diff --git a/api/hypertable/set_chunk_time_interval.md b/api/hypertable/set_chunk_time_interval.md index 9231552db4..224de2a152 100644 --- a/api/hypertable/set_chunk_time_interval.md +++ b/api/hypertable/set_chunk_time_interval.md @@ -32,12 +32,22 @@ UNIX epoch, set `chunk_time_interval` to 24 hours: SELECT set_chunk_time_interval('conditions', 86400000); ``` -## Required arguments +## Arguments -|Name|Type|Description| -|-|-|-| -|`hypertable`|REGCLASS|Hypertable or continuous aggregate to update interval for| -|`chunk_time_interval`|See note|Event time that each new chunk covers| + +| 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: @@ -56,15 +66,5 @@ hypertable `time` column: For more information, see [hypertable partitioning][hypertable-partitioning]. -## Optional arguments - -|TEXT|Description| -|-|-|-| -|`dimension_name`|REGCLASS|The name of the time dimension to set the number of partitions for| - -You need to use `dimension_name` argument only if your hypertable has multiple -time dimensions. - - [hypertable-partitioning]: /use-timescale/:currentVersion:/hypertables/#hypertable-partitioning