ClickHouse/clickhouse-docs-embeddings huggingface dataset:
2023 Changelog

#### Build/Testing/Packaging Improvement[​](#buildtestingpackaging-improvement-10 "Direct link to Build/Testing/Packaging Improvement")

- Introduce GWP-ASan implemented by the LLVM runtime. This closes [#27039](https://github.com/ClickHouse/ClickHouse/issues/27039). [#45226](https://github.com/ClickHouse/ClickHouse/pull/45226) ([Han Fei](https://github.com/hanfei1991)).
- We want to make our tests less stable and more flaky: add randomization for merge tree settings in tests. [#38983](https://github.com/ClickHouse/ClickHouse/pull/38983) ([Anton Popov](https://github.com/CurtizJ)).
- Enable the HDFS support in PowerPC and which helps to fixes the following functional tests 02113\_hdfs\_assert.sh, 02244\_hdfs\_cluster.sql and 02368\_cancel\_write\_into\_hdfs.sh. [#44949](https://github.com/ClickHouse/ClickHouse/pull/44949) ([MeenaRenganathan22](https://github.com/MeenaRenganathan22)).
- Add systemd.service file for clickhouse-keeper. Fixes [#44293](https://github.com/ClickHouse/ClickHouse/issues/44293). [#45568](https://github.com/ClickHouse/ClickHouse/pull/45568) ([Mikhail f. Shiryaev](https://github.com/Felixoid)).
- ClickHouse's fork of poco was moved from "contrib/" to "base/poco/". [#46075](https://github.com/ClickHouse/ClickHouse/pull/46075) ([Robert Schulze](https://github.com/rschu1ze)).
- Add an option for `clickhouse-watchdog` to restart the child process. This does not make a lot of use. [#46312](https://github.com/ClickHouse/ClickHouse/pull/46312) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- If the environment variable `CLICKHOUSE_DOCKER_RESTART_ON_EXIT` is set to 1, the Docker container will run `clickhouse-server` as a child instead of the first process, and restart it when it exited. [#46391](https://github.com/ClickHouse/ClickHouse/pull/46391) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Fix Systemd service file. [#46461](https://github.com/ClickHouse/ClickHouse/pull/46461) ([SuperDJY](https://github.com/cmsxbc)).
- Raised the minimum Clang version needed to build ClickHouse from 12 to 15. [#46710](https://github.com/ClickHouse/ClickHouse/pull/46710) ([Robert Schulze](https://github.com/rschu1ze)).
- Upgrade Intel QPL from v0.3.0 to v1.0.0 2. Build libaccel-config and link it statically to QPL library instead of dynamically. [#45809](https://github.com/ClickHouse/ClickHouse/pull/45809) ([jasperzhu](https://github.com/jinjunzh)).

#### Bug Fix (user-visible misbehavior in official stable release)[​](#bug-fix-user-visible-misbehavior-in-official-stable-release "Direct link to Bug Fix (user-visible misbehavior in official stable release)")
2023 Changelog

### ClickHouse release 23.1, 2023-01-26. [Presentation](https://presentations.clickhouse.com/2023-release-23.1/), [Video](https://www.youtube.com/watch?v=zYSZXBnTMSE)[​](#231 "Direct link to 231")

### ClickHouse release 23.1[​](#clickhouse-release-231 "Direct link to ClickHouse release 23.1")

#### Upgrade Notes[​](#upgrade-notes-2 "Direct link to Upgrade Notes")

- The `SYSTEM RESTART DISK` query becomes a no-op. [#44647](https://github.com/ClickHouse/ClickHouse/pull/44647) ([alesapin](https://github.com/alesapin)).
- The `PREALLOCATE` option for `HASHED`/`SPARSE_HASHED` dictionaries becomes a no-op. [#45388](https://github.com/ClickHouse/ClickHouse/pull/45388) ([Azat Khuzhin](https://github.com/azat)). It does not give significant advantages anymore.
- Disallow `Gorilla` codec on columns of non-Float32 or non-Float64 type. [#45252](https://github.com/ClickHouse/ClickHouse/pull/45252) ([Robert Schulze](https://github.com/rschu1ze)). It was pointless and led to inconsistencies.
- Parallel quorum inserts might work incorrectly with `*MergeTree` tables created with the deprecated syntax. Therefore, parallel quorum inserts support is completely disabled for such tables. It does not affect tables created with a new syntax. [#45430](https://github.com/ClickHouse/ClickHouse/pull/45430) ([Alexander Tokmakov](https://github.com/tavplubix)).
- Use the `GetObjectAttributes` request instead of the `HeadObject` request to get the size of an object in AWS S3. This change fixes handling endpoints without explicit regions after updating the AWS SDK, for example. [#45288](https://github.com/ClickHouse/ClickHouse/pull/45288) ([Vitaly Baranov](https://github.com/vitlibar)). AWS S3 and Minio are tested, but keep in mind that various S3-compatible services (GCS, R2, B2) may have subtle incompatibilities. This change also may require you to adjust the ACL to allow the `GetObjectAttributes` request.
- Forbid paths in timezone names. For example, a timezone name like `/usr/share/zoneinfo/Asia/Aden` is not allowed; the IANA timezone database name like `Asia/Aden` should be used. [#44225](https://github.com/ClickHouse/ClickHouse/pull/44225) ([Kruglov Pavel](https://github.com/Avogar)).
- Queries combining equijoin and constant expressions (e.g., `JOIN ON t1.x = t2.x AND 1 = 1`) are forbidden due to incorrect results. [#44016](https://github.com/ClickHouse/ClickHouse/pull/44016) ([Vladimir C](https://github.com/vdimir)).

#### New Feature[​](#new-feature-11 "Direct link to New Feature")
2023 Changelog

- Fix `output_format_pretty_row_numbers` does not preserve the counter across the blocks. Closes [#44815](https://github.com/ClickHouse/ClickHouse/issues/44815). [#44832](https://github.com/ClickHouse/ClickHouse/pull/44832) ([flynn](https://github.com/ucasfl)).
- Don't report errors in `system.errors` due to parts being merged concurrently with the background cleanup process. [#44874](https://github.com/ClickHouse/ClickHouse/pull/44874) ([Raúl Marín](https://github.com/Algunenano)).
- Optimize and fix metrics for Distributed async INSERT. [#44922](https://github.com/ClickHouse/ClickHouse/pull/44922) ([Azat Khuzhin](https://github.com/azat)).
- Added settings to disallow concurrent backups and restores resolves [#43891](https://github.com/ClickHouse/ClickHouse/issues/43891) Implementation: \* Added server-level settings to disallow concurrent backups and restores, which are read and set when BackupWorker is created in Context. \* Settings are set to true by default. \* Before starting backup or restores, added a check to see if any other backups/restores are running. For internal requests, it checks if it is from the self node using backup\_uuid. [#45072](https://github.com/ClickHouse/ClickHouse/pull/45072) ([SmitaRKulkarni](https://github.com/SmitaRKulkarni)).
- Add `<storage_policy>` config parameter for system logs. [#45320](https://github.com/ClickHouse/ClickHouse/pull/45320) ([Stig Bakken](https://github.com/stigsb)).
2023 Changelog

#### Build/Testing/Packaging Improvement[​](#buildtestingpackaging-improvement-11 "Direct link to Build/Testing/Packaging Improvement")

- Statically link with the `skim` library (it is written in Rust) for fuzzy search in clickhouse client/local history. [#44239](https://github.com/ClickHouse/ClickHouse/pull/44239) ([Azat Khuzhin](https://github.com/azat)).
- We removed support for shared linking because of Rust. Actually, Rust is only an excuse for this removal, and we wanted to remove it nevertheless. [#44828](https://github.com/ClickHouse/ClickHouse/pull/44828) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Remove the dependency on the `adduser` tool from the packages, because we don't use it. This fixes [#44934](https://github.com/ClickHouse/ClickHouse/issues/44934). [#45011](https://github.com/ClickHouse/ClickHouse/pull/45011) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- The `SQLite` library is updated to the latest. It is used for the SQLite database and table integration engines. Also, fixed a false-positive TSan report. This closes [#45027](https://github.com/ClickHouse/ClickHouse/issues/45027). [#45031](https://github.com/ClickHouse/ClickHouse/pull/45031) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- CRC-32 changes to address the WeakHash collision issue in PowerPC. [#45144](https://github.com/ClickHouse/ClickHouse/pull/45144) ([MeenaRenganathan22](https://github.com/MeenaRenganathan22)).
- Update aws-c\* submodules [#43020](https://github.com/ClickHouse/ClickHouse/pull/43020) ([Vitaly Baranov](https://github.com/vitlibar)).
- Automatically merge green backport PRs and green approved PRs [#41110](https://github.com/ClickHouse/ClickHouse/pull/41110) ([Mikhail f. Shiryaev](https://github.com/Felixoid)).
- Introduce a [website](https://aretestsgreenyet.com/) for the status of ClickHouse CI. [Source](https://github.com/ClickHouse/aretestsgreenyet).

#### Bug Fix[​](#bug-fix "Direct link to Bug Fix")
2023 Changelog

## [Changelog for 2022](/docs/whats-new/changelog/2022)[​](#changelog-for-2022 "Direct link to changelog-for-2022")

- [Table of Contents](#table-of-contents)- ClickHouse release 23.12, 2023-12-28. Presentation, Video- ClickHouse release 23.11, 2023-12-06. Presentation, Video- ClickHouse release 23.10, 2023-11-02. Presentation, Video- ClickHouse release 23.9, 2023-09-28. Presentation, Video- ClickHouse release 23.8 LTS, 2023-08-31. Presentation, Video- ClickHouse release 23.7, 2023-07-27. Presentation, Video- ClickHouse release 23.6, 2023-06-29. Presentation, Video- ClickHouse release 23.5, 2023-06-08. Presentation, Video- ClickHouse release 23.4, 2023-04-26. Presentation, Video- ClickHouse release 23.3 LTS, 2023-03-30. Presentation, Video- ClickHouse release 23.2, 2023-02-23. Presentation, Video- ClickHouse release 23.1, 2023-01-26. Presentation, Video- [ClickHouse release 23.1](#clickhouse-release-231)- [Changelog for 2022](#changelog-for-2022)

Was this page helpful?
title_wip

Learn how to use ClickHouse through guides, reference documentation, and videos

[Quick Start

Get Started with Cloud](/docs/cloud/get-started/cloud-quick-start)[Install Locally

Get Started with OSS](/docs/getting-started/quick-start/oss)

Search Documentation

[Search`Ctrl``K`](/docs/search)

Connect to ClickHouse

Connect your application to ClickHouse in minutes

[View All Clients and Drivers →](/docs/interfaces/overview)

[ClickHouse CLI](/docs/interfaces/cli)[Cloud SQL Console](/docs/cloud/get-started/sql-console)[![Node.js logo](/docs/images/logo-nodejs.svg)

Node.js](/docs/integrations/javascript)

[![Java logo](/docs/images/logo-java.svg)

Java](/docs/integrations/java)[![Python logo](/docs/images/logo-python.svg)

Python](/docs/integrations/python)[![Go logo](/docs/images/logo-go.svg)

Go](/docs/integrations/go)

Migrate to ClickHouse

Load data from other databases, data warehouses, and object storage

[View All Integrations →](/docs/integrations)

[![Snowflake logo](/docs/images/logo-snowflake.svg)

Snowflake](/docs/migrations/snowflake)[![BigQuery logo](/docs/images/logo-bigquery.svg)

BigQuery](/docs/migrations/bigquery)[![Redshift logo](/docs/images/logo-redshift.svg)

Redshift](/docs/integrations/redshift)

[![Postgres logo](/docs/images/logo-postgres.svg)

Postgres](/docs/integrations/postgresql)[![MySQL logo](/docs/images/logo-mysql.svg)

MySQL](/docs/integrations/mysql)[![S3 logo](/docs/images/logo-s3.svg)

S3](/docs/integrations/s3)

Deploy ClickHouse

Deploy ClickHouse to the cloud or your own infrastructure

[Cloud](https://clickhouse.com/cloud)[Node Deployment](/docs/architecture/introduction)[Cluster Deployment](/docs/architecture/cluster-deployment)[ClickHouse Operator](/docs/clickhouse-operator/overview)

Other Resources

[Contact Support](https://clickhouse.com/support/program)[Changelog](/docs/whats-new/changelog)[Sample Datasets](/docs/getting-started/example-datasets)
title_wip

[Edit this page](https://github.com/ClickHouse/clickhouse-docs/blob/main/docs/about-us/index.md)

In this section of the docs you'll find information about ClickHouse. Refer to
the table of contents below for a list of pages in this section of the docs.

|  |  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Page Description|  |  |  |  |  |  |  |  |  |  | | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | | [Adopters](/docs/about-us/adopters) A list of companies using ClickHouse and their success stories, assembled from public sources|  |  |  |  |  |  |  |  | | --- | --- | --- | --- | --- | --- | --- | --- | | [Support](/docs/about-us/support) An introduction to ClickHouse Cloud support services and their mission.|  |  |  |  |  |  | | --- | --- | --- | --- | --- | --- | | [Beta features and experimental features](/docs/beta-and-experimental-features) Learn about how ClickHouse uses "Beta" and "Experimental" labels to distinguish between officially supported and early-stage, unsupported features due to varied development speeds from community contributions.|  |  |  |  | | --- | --- | --- | --- | | [Cloud service](/docs/about-us/cloud) Discover ClickHouse Cloud - a fully managed service that allows you to spin up open-source ClickHouse databases and offers benefits like fast time to value, seamless scaling, and serverless operations.|  |  | | --- | --- | | [ClickHouse history](/docs/about-us/history) Learn more about the history of ClickHouse. | | | | | | | | | | | |

Was this page helpful?
title_wip

[Edit this page](https://github.com/ClickHouse/clickhouse-docs/blob/main/docs/about-us/cloud.md)

ClickHouse Cloud is the cloud offering created by the original creators of the popular open-source OLAP database ClickHouse.
You can experience ClickHouse Cloud by [starting a free trial](https://console.clickhouse.cloud/signUp).

## ClickHouse Cloud benefits[​](#clickhouse-cloud-benefits "Direct link to ClickHouse Cloud benefits")

Some of the benefits of using ClickHouse Cloud are described below:

- **Fast time to value**: Start building instantly without having to size and scale your cluster.
- **Seamless scaling**: Automatic scaling adjusts to variable workloads so you don't have to over-provision for peak usage.
- **Serverless operations**: Sit back while we take care of sizing, scaling, security, reliability, and upgrades.
- **Transparent pricing**: Pay only for what you use, with resource reservations and scaling controls.
- **Total cost of ownership**: Best price / performance ratio and low administrative overhead.
- **Broad ecosystem**: Bring your favorite data connectors, visualization tools, SQL and language clients with you.

## What version of ClickHouse does ClickHouse Cloud use?[​](#what-version-of-clickhouse-does-clickhouse-cloud-use "Direct link to What version of ClickHouse does ClickHouse Cloud use?")

Clickhouse Cloud periodically upgrades your service to newer versions that include fixes, new features and performance improvements. After publishing a core database version in the open source, we do additional validation in our cloud staging environment, which typically takes 6-8 weeks before rolling out to production. The rollout is phased out by cloud service provider, service type, and region.

You can specify the upgrade schedule for your ClickHouse Cloud service by subscribing to a specific release channel. For example, we offer a ["Fast" Release Channel](/docs/manage/updates#fast-release-channel-early-upgrades) for subscribing to updates ahead of the regular release schedule, as well as a ["Slow" Release Channel](/docs/manage/updates#slow-release-channel-deferred-upgrades) and other more granular scheduling options for deferred upgrades.

For an overview of ClickHouse Cloud's upgrade process, including backwards compatibility guarantees, see the reference documentation for [Upgrades](/docs/manage/updates).

- [ClickHouse Cloud benefits](#clickhouse-cloud-benefits)- [What version of ClickHouse does ClickHouse Cloud use?](#what-version-of-clickhouse-does-clickhouse-cloud-use)

Was this page helpful?
Distinctive features of ClickHouse

For more information, see the section [Data replication](/docs/engines/table-engines/mergetree-family/replication).

## Role-Based Access Control[​](#role-based-access-control "Direct link to Role-Based Access Control")

ClickHouse implements user account management using SQL queries and allows for [role-based access control configuration](/docs/operations/access-rights) similar to what can be found in the ANSI SQL standard and popular relational database management systems.

## Features that can be considered disadvantages[​](#clickhouse-features-that-can-be-considered-disadvantages "Direct link to Features that can be considered disadvantages")

1. No full-fledged transactions.
2. Lack of ability to modify or delete already inserted data with a high rate and low latency. There are batch deletes and updates available to clean up or modify data, for example, to comply with [GDPR](https://gdpr-info.eu).
3. The sparse index makes ClickHouse not so efficient for point queries retrieving single rows by their keys.

- [True column-oriented database management system](#true-column-oriented-database-management-system)- [Data compression](#data-compression)- [Disk storage of data](#disk-storage-of-data)- [Parallel processing on multiple cores](#parallel-processing-on-multiple-cores)- [Distributed processing on multiple servers](#distributed-processing-on-multiple-servers)- [SQL support](#sql-support)- [Vector computation engine](#vector-engine)- [Real-time data inserts](#real-time-data-updates)- [Primary indexes](#primary-index)- [Secondary indexes](#secondary-indexes)- [Suitable for online queries](#suitable-for-online-queries)- [Support for approximated calculations](#support-for-approximated-calculations)- [Adaptive join algorithm](#adaptive-join-algorithm)- [Data replication and data integrity support](#data-replication-and-data-integrity-support)- [Role-Based Access Control](#role-based-access-control)- [Features that can be considered disadvantages](#clickhouse-features-that-can-be-considered-disadvantages)

Was this page helpful?
ClickHouse Cloud support services

[Edit this page](https://github.com/ClickHouse/clickhouse-docs/blob/main/docs/about-us/support.md)

ClickHouse provides support services for our ClickHouse Cloud users and customers. Our objective is a support services team that represents the ClickHouse product – unparalleled performance, ease of use, and exceptionally fast, high-quality results. For details, [visit our ClickHouse Support Program](https://clickhouse.com/support/program/) page.

[Login to the Cloud console](https://console.clickhouse.cloud/support) and select **Help -> Support** from the menu options to open a new support case and view the status of your submitted cases.

You can also subscribe to our [status page](https://status.clickhouse.com) to get notified quickly about any incidents affecting our platform.

Note

Please note that only subscription customers have a service level agreement on support incidents. If you're not currently a ClickHouse Cloud user – while we will try to answer your question, we'd encourage you to go instead to one of our community resources:

- [ClickHouse community Slack channel](https://clickhouse.com/slack)
- [Other community options](https://github.com/ClickHouse/ClickHouse/blob/master/README.md#useful-links)

Was this page helpful?
Architecture Overview

- [ABSTRACT](#abstract)- [1 INTRODUCTION](#1-introduction)- [2 ARCHITECTURE](#2-architecture)- [3 STORAGE LAYER](#3-storage-layer)
        - [3.1 On-Disk Format](#3-1-on-disk-format)- [3.2 Data Pruning](#3-2-data-pruning)- [3.3 Merge-time Data Transformation](#3-3-merge-time-data-transformation)- [3.4 Updates and Deletes](#3-4-updates-and-deletes)- [3.5 Idempotent Inserts](#3-5-idempotent-inserts)- [3.6 Data Replication](#3-6-data-replication)- [3.7 ACID Compliance](#3-7-acid-compliance)- [4 QUERY PROCESSING LAYER](#4-query-processing-layer)
          - [4.1 SIMD Parallelization](#4-1-simd-parallelization)- [4.2 Multi-Core Parallelization](#4-2-multi-core-parallelization)- [4.3 Multi-Node Parallelization](#4-3-multi-node-parallelization)- [4.4 Holistic Performance Optimization](#4-4-holistic-performance-optimization)- [4.5 Workload Isolation](#4-5-workload-isolation)- [5 INTEGRATION LAYER](#5-integration-layer)- [6 PERFORMANCE AS A FEATURE](#6-performance-as-a-feature)
            - [6.1 Built-in Performance Analysis Tools](#6-1-built-in-performance-analysis-tools)- [6.2 Benchmarks](#6-2-benchmarks)- [7 RELATED WORK](#7-related-work)- [8 CONCLUSION AND OUTLOOK](#8-conclusion-and-outlook)- [ACKNOWLEDGMENTS](#acknowledgements)- [REFERENCES](#references)

Was this page helpful?
Scaling

Unfortunately, our cluster isn't fault-tolerant. If one of the hosts fails, the
cluster is considered unhealthy and the query fails compared to the replicated
table we saw in the [previous example](/docs/architecture/replication) for which
we were able to insert data even when one of the hosts failed.

## Conclusion[​](#conclusion "Direct link to Conclusion")

The advantage of this cluster topology is that data gets distributed across
separate hosts and uses half the storage per node. More importantly, queries
are processed across both shards, which is more efficient in terms of memory
utilization and reduces I/O per host.

The main disadvantage of this cluster topology is, of course, that losing one of
the hosts renders us unable to serve queries.

In the [next example](/docs/architecture/cluster-deployment), we'll look at how to
set up a cluster with two shards and two replicas offering both scalability and
fault tolerance.

- [Prerequisites](#pre-requisites)- [Set up directory structure and test environment](#set-up)- [Configure ClickHouse nodes](#configure-clickhouse-servers)
      - [Server setup](#server-setup)- [User configuration](#user-config)- [Configure ClickHouse Keeper](#configure-clickhouse-keeper-nodes)
        - [Keeper setup](#configuration-explanation)- [Test the setup](#test-the-setup)- [Create a database](#creating-a-database)- [Create a table on the cluster](#creating-a-table)- [Create a distributed table](#create-distributed-table)- [Insert data into a distributed table](#inserting-data-into-distributed-table)- [Conclusion](#conclusion)

Was this page helpful?
Introduction

[Edit this page](https://github.com/ClickHouse/clickhouse-docs/blob/main/docs/deployment-guides/terminology.md)

The deployment examples in this section are based on the advice provided to ClickHouse users by
the ClickHouse Support and Services organization. These are working examples, and
we recommend that you try them and then adjust them to suit your needs. You may find
an example here that fits your requirements exactly.

We offer 'recipes' of a number of different topologies in the [example repo](https://github.com/ClickHouse/examples/tree/main/docker-compose-recipes/recipes)
and recommend taking a look at them if the examples in this section don't fit your
needs exactly.

## Terminology[​](#terminology "Direct link to Terminology")

### Replica[​](#replica "Direct link to Replica")

A copy of data. ClickHouse always has at least one copy of your data, and so the minimum number of **replicas** is one. This is an important detail, you may not be used to counting the original copy of your data as a replica, but that is the term used in ClickHouse code and documentation. Adding a second replica of your data provides fault tolerance.

### Shard[​](#shard "Direct link to Shard")

A subset of data. ClickHouse always has at least one shard for your data, so if you don't split the data across multiple servers, your data will be stored in one shard. Sharding data across multiple servers can be used to divide the load if you exceed the capacity of a single server. The destination server is determined by the **sharding key**, and is defined when you create the distributed table. The sharding key can be random or as an output of a [hash function](/docs/sql-reference/functions/hash-functions). The deployment examples involving sharding will use `rand()` as the sharding key, and will provide further information on when and how to choose a different sharding key.

### Distributed coordination[​](#distributed-coordination "Direct link to Distributed coordination")

ClickHouse Keeper provides the coordination system for data replication and distributed DDL queries execution. ClickHouse Keeper is compatible with Apache ZooKeeper.

- [Terminology](#terminology)
  - [Replica](#replica)- [Shard](#shard)- [Distributed coordination](#distributed-coordination)

Was this page helpful?