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ALTER STREAM

Currently we don't recommend to alter the schema of streams in Timeplus. You can modify the retention policy for historical store via MODIFY TTL and modify the retention policy for streaming storage via MODIFY SETTING.

You can also use ALTER VIEW to modify the settings of materialized views (only available in Timeplus Enterprise).

MODIFY TTL​

You can add or modify the retention policy. e.g.

ALTER STREAM stream_name MODIFY TTL
to_datetime(created_at) + INTERVAL 48 HOUR

MODIFY SETTING​

You can add or modify the retention policy for streaming storage. e.g.

ALTER STREAM stream_name MODIFY SETTING
logstore_retention_ms = ...,
logstore_retention_bytes = ...;

MODIFY QUERY SETTING​

info

This feature is available in Timeplus Enterprise v2.2.8 or above. Not available in Timeplus Proton.

Please use ALTER VIEW for this use cases. Altering views or materialized views will be deprecated and removed from the ALTER STREAM SQL command.

By default, the checkpoint will be updated every 15 minutes for materialized views. You can change the checkpoint interval without recreating the materialized views.

ALTER STREAM mv_with_inner_stream MODIFY QUERY SETTING checkpoint_interval=600

RESET QUERY SETTING​

info

This feature is available in Timeplus Enterprise v2.2.8 or above. Not available in Timeplus Proton.

Please use ALTER VIEW for this use cases. Altering views or materialized views will be deprecated and removed from the ALTER STREAM SQL command.

By default, the checkpoint will be updated every 15 minutes for materialized views. After you change the interval you can reset it.

ALTER STREAM mv_with_inner_stream RESET QUERY SETTING checkpoint_interval

ADD COLUMN​

info

This feature is available in single-node of Timeplus Enterprise v2.4.15 or above. Not available in cluster or Timeplus Proton.

You can add a column to an existing stream. The value of the new column in the existing rows will be set to the default value of the data type, such as 0 for integer.

Syntax:

ALTER STREAM stream_name ADD COLUMN column_name data_type

DELETE COLUMN or RENAME COLUMN are not supported yet. Contact us if you have strong use cases.

DROP PARTITION​

You can delete some data in the stream without dropping the entire stream via ALTER STREAM .. DROP PARTITION ...

By default the streams in Timeplus are partitioned by _tp_time: PARTITION BY to_YYYYMMDD(_tp_time).

You can query the system.parts table to check the partitions for the given streams:

SELECT partition, table,name,active FROM system.parts

This may show results like this:

┌─partition─┬─table─────────┬─name───────────┬─active─┐
│ 20241014  │ test_stream   │ 20241014_1_1_0 │      0 │
│ 20241014  │ test_stream   │ 20241014_1_4_1 │      1 │
│ 20241014  │ test_stream   │ 20241014_2_2_0 │      0 │
│ 20241014  │ test_stream   │ 20241014_3_3_0 │      0 │
│ 20241014  │ test_stream   │ 20241014_4_4_0 │      0 │
│ 20241015  │ test_stream   │ 20241015_5_5_0 │      1 │
└───────────┴───────────────┴────────────────┴────────┘

You can delete data in certain partitions via SQL:

ALTER STREAM stream DROP PARTITION partition

Such as

ALTER STREAM test_stream DROP PARTITION 20241015

See also​

Last updated on by Jove Zhong