---
title: "ClickHouse release 26.9"
description: "ClickHouse 26.9 ships with 56 new features, 135 performance optimizations, and 464 bug fixes. Among the highlights are conditional LIMIT boundaries that control output based on ordered stream values, incremental refreshes for append-only materialized views, and disk spilling for high-cardinality DISTINCT queries that automatically spills when memory usage reaches half the limit. The CREATE TOKEN feature issues time-limited credentials with a default lifetime of 30 minutes and restricted privileges, reducing the impact of leaked keys. Arithmetic operations between DateTime and Time types now support configurable overflow behaviors—throw, saturate, or ignore. PromQL support expands in a private preview on ClickHouse Cloud, bracket syntax simplifies JSON subcolumn access, and queries for min, max, and count receive performance improvements."
---

# ClickHouse release 26.9

[Clickhouse](https://yomu.fyi/company/clickhouse) · Sep 23, 2026

**Type:** Announcement

## Summary

ClickHouse 26.9 ships with 56 new features, 135 performance optimizations, and 464 bug fixes. Among the highlights are conditional LIMIT boundaries that control output based on ordered stream values, incremental refreshes for append-only materialized views, and disk spilling for high-cardinality DISTINCT queries that automatically spills when memory usage reaches half the limit. The CREATE TOKEN feature issues time-limited credentials with a default lifetime of 30 minutes and restricted privileges, reducing the impact of leaked keys. Arithmetic operations between DateTime and Time types now support configurable overflow behaviors—throw, saturate, or ignore. PromQL support expands in a private preview on ClickHouse Cloud, bracket syntax simplifies JSON subcolumn access, and queries for min, max, and count receive performance improvements.

## Context

A blog post announcing ClickHouse 26.9, detailing 56 new features, 135 performance optimizations, and 464 bug fixes, with technical descriptions of conditional LIMIT boundaries, incremental materialized views, disk spilling for DISTINCT, time-limited tokens, DateTime-Time arithmetic, PromQL preview, and JSON bracket syntax.

## Takeaways

- ClickHouse 26.9 introduces conditional LIMIT boundaries that start and stop output based on values in the ordered result stream.
- CREATE TOKEN allows users to generate time-limited credentials with restricted privileges, with a default lifetime of 30 minutes.
- Disk spilling for DISTINCT queries automatically triggers when memory usage reaches half the limit via max\_bytes\_ratio\_before\_external\_distinct set to 0.5.

## FAQ

### How does disk spilling work for DISTINCT queries?

When max\_bytes\_ratio\_before\_external\_distinct is set to 0.5, DISTINCT queries automatically spill partially aggregated data to disk once memory usage reaches half the max\_memory\_usage limit, allowing handling of high-cardinality data without exceeding memory.

### What overflow behaviors are available for DateTime-Time arithmetic?

The date\_time\_overflow\_behavior setting controls overflow when DateTime-Time arithmetic results are out of range: 'throw' raises an exception, 'saturate' clamps to the type's boundary, and 'ignore' silently wraps around to the minimum value.

### How does CREATE TOKEN restrict privileges?

CREATE TOKEN issues time-limited credentials that restrict privileges to a subset of the user's existing grants. The token never grants more than the user already has and expires after a specified interval (default 30 minutes).

**Tags:** [ClickHouse](https://yomu.fyi/topic/clickhouse), [JSON](https://yomu.fyi/topic/json), [Performance](https://yomu.fyi/topic/performance), [Security](https://yomu.fyi/topic/security), [Time Series](https://yomu.fyi/topic/time-series)

- Source: [Clickhouse](https://clickhouse.com/blog/clickhouse-release-26-09)
- Source URL: https://clickhouse.com/blog/clickhouse-release-26-09
- Ingested by Yomu: 2026-09-24T12:00:09.571Z

[Read original post](https://clickhouse.com/blog/clickhouse-release-26-09)