Unable to enable citus_columnar on Azure PostgreSQL Elastic Clusters

Question

Unable to enable citus_columnar on Azure PostgreSQL Elastic Clusters

Adela M B 20

Hello,

I am using Azure Database for PostgreSQL Flexible Server – Elastic Clusters (PostgreSQL 17 + Citus 13.2).

According to the open-source Citus documentation and the previous Azure Cosmos DB for PostgreSQL (Hyperscale) service, columnar storage is a supported feature via the citus_columnar extension (or the USING columnar table access method).

However, on my Elastic Cluster I am currently unable to enable it. See details below.

SELECT * FROM pg_available_extensions WHERE name ILIKE '%columnar%' OR name ILIKE '%citus%';

this indicates that citus_columnar may be available for installation.

User's image

However, when I try to create the extension with CREATE EXTENSION citus_columnar; I receive the following error:

ERROR: extension "citus_columnar" is not allow-listed for "azure_pg_admin" users in Azure Database for PostgreSQL HINT: to learn how to allow an extension or see the list of allowed extensions, please refer to https://go.microsoft.com/fwlink/?linkid=2301063

The extension citus_columnar does not appear in the list of allowed extensions, and there is currently no way to allow-list it.

My questions:

Is citus_columnar / columnar storage currently supported on Elastic Clusters? If it is supposed to be supported, could you please enable it or tell me the correct way to activate it?
If not, is it planned, and is there a timeline?

Cluster details (if useful):

Region: Sweden Central
PostgreSQL version: 17
Number of nodes: 1
Approximate creation date: 2/9/2026

Thank you in advance for the clarification.

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Answer 1

The behaviour you are seeing suggests that citus_columnar is currently not exposed as a supported feature on azure db for PostgreSQL Flexible Server Elastic Clusters.

A key point is that the presence of citus_columnar in pg_available_extensions only indicates that the extension metadata exists in the PostgreSQL image. It does not guarantee that the extension is customer-installable on the managed service. [learn.microsoft.com]

The decisive indicator is the error: ERROR: extension "citus_columnar" is not allow-listed for "azure_pg_admin"

This is an Azure service-level restriction rather than a PostgreSQL or Citus permission issue. [learn.microsoft.com]

It is also worth distinguishing between: CREATE EXTENSION citus_columnar;

&

CREATE TABLE mytable (...) USING columnar;

Open-source Citus supports columnar storage, but the underlying columnar access method must be enabled by the service. If citus_columnar is not allow-listed, customers cannot enable that capability themselves. [learn.microsoft.com]

Based on the currently published Elastic Cluster documentation and the behaviour you observed:

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One additional point: although columnar tables were available in the retired Azure Cosmos DB for PostgreSQL service, that does not necessarily imply feature parity with Azure Database for PostgreSQL Elastic Clusters. Managed-service capabilities can differ from those available in upstream Citus or predecessor Azure offerings. [learn.microsoft.com]

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