This section contains some ideas for troubleshooting common problems experienced with data retention.
"<TYPE_OF_BACKGROUND_JOB>": failed to start a background worker
You might see this error message in the logs if background workers aren't properly configured.
To fix this error, make sure that
timescaledb.max_background_workers are properly
timescaledb.max_background_workers should equal the number of databases
plus the number of concurrent background workers.
equal the sum of
For more information, see the worker configuration docs.
A retention policy set on a hypertable does not apply to any continuous aggregates made from the hypertable. This allows you to set different retention periods for raw and summarized data. To apply a retention policy to a continuous aggregate, set the policy on the continuous aggregate itself.
When you drop a chunk, it requires an exclusive lock. If a chunk is being accessed by another session, you cannot drop the chunk at the same time. If a drop chunk operation can't get the lock on the chunk, then it times out and the process fails. To resolve this problem, check what is locking the chunk. In some cases, this could be caused by a continuous aggregate or other process accessing the chunk. When the drop chunk operation can get an exclusive lock on the chunk, it completes as expected.
For more information about locks, see the PostgreSQL lock monitoring documentation.
ERROR: invalid attribute number -6 for _hyper_2_839_chunkCONTEXT: SQL function "hypertable_local_size" statement 1 PL/pgSQL function hypertable_detailed_size(regclass) line 26 at RETURN QUERY SQL function "hypertable_size" statement 1SQL state: XX000
You might see this error if your hypertable indexes have become very large. To resolve the problem, reindex your hypertables with this command:
reindex table _timescaledb_internal._hyper_2_1523284_chunk
For more information, see the hypertable documentation.
Your scheduled jobs might stop running for various reasons. On self-hosted TimescaleDB, you can fix this by restarting background workers:
On Timescale Cloud and Managed Service for TimescaleDB, restart background workers by doing one of the following:
SELECT timescaledb_pre_restore(), followed by
- Power the service off and on again. This might cause a downtime of a few minutes while the service restores from backup and replays the write-ahead log.
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