Reorder Policies

A reorder policy reorganizes data in a hypertable's chunks to match the order of a specific index. This process can significantly improve query performance, especially for queries that read data in the index's order, as it reduces the number of disk pages that need to be read. The policy intelligently reorders all chunks except for the two most recent ones, which are typically still receiving active writes. By default, this optimization job runs once every 24 hours, but the schedule is fully configurable.

You can have only one reorder policy on each hypertable.

See also: add_reorder_policy

Example

Here is a complete example of configuring a reorder policy on a DeviceReading hypertable with the first string in the ReorderPolicy attribute defining the IndexName.

[Hypertable(nameof(Time))]
[ReorderPolicy("DeviceReadings_Time_idx", InitialStart = "2025-09-23T09:15:19.3905112Z", ScheduleInterval = "1 day", MaxRuntime = "00:00:00", RetryPeriod = "00:05:00", MaxRetries = 3)]
[PrimaryKey(nameof(Id), nameof(Time))]
public class DeviceReading
{
    public Guid Id { get; set; }
    public DateTime Time { get; set; }
    public string DeviceId { get; set; } = string.Empty;
    public double Voltage { get; set; }
    public double Power { get; set; }
}

Supported parameters

Parameter	Description	Type	Database Type	DefaultValue
IndexName *	The name of the existing index that the reorder policy should use to sort the data.	string	regclass	string.Empty
InitialStart	The first time the policy job is scheduled to run, specified as a UTC date-time string in ISO 8601 format. If null, the first run is based on the schedule_interval.	string?	TIMESTAMPTZ	null
ScheduleInterval	The interval at which the reorder policy job runs. If null, it defaults to '1 day'.	string?	INTERVAL	'1 day'
MaxRuntime	The maximum amount of time the job is allowed to run before being stopped. If null, there is no time limit.	string?	INTERVAL	null
MaxRetries	The number of times the job is retried if it fails.	int	INTEGER	-1
RetryPeriod	The amount of time the scheduler waits between retries of a failed job. If null, it defaults to '00:05:00' (5 minutes).	string?	INTERVAL	'00:05:00'

* required