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Checkpoint Settings

For materialized views, checkpoint settings control how and where checkpoints are created, as well as whether they are incremental or asynchronous. This can be specified in the checkpoint_settings section of the materialized view settings.

CREATE MATERIALIZED VIEW mv AS
SELECT key, count() FROM test group by key
SETTINGS default_hash_table='hybrid', default_hash_join='hybrid',
checkpoint_settings = 'incremental=true;interval=5';

checkpoint_settings​

You can set key-value pairs in checkpoint_settings.

type​

Definition: Defines which checkpoint type to use.

Possible Values:

  • auto (default) - Automatically determine whether to use file or rocks checkpoint based on the query’s state type.
  • file - Native file format. You can explicitly use the local file system for the checkpoint storage, even for some materialized views, using rocksdb is recommended.

storage_type​

Definition: Specifies where checkpoints will be stored.

Possible Values:

  • auto (default) - Automatically determine whether to store in local_file_system or nativelog
  • local_file_system - Stored in local file system for a single instance environment
  • nativelog - Stored in nativelog, and ensure cluster synchronization through raft (Only valid in clusters)
  • s3 - Stored in S3, it must be bound to disk_name

async​

Definition: Determines whether checkpoints are created asynchronously.

Possible Values:

  • true (default) - Asynchronous checkpoint replication
  • false

incremental​

Definition: Indicates whether checkpoints are incremental (saving only changes since the last checkpoint) or full.

Possible Values:

  • false (default)
  • true - Only enabled when using a hybrid hash table (Recommended for large states with low update frequency)

interval​

Definition: Specifies the time interval in seconds between checkpoint operations.

Possible Values:

  • Any integer (default 0 means use a configured value)

This is also configurable via the global configuration file.

# <config.yaml>
query_state_checkpoint:
    # State checkpoint interval in seconds
    interval: 900
    ...

disk_name​

Definition: Specifies a disk name, which can be created through sqlcreate disk {disk_name} ..., which is used with a shared checkpoint storage (i.e. S3)

checkpoint_interval​

In some cases, you may want to adjust the checkpoint interval after the materialized view is created. You can do this by modifying the checkpoint_settings parameter in the ALTER VIEW statement.

ALTER VIEW mv MODIFY QUERY SETTING checkpoint_settings = 'incremental=true;interval=5';

If you don't want to repeat the other key-value pairs in the checkpoint_settings, you can use the top-level checkpoint_interval parameter, e.g.

ALTER VIEW mv MODIFY QUERY SETTING checkpoint_interval = 5;

Set checkpoint_interval to a negative integer value to disable checkpointing. Set it to 0 to use the global checkpoint interval. Set it to a positive integer value to specify the checkpoint interval in seconds.

Examples​

For some scenarios with large states and low update frequency:

CREATE MATERIALIZED VIEW mv AS
SELECT key, count() FROM test group by key
SETTINGS
default_hash_table='hybrid', default_hash_join='hybrid',
checkpoint_settings = 'incremental=true;interval=5';

For some scenarios with S3 checkpoint storage:

--- create a S3 plain disk `diskS3`
CREAET DISK diskS3 disk(
    type='s3_plain',
    endpoint='http://localhost:11111/test/s3/',
    access_key_id='timeplusd',
    secret_access_key='xxxxxxxxxx'
);

CREATE MATERIALIZED VIEW mv AS
SELECT key, count() FROM test group by key
SETTINGS
default_hash_table='hybrid', default_hash_join='hybrid',
checkpoint_settings = 'storage_type=S3;disk_name=diskS3;incremental=true;interval=5';
Last updated on by Jove Zhong