set_chunk_time_interval.md

api_name	set_chunk_time_interval()
excerpt	Change the chunk time interval of a hypertable
topics	hypertables
keywords	chunks hypertables
tags	time ranges time intervals
api	license type apache function
products	cloud mst self_hosted

set_chunk_time_interval()

Sets the chunk_time_interval on a hypertable. The new interval is used when new chunks are created, and time intervals on existing chunks are not changed.

Samples

For a TIMESTAMP column, set chunk_time_interval to 24 hours:

SELECT set_chunk_time_interval('conditions', INTERVAL '24 hours');
SELECT set_chunk_time_interval('conditions', 86400000000);

For a time column expressed as the number of milliseconds since the UNIX epoch, set chunk_time_interval to 24 hours:

SELECT set_chunk_time_interval('conditions', 86400000);

Arguments

Name	Type	Default	Required	Description
hypertable	REGCLASS	-	✔	Hypertable or continuous aggregate to update interval for.
chunk_time_interval	See note	-	✔	Event time that each new chunk covers.
dimension_name	REGCLASS	-	✖	The name of the time dimension to set the number of partitions for. Only use dimension_name when your hypertable has multiple time dimensions.

If you change chunk time interval you may see a chunk that is smaller than the new interval. For example, if you have two 7-day chunks that cover 14 days, then change chunk_time_interval to 3 days, you may end up with a transition chunk covering one day. This happens because the start and end of the new chunk is calculated based on dividing the timeline by the chunk_time_interval starting at epoch 0. This leads to the following chunks [0, 3), [3, 6), [6, 9), [9, 12), [12, 15), [15, 18) and so on. The two 7-day chunks covered data up to day 14: [0, 7), [8, 14), so the 3-day chunk for [12, 15) is reduced to a one day chunk. The following chunk [15, 18) is created as a full 3 day chunk.

The valid types for the chunk_time_interval depend on the type used for the hypertable time column:

time column type	chunk_time_interval type	Time unit
TIMESTAMP	INTERVAL	days, hours, minutes, etc
	INTEGER or BIGINT	microseconds
TIMESTAMPTZ	INTERVAL	days, hours, minutes, etc
	INTEGER or BIGINT	microseconds
DATE	INTERVAL	days, hours, minutes, etc
	INTEGER or BIGINT	microseconds
SMALLINT	SMALLINT	The same time unit as the time column
INT	INT	The same time unit as the time column
BIGINT	BIGINT	The same time unit as the time column

For more information, see hypertable partitioning.