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Partition manager extension EARLY ACCESS

PostgreSQL Partition Manager (pg_partman) is an extension to create and manage both time-based and serial-based table partition sets. pg_partman simplifies managing table partitions based on time or serial IDs, automating their creation and maintenance. While it includes many options, only a few are typically needed, making it user-friendly.

Partitioning in YugabyteDB refers to physically dividing large tables into smaller, more manageable tables to improve performance. Typically, tables with columns containing timestamps are subject to partitioning because of the historical and predictable nature of their data.

YugabyteDB fully supports pg_partman, with some minor limitations due to its distributed nature that don't hinder partition management.

For more information on partitioning in YugabyteDB, see Table partitioning
For a full list of options, see the pg_partman documentation

Enable pg_partman

Enable the pg_partman extension separately for each database.

To enable pg_partman for a specific database, create the partition maintenance schema (by default the public schema is selected), and then create the pg_partman extension. For example:

CREATE SCHEMA partman;
CREATE EXTENSION pg_partman WITH SCHEMA partman;

Use pg_partman

To demonstrate its use, create the following sample database table, orders, partitioned based on a timestamp column:

CREATE TABLE orders (
    order_id SERIAL,
    order_date DATE NOT NULL,
    customer_id INT
) PARTITION BY RANGE (order_date);

create_parent function

After you enable pg_partman, use the create_parent() function to set up table partitions. This function allows you to configure partitions in the schema designated for partition maintenance.

Use the create_parent() function as follows:

SELECT partman.create_parent(
    p_parent_table => 'public.orders',
    p_control => 'order_date',
    p_type => 'native',
    p_interval => 'monthly',
    p_premake => 5
);

  • p_parent_table - Parent partitioned table.

  • p_control - Column on which table partitioning is done. Must be an integer or time-based.

  • p_type - Either 'native' or 'partman'.

    • native - Use the native partitioning methods that are built into PostgreSQL 10+.
    • partman - Create a trigger-based partition set; this is not available in YugabyteDB.

  • p_interval – The time interval or integer range for each partition. For example, daily, hourly, monthly, and so on.

  • p_premake – The number of partitions to create in advance to support new inserts.

To learn more, see Creation Functions in the pg_partman documentation.

part_config table

The part_config table stores all configuration data for partition sets managed by pg_partman. A new row for the partition table is added after calling the create_parent() function.

The part_config table can be used to make decisions about:

  • What new partitions to create.
  • Which old partitions to drop or detach from the partition set.
  • What table updates are required.
For more information, see Tables in the pg_partman documentation

An example is as follows:

SELECT parent_table, control, partition_interval, premake, retention FROM partman.part_config;

 parent_table  |  control   | partition_interval | premake | retention
---------------+------------+--------------------+---------+-----------
 public.orders | order_date | 1 mon              |       5 |

You can update the part_config table as follows:

UPDATE partman.part_config
SET partition_interval = 2 months
WHERE parent_table = 'public.orders';

Maintain partitions using pg_cron

pg_cron is a cron-based job scheduler for PostgreSQL that runs inside a database as an extension.

You can schedule the pg_partman run_maintenance() function, which automatically creates child tables and drops old child partitions, using pg_cron. For example:

  1. Load the pg_cron extension as follows:

    CREATE EXTENSION pg_cron;

  2. Update the part_config table retention-related fields as follows:

    UPDATE partman.part_config
SET retention = '3 months',
retention_keep_table=true
WHERE parent_table = 'public.orders';
    • retention - Sets the maximum retention for the table.
    • retention_keep_table - When set to true, specifies that the table is only detached from the partition set and isn't deleted automatically.

  3. Schedule the run_maintenance() call using the cron.schedule procedure as follows:

    SELECT cron.schedule(
    'Run maintenance job',
    '10 seconds',
    'SELECT partman.run_maintenance()'
);

  4. Monitor the scheduled maintenance job by querying the cron.job table as follows:

    SELECT jobid, schedule, command, jobname FROM cron.job;

    
 jobid |  schedule  |             command              |       jobname
-------+------------+----------------------------------+----------+-------------
     1 | 10 seconds | SELECT partman.run_maintenance() | Run maintenance job

Limitations

The pg_partman extension has the following limitations in YugabyteDB.

These limitations ensure that pg_partman features align with the capabilities and architecture of YugabyteDB, maintaining system performance and stability. You should adjust your use of partitioning strategies accordingly to adhere to these constraints.

Supported partitioning methods

Only native partitioning is supported in YugabyteDB. Non-native partitioning, which uses table inheritance and triggers to route data to the appropriate child tables, is not supported because YugabyteDB does not support table inheritance.

Versions of pg_partman later than v4.7.4 have deprecated non-native partitioning, so migrating partition sets from non-native to native partitioning methods can be challenging.

The following example shows an unsupported operation using non-native partitioning:

CREATE SCHEMA partman;

CREATE EXTENSION pg_partman WITH SCHEMA partman;

CREATE TABLE orders (
  order_id SERIAL,
  order_date DATE NOT NULL,
  customer_id INT
) PARTITION BY RANGE (order_date);

CREATE EXTENSION pg_partman WITH SCHEMA partman;

CREATE TABLE orders (
  order_id SERIAL,
  order_date DATE NOT NULL,
  customer_id INT
) PARTITION BY RANGE (order_date);

SELECT partman.create_parent( p_parent_table => 'public.orders',
  p_control => 'order_date',
  p_type => 'partman',
  p_interval =>'monthly',
  p_premake => 5
);

ERROR:  partman is not a valid partitioning type for pg_partman

ACCESS EXCLUSIVE LOCK

The pg_partman create_parent() function requires an access exclusive lock on the parent table to create new child partitions. Currently, access exclusive locks are not supported in YugabyteDB, and are disabled in this function.

Advisory locks

Advisory locks, used in some pg_partman functions to create or drop/delete partitioned tables, are not currently supported in pg_partman in YugabyteDB. Attempts to acquire these locks are disabled.

Background worker process

The pg_partman background worker process, which automates partition maintenance without the need of an external scheduler, is disabled in favor of using pg_cron to manage such tasks externally.

undo_partition function

The undo_partition() function, which moves data from child tables back to a target table, is disabled.

As part of undo_partition(), all data from child partitions is moved out to the target table and after that the child table is detached from the parent table. This is done in an iterative manner, looping through each child.

undo_partition() is disabled because YugabyteDB does not currently support transactional DDL operations (the DMLs (deleting data from child tables) and DDLs (detaching child tables) will cause conflicts), which are required for this functionality.

For example:

SELECT partman.undo_partition(p_parent_table => 'public.orders');

ERROR:  undo_partition not supported yet in YugabyteDB

Default partition creation

Creation and use of default partitions are disabled. If a default partition is created, partition_data_proc and run_maintenance() operations will exit early without performing any operation.

For example:

SELECT partman.create_parent( p_parent_table => 'public.orders',
  p_control => 'order_date',
  p_type => 'native',
  p_interval =>'monthly',
  p_premake => 5
);

  create_parent
---------------
  t
(1 row)

\d

                      List of relations
  Schema |        Name         |       Type        |  Owner
--------+---------------------+-------------------+----------
  public | orders              | partitioned table | yugabyte
  public | orders_order_id_seq | sequence          | yugabyte
  public | orders_p2024_06     | table             | yugabyte
  public | orders_p2024_07     | table             | yugabyte
  public | orders_p2024_08     | table             | yugabyte
  public | orders_p2024_09     | table             | yugabyte
  public | orders_p2024_10     | table             | yugabyte
  public | orders_p2024_11     | table             | yugabyte
  public | orders_p2024_12     | table             | yugabyte
  public | orders_p2025_01     | table             | yugabyte
  public | orders_p2025_02     | table             | yugabyte
  public | orders_p2025_03     | table             | yugabyte
  public | orders_p2025_04     | table             | yugabyte
(13 rows)

No default partition created

If you try to create a default partition explicitly and call run_maintenance(), the run maintenance job is skipped as follows:

CREATE TABLE orders_default PARTITION OF orders DEFAULT;
SELECT partman.run_maintenance('public.orders');

NOTICE:  Skip run maintenace job for table public.orders as it has default table attached
  run_maintenance
-----------------

(1 row)

Colocated databases

Registration of a partitioned table for maintenance by pg_partman is not allowed if the table belongs to a colocated database.

For example:

yugabyte=# CREATE DATABASE mo WITH colocation=true;
yugabyte=# \c mo

mo=# SELECT create_parent( p_parent_table => 'public.orders',
  p_control => 'order_date',
  p_type => 'native',
  p_interval =>'monthly',
  p_premake => 5);

mo=# CREATE extension pg_partman;

mo=# SELECT create_parent( p_parent_table => 'public.orders',
  p_control => 'order_date',
  p_type => 'native',
  p_interval =>'monthly',
  p_premake => 5);

ERROR:  Partition table public.orders is a colocated table hence registering it to pg_partman maintenance is not supported

xCluster

Depending on the type of xCluster deployment, pg_partman may be used.

Note that if you are using pg_cron to manage tasks:

  • In v2025.1.0 or earlier, or if you are using semi-automatic or manual mode, you must install pg_cron on a separate database that is not part of the xCluster configuration.
  • In v2025.1.1 or later in automatic mode, you can install pg_cron on the same database.

For more information on xCluster limitations, refer to Limitations.

Transactional xCluster and xCluster DR

Automatic mode

The pg_partman maintenance cron job can only be enabled on the xCluster primary. Disable it on the xCluster standby.

During disaster recovery switchover (or failover and repair):

  1. Disable the pg_partman cron job on the original xCluster primary before initiating switchover.
  2. After switchover or failover, enable the pg_partman cron job on the new primary.

In v2025.1.1 and later, pg_cron will only execute on the Primary universe. On switchover, pg_cron will automatically switch over to the new Primary universe as well.

Semi-automatic mode

At setup, do the following:

  1. On the primary universe, enable the pg_partman extension and the pg_audit extension.
  2. On the standby universe, enable the pg_partman extension, and disable the pg_partman maintenance cron job.

During normal operations, as DDLs occur on the primary universe, do the following:

  1. Monitor the pg_audit log on the primary universe to detect partition-related DDLs.
  2. When any partition-related DDLs are detected, manually run them also on the standby universe; this must be done within the WAL log retention time (which is 4 hours by default).

Manual DDL change handling mode

pg_partman is not supported.

Non-transactional xCluster (including bi-directional)

pg_partman is not recommended.

Because pg_partman creates and drops tables, if you were to try to run pg_partman on both universes, the partitions might not be created at the same time on both sides. Even if they were identical, manual work is needed to add the new tables and remove dropped tables from the xCluster configuration.

If you were to try to run pg_partman on just one side, then any tables created or dropped by pg_partman would have to be created or dropped on the target, which would require difficult manual administration.

Although not recommended, it is possible to use pg_partman using the following steps:

Setup

  1. On one universe (call this universe A):

    • Enable the pg_partman extension.
    • Enable the pg_audit extension.

    Note: in a uni-directional replication configuration, choose universe A to be your source universe. In a bi-directional replication configuration, both universes act as source and target (usually for distinctly different tables, however).

  2. On the other universe (call this universe B):

    • Enable the pg_partman extension.
    • Disable the pg_partman maintenance cron job.

Operation

During normal operations, as DDLs occur on the source universe, monitor the pg_audit log (on the source universe) to detect partition-related DDLs.

When you detect partition-related DDLs, follow the instructions in Handling DDL changes to issue the same DDL command on the replica universe and include the table in xCluster replication.

Note that the sequence of operations can vary by DDL command (for example, CREATE partition and DROP partition require different follow-up actions in different orders).