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Aiven for ClickHouse® limits and limitations

By respecting Aiven for ClickHouse® restrictions and quotas, you can improve the security and productivity of your service workloads.

Limitations​

From the information about restrictions on using Aiven for ClickHouse, you can draw conclusions on how to get your service to operate closer to its full potential. Use Recommended approach as guidelines on how to work around specific restrictions.

NameDescriptionRecommended approach
Backups - one snapshot a day

Since Aiven for ClickHouse service takes a single snapshot a day only:

  • When powering off the service, all data after the last backup is lost.
  • Point-in-time recovery is not supported. A database can be restored to one of the daily backups states only.
  • When creating a database fork, you can only create a fork that matches the state of one of the backups.
  • Any data inserted before the next snapshot is lost if all nodes in a given shard malfunction and need to be replaced. This limitation doesn't apply to patches, migrations, or scaling, which are handled safely and automatically.
Service integrations

You can integrate your Aiven for ClickHouse service with PostgreSQL® and Kafka® only.

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Table engines support

  • Some special table engines are not supported in Aiven for ClickHouse.

  • Some engines are remapped to their Replicated alternatives, for example, MergeTree > ReplicatedMergeTree.

Use the available table engines listed in Supported table engines in Aiven for ClickHouse.

Log table engine support

Log engine is not supported in Aiven for ClickHouse.

For storing data, use the Buffer engine instead of the Log engine.

Kafka table engine support

The Kafka table engine is supported via integration only, not by creating a table in SQL.

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Kafka Schema Registry

Kafka Schema Registry is supported with Aiven for Apache Kafka® and not with an external Kafka endpoint.

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Cloud availability

Available on AWS, GCP, and Azure only

Use the available cloud providers.

Querying all shards at once

If you have a sharded plan, you must use a distributed table on top of your MergeTree table to query all the shards at the same time, and you should use it for inserts too.

Use a distributed table with sharded plans. Check Query data across shards for the instructions.

ON CLUSTER queries

Aiven for ClickHouse doesn't support ON CLUSTER queries because it actually runs each data definition query on all the servers of the cluster without using ON CLUSTER.

Run queries without ON CLUSTER.

Creating a database using SQL

You cannot create a database directly using SQL, for example, if you'd like to add a non-default database.

Use the Aiven's public API.

Scaling down the number of nodes

You only can scale up the number of nodes in a cluster.

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Limits​

Service limits are determined by a plan that this service uses.

Aiven for ClickHouseHobbyistStartupBusinessPremium
VMs1136 - 30
CPU per VM1 (2 for AWS only)22 - 82 - 8
RAM per VM4 GB16 GB16 - 64 GB16 - 64 GB
Total storage180 GB1150 GB1150 - 4600 GB2300 - 46000 GB
Maximum concurrent queries25 queries per 4 GB of RAM100 queries per 16 GB of RAM100 queries per 16 GB of RAM100 queries per 16 GB of RAM
Maximum concurrent connections1000 connections per node4000 connections per node4000 connections per node4000 connections per node
tip

If you need a custom plan with capacity beyond the listed limits, contact us.