create_hypertable()

Since 0.1.0

Replace a standard PostgreSQL relational table with a hypertable that is partitioned on a single dimension. To create a new hypertable, best practice is to call CREATE TABLE.

A hypertable is a PostgreSQL table that automatically partitions your data by time. A dimension defines the way your data is partitioned. All actions work on the resulting hypertable. For example, ALTER TABLE, and SELECT.

If the table to convert already contains data, set migrate_data to TRUE. However, this may take a long time and there are limitations when the table contains foreign key constraints.

You cannot run create_hypertable() on a table that is already partitioned using declarative partitioning or inheritance. The time column must be defined as NOT NULL. If this is not already specified on table creation, create_hypertable automatically adds this constraint on the table when it is executed.

This page describes the generalized hypertable API introduced in TimescaleDB v2.13. The old interface for create_hypertable is also available.

Samples

Before you call create_hypertable, you create a standard PostgreSQL relational table. For example:

CREATE TABLE conditions (
   time        TIMESTAMPTZ         NOT NULL,
   location    text                NOT NULL,
   temperature DOUBLE PRECISION    NULL
);

The following examples show you how to create a hypertable from an existing table or a function:

• Time partition a hypertable by time range
• Time partition a hypertable using composite columns and immutable functions
• Time partition a hypertable using ISO formatting
• Time partition a hypertable using UUIDv7

Time partition a hypertable by time range

The following examples show different ways to create a hypertable:

• Convert with range partitioning on the time column:

  SELECT create_hypertable('conditions', by_range('time'));

• Convert with a set_chunk_time_interval of 24 hours: Either:

  SELECT create_hypertable('conditions', by_range('time', 86400000000));

  or:

  SELECT create_hypertable('conditions', by_range('time', INTERVAL '1 day'));

• With range partitioning on the time column, do not raise a warning if conditions is already a hypertable:

  SELECT create_hypertable('conditions', by_range('time'), if_not_exists => TRUE);

If you call SELECT * FROM create_hypertable(...) the return value is formatted as a table with column headings.

Time partition a hypertable using composite columns and immutable functions

The following example shows how to time partition the measurements relational table on a composite column type using a range partitioning function.

1. Create the report type, then an immutable function that converts the column value into a supported column value:

   CREATE TYPE report AS (reported timestamp with time zone, contents jsonb);
   
   CREATE FUNCTION report_reported(report)
     RETURNS timestamptz
     LANGUAGE SQL
     IMMUTABLE AS
     'SELECT $1.reported';

2. Create the hypertable using the immutable function:

   SELECT create_hypertable('measurements', by_range('report', partition_func => 'report_reported'));

Time partition a hypertable using ISO formatting

The following example shows how to time partition the events table on a jsonb (event) column type, which has a top level started key that contains an ISO 8601 formatted timestamp:

CREATE FUNCTION event_started(jsonb)
    RETURNS timestamptz
    LANGUAGE SQL
    IMMUTABLE AS
  $func$SELECT ($1->>'started')::timestamptz$func$;

SELECT create_hypertable('events', by_range('event', partition_func => 'event_started'));

Time partition a hypertable using UUIDv7

1. Create a table with a UUIDv7 column:

   PostgreSQL 17 and lower

   CREATE TABLE events (
       id  uuid PRIMARY KEY DEFAULT generate_uuidv7(),
       payload jsonb
   );

   PostgreSQL 18

   CREATE TABLE events (
       id  uuid PRIMARY KEY DEFAULT uuidv7(),
       payload jsonb
   );

2. Partition the table based on the timestamps embedded within the UUID values:

   SELECT create_hypertable(
       'events',
       by_range('id', INTERVAL '1 month')
   );

Subsequent data insertion and queries automatically leverage the UUIDv7-based partitioning.

Arguments

The syntax for create_hypertable is:

SELECT create_hypertable(
    relation = '<table_name>',
    dimension = by_range('<column_name>') | by_hash('<column_name>', <number_partitions>),
    create_default_indexes = true | false,
    if_not_exists = true | false,
    migrate_data = true | false
);

Name	Type	Default	Required	Description
create_default_indexes	BOOLEAN	TRUE	✖	Create default indexes on time/partitioning columns.
dimension	DIMENSION_INFO	-	✔	To create a _timescaledb_internal.dimension_info instance to partition a hypertable, you call by_range and by_hash. Note: best practice is to not use additional dimensions, especially on Tiger Cloud.
if_not_exists	BOOLEAN	FALSE	✖	Set to TRUE to print a warning if relation is already a hypertable. By default, an exception is raised.
migrate_data	BOOLEAN	FALSE	✖	Set to TRUE to migrate any existing data in relation in to chunks in the new hypertable. Depending on the amount of data to be migrated, setting migrate_data can lock the table for a significant amount of time. If there are foreign key constraints to other tables in the data to be migrated, create_hypertable() can run into deadlock. A hypertable can only contain foreign keys to another hypertable. UNIQUE and PRIMARY constraints must include the partitioning key. Deadlock may happen when concurrent transactions simultaneously try to insert data into tables that are referenced in the foreign key constraints, and into the converting table itself. To avoid deadlock, manually obtain a SHARE ROW EXCLUSIVE lock on the referenced tables before you call create_hypertable in the same transaction. If you leave migrate_data set to the default, non-empty tables generate an error when you call create_hypertable.
relation	REGCLASS	-	✔	Identifier of the table to convert to a hypertable.

Returns

Column	Type	Description
hypertable_id	INTEGER	The ID of the hypertable you created.
created	BOOLEAN	TRUE when the hypertable is created. FALSE when if_not_exists is true and no hypertable was created.

On failure, an error is returned:

Error	Description
table "<name>" is already a hypertable	The table is already a hypertable. Use if_not_exists => TRUE to suppress this error.
column "<name>" does not exist	The specified partitioning column does not exist in the table.
column "<name>" is already a dimension	The column is already used as a partitioning dimension.
cannot create a unique index without the column "<name>" (used in partitioning)	Unique and primary key constraints must include all partitioning columns.
cannot have FOREIGN KEY constraints to hypertable "<name>"	Foreign key constraints to hypertables are not supported.
cannot create hypertable for table "<name>" because it is part of a publication	Tables in publications cannot be converted to hypertables.
invalid number of partitions: must be between 1 and 32767	The number of hash partitions specified is out of valid range.
cannot specify both the number of partitions and an interval	When using by_hash, specify either the number of partitions or an interval, not both.
invalid interval type for <type> dimension	The chunk interval type does not match the partitioning column type.
must be owner of hypertable "<name>"	Only the table owner can convert it to a hypertable.