEX it fails because of conflicting duplicated rows.

To identify conflicting duplicate rows, you need to run a query that counts the number of rows for each combination of columns included in the index definition.

For example, this route table has a unique_route_index index defining unique rows based on the combination of the source and destination columns:

CREATE TABLE route(
    source TEXT,
    destination TEXT,
    description TEXT
    );

CREATE UNIQUE INDEX unique_route_index
    ON route (source, destination);

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If the unique_route_index is corrupt, you can find duplicated rows in the route table using this query:

SELECT
    source,
    destination,
    count
FROM
    (SELECT
        source,
        destination,
        COUNT(*) AS count
    FROM route
    GROUP BY
        source,
        destination) AS foo
WHERE count > 1;

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The query groups the data by the same source and destination fields defined in the index, and filters any entries with more than one occurrence.

Resolve the problematic entries in the rows by manually deleting or merging the entries until no duplicates exist. After all duplicate entries are removed, you can use the REINDEX command to rebuild the index.

Your Managed Service for TimescaleDB service, in project "ExampleAccount", is running low on
CPU. Running low on CPU affects performance and could affect service
availability. Please either optimize your usage pattern or reduce the workload,
and consider upgrading to a larger plan to avoid service outage.

When your database reaches 90% of your allocated disk, memory, or CPU resources, an automated message with the text above is sent to your email address.

You can resolve this by logging in to your Managed Service for TimescaleDB account and increasing your available resources. From the Managed Service for TimescaleDB Dashboard, select the service that you want to increase resources for. In the Overview tab, locate the Service Plan section, and click Upgrade Plan. Select the plan that suits your requirements, and click Upgrade to enable the additional resources.

If you run out of resources regularly, you might need to consider using your resources more efficiently. Consider enabling compression, using continuous aggregates, or configuring data retention to reduce the amount of resources your database uses.

Managed Service for TimescaleDB services require a DNS record. When you launch a new service the DNS record is created, and it can take some time for the new name to propagate to DNS servers around the world.

If you move an existing service to a new Cloud provider or region, the service is rebuilt in the new region in the background. When the service has been rebuilt in the new region, the DNS records are updated. This could cause a short interruption to your service while the DNS changes are propagated.

If you are unable to resolve DNS, wait a few minutes and try again.

The transaction control mechanism in PostgreSQL assigns a transaction ID to every row that is modified in the database; these IDs control the visibility of that row to other concurrent transactions. The transaction ID is a 32-bit number where two billion IDs are always in the visible past and the remaining IDs are reserved for future transactions and are not visible to the running transaction. To avoid a transaction wraparound of old rows, PostgreSQL requires occasional cleanup and freezing of old rows. This ensures that existing rows are visible when more transactions are created. You can manually freeze the old rows by executing VACUUM FREEZE. It can also be done automatically using the autovacuum daemon when a configured number of transactions has been created since the last freeze point.

In Managed Service for TimescaleDB, the transaction limit is set according to the size of the database, up to 1.5 billion transactions. This ensures 500 million transaction IDs are available before a forced freeze and avoids churning stable data in existing tables. To check your transaction freeze limits, you can execute show autovacuum_freeze_max_age in your PostgreSQL instance. When the limit is reached, autovacuum starts freezing the old rows. Some applications do not automatically adjust the configuration when the PostgreSQL settings change, which can result in unnecessary warnings. For example, PGHero's default settings alert when 500 million transactions have been created instead of alerting after 1.5 billion transactions. To avoid this, change the value of the transaction_id_danger setting from 1,500,000,000 to 500,000,000, to receive warnings when the transaction limit reaches 1.5 billion.