blocks|key|5515536|text|type|unstyled|depth|inlineStyleRanges|entityRanges|data|entityMap^0^^$0|@$1|2|3|-4|4|5|6|B|7|@]|8|@]|9|$]]]|A|$]]

A PostgreSQL cluster is an &quot;instance&quot; in Oracle parlance, (this is not the &quot;normal&quot; definition - see below) working on one machine.
You can have a PostgreSQL instance (cluster) with just one database, apart from the two templates (see below). To have a working system, you'll have 3 databases - two templates and one &quot;working&quot; database.
All of the PostgreSQL databases you create (i.e. company, organisation...) can have one or more schemas that you may also create. Any database can have multiple schemas - logical separation of functions - hr, accounting &amp;c., i.e within your overall company/organisation.
You'll get the <code>postgres</code> database and <code>template0</code> and <code>template1</code> by default. You should never touch <code>template0</code> - it can render your system inoperable - here's blog about <a href="https://dataschool.com/learn-sql/how-to-create-a-copy-of-a-database-in-postgresql/" rel="nofollow noreferrer">how to copy databases</a> from templates. The templates are &quot;skeletons&quot; - from which you create databases - all of the settings (from <code>postgresql.conf</code>) and system catalogs are there, but no ordinary tables! If you issue a <code>\d</code> from within template1, you'll receive the message: <code>Did not find any relations.</code>
<ul>
<li>On the same machine, you can have many clusters (PostgreSQL definition - see discussion of clusters below) as you want (within reason) using different ports. Production machines would typically use 5432 and dev/UAT machines might have a few clusters (i.e. instances) using different ports - running small test databases isn't very resource intensive!
</li>
<li>All of these databases can have their own (set of) schema(s) - so you could have (for example) 3 (PostgreSQL definition of) clusters running on ports 5432, 5433 and 5434, each with an hr schema, an accounting schema (as many schemas as you want - within reason).
</li>
</ul>
You are not obliged to create (a) schema(s) - it can be helpful for the logical separation of large databases into their constituent sections (c.f. hr/accts...)
<h2>Re clusters!</h2>
I think I see the reason for the confusion re clusters/databases/schemas!
PostgreSQL is very old - it <a href="https://en.wikipedia.org/wiki/Ingres_(database)" rel="nofollow noreferrer">derives from Ingres</a>:
<blockquote>
Ingres began as a research project at UC Berkeley, starting in the
early 1970s and ending in 1985.
</blockquote>
That's almost a full decade before Oracle's <a href="https://docs.oracle.com/cd/E11882_01/server.112/e40540/intro.htm#CNCPT88784" rel="nofollow noreferrer">first release</a> in 1979. It uses an older vocabulary than most systems' documentation.
Notice the terms that I've used:
<ul>
<li>System <code>catalogs</code> (rather than the more usual system &quot;tables&quot;)
</li>
<li><code>relations</code> (again, rather than &quot;tables&quot; - PostgreSQL makes a distinction between system tables (catalogs) and ordinary tables (relations)).
</li>
</ul>
PostgreSQL people are fond of using other terms i.e. <code>tuple</code> which has largely been replaced by &quot;record&quot; and/or &quot;row&quot; and <code>attribute</code> which has been replaced by &quot;column&quot; in other systems and in general usage. This change has possibly been driven by the ubiquity of spreadsheets!
These terms derive from <a href="https://en.wikipedia.org/wiki/Relational_calculus" rel="nofollow noreferrer">relational calculus</a> which derives from a paper written by <a href="https://en.wikipedia.org/wiki/Edgar_F._Codd" rel="nofollow noreferrer">Ted Codd</a> which uses <a href="https://dl.acm.org/doi/pdf/10.1145/362384.362685" rel="nofollow noreferrer">mathematical language</a>. The originator of the Ingres system was <a href="https://en.wikipedia.org/wiki/Michael_Stonebraker" rel="nofollow noreferrer">Michael Stonebraker</a>, an academic, hence the retention of (what might be considered) overly academic terms.
Nowadays, a &quot;<code>cluster</code>&quot; is <a href="https://en.wikipedia.org/wiki/Computer_cluster" rel="nofollow noreferrer">considered to be</a>:
<blockquote>
A computer cluster is a set of computers that work together so that
they can be viewed as a single system.
</blockquote>
This is not the PostgreSQL definition - possibly stemming from an older usage - I couldn't find any links for this, so it's speculation on my part!
The best definition of a cluster for PostgreSQL is PostgreSQL's <a href="https://www.postgresql.org/docs/current/creating-cluster.html" rel="nofollow noreferrer">own definition</a>:
<blockquote>
A database cluster is a collection of databases that is managed by a
single instance of a running database server.
</blockquote>
Note, there is nothing there about multiple machines - it is a single instance of a running database server! One can have many (PostgreSQL) clusters (i.e. instances) on a single machine - the PG definition is, in some ways, the inverse of what is more commonly accepted as the definition of a cluster (paraphrasing):
<pre><code>Normal definition: Many machines, one system
PostgreSQL definiton: Many systems, one machine
</code></pre>
<h2>Re HA</h2>
Doing replication with Master/Slave will automatically have two PostgreSQL clusters located on different machines - which may involve more than one database, but as I said, in PROD, it's normally dedicated to one database (alongside your skeletal templates, which you can't delete).
You'll have to have failover provision and then you have a cluster in the modern sense - many machines, one system. A full discussion of PostgreSQL High Availability would be an answer in itself and there are many different options - I would read what PostgreSQL themselves have to <a href="https://www.postgresql.org/docs/current/high-availability.html" rel="nofollow noreferrer">say about this</a> and also, <a href="https://postgrespro.com/blog/pgsql/5968057" rel="nofollow noreferrer">this post</a> by PostgresPro (big hitters in the PostgreSQL world) which provides a list of 4 systems which can do this job:
Finally, there is <a href="https://docs.percona.com/postgresql/11/solutions/high-availability.html" rel="nofollow noreferrer">Percona</a>, (and <a href="https://www.percona.com/ha-for-postgresql" rel="nofollow noreferrer">see here</a>) and <a href="https://severalnines.com/blog/how-deploy-postgresql-high-availability/" rel="nofollow noreferrer">SeveralNines</a> (a bit out of date at the time of writing - October 20th, 2022) - both big in the (Open Source) database world.
You need to read all of these posts, follow the links and ensure that you understand the pros and cons of each system and what compromises you and your stakeholders can/want to make (budget, <a href="https://www.druva.com/blog/understanding-rpo-and-rto/" rel="nofollow noreferrer">RTO/RPO</a>, expertise).
<h2>Last word on &quot;clusters&quot;:</h2>
Finally, and to add a bit of complication to the mix, there are now PostgreSQL systems that are &quot;natively&quot; distributed. There's <a href="https://www.timescale.com/products#how-it-works" rel="nofollow noreferrer">TimescaleDB</a> and <a href="https://www.citusdata.com/" rel="nofollow noreferrer">Citusdata</a> - which are &quot;distributed PostgreSQL&quot;. These work by sharding - i.e. different chunks of data on different machines, while maintaining a (user-specified, normally prime number) level of redundancy.
Their HA solutions appear to be cloud based (Citusdata is owned by Microsoft) - see <a href="https://docs.timescale.com/timescaledb/latest/how-to-guides/replication-and-ha/about-ha/" rel="nofollow noreferrer">here</a> (Timescale) and <a href="https://docs.citusdata.com/en/v7.2/cloud/availability.html" rel="nofollow noreferrer">here</a> Citus. It is worth nothing that both are based on the amazing PostgreSQL <a href="https://pgxn.org/" rel="nofollow noreferrer">system of extensions</a>! You might want to take a look there also.
Similar systems would be CockroachDB, Yugabyte and TiDB.
Finally, from another set of heavy hitters comes <a href="https://openproceedings.org/2019/conf/edbt/EDBT19_paper_360.pdf" rel="nofollow noreferrer">this definition</a> (top of page 2) of a cluster:
<blockquote>
A database cluster consists of N database instances running on N
physically separate machines sharing no components and connected to
each other by a network. Each instance contains a complete copy of the
data, and is able to start and maintain arbitrary point-in-time
snapshot transactions.
</blockquote>
So, these guys' definition is different to all of the previous ones... go figure...

Forgive my stupid question.
I want to know what are the differences between postgreSQL database cluster (1 server, N databases, N ports) vs one server hosting multiple databases (1 server, N databases, 1 port)?
I have read the clustering <a href="https://www.opsdash.com/blog/postgresql-cluster.html" rel="nofollow noreferrer">here</a> and also <a href="https://hevodata.com/learn/postgresql-cluster/" rel="nofollow noreferrer">here</a> and <a href="https://www.interdb.jp/pg/pgsql01.html" rel="nofollow noreferrer">this</a> too. I just don't get it. Even weirder to me (due to my lack of knowledge), on OpDash it says cluster can run different versions of postgres at the same time. :(
Any samples of database clustering usage in the real-world?
Suppose I want to do High Availibility with Master - Slave replication, do I need database clustering for this?
please enlighten me or point me to a direction/article.
Thank you

postgresql database cluster vs one server with many databases

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

文章

问答

视频

教程

学习中心

腾讯云实验室

直播

竞赛

腾讯云代码分析专区

腾讯iOA零信任安全管理系统专区

腾讯云架构师技术同盟交流圈

腾讯云数据库专区

腾讯云智能顾问专区

腾讯云原生专区

腾讯混元专区

腾讯云TCE专区

腾讯云Lighthouse专区

腾讯云HAI专区

腾讯云Edgeone专区

腾讯云存储专区

腾讯云智能专区

腾讯轻联专区 

腾讯云开发专区

TAPD专区

腾讯轻量云游戏服专区

EdgeOne AI 安全实战专区

腾讯云最具价值专家

腾讯云架构师技术同盟

腾讯云创作之星

腾讯云开发者先锋

腾讯云AI代码助手

云原生构建

TAPD 敏捷项目管理

Cloud Studio

SDK中心

API中心

命令行工具

功能1上新10个字符

功能2描述100个字符功能2描述100个字符功能2描述100个字符功能2描述100个字符功能2描述100个字符功能2描述100个字符功能2描述100个字符功能2描述100个字符功能2描述100个字符。

功能2上新100个字符功能2上新100个字符功能2上新100个字符功能2上新100个字符功能2上新100个字符功能2上新100个字符功能2上新100个字符功能2上新100个字符功能2上新100个字符。

功能5描述100个字符功能5描述100个字符功能5描述100个字符功能5描述100个字符功能5描述100个字符功能5描述100个字符

功能5上新100个字符功能5上新100个字符功能5上新100个字符功能5上新100个字符功能5上新100个字符功能5上新100个字符功能5上新100个字符功能5上新100个字符功能5上新100个字符功能5上新100个字符

功能4上新

文章&问答评论现已支持表情

全新交互，全新视觉，新增快捷键、悬浮工具栏、高亮块等功能并同时优化现有功能，全面提升创作效率和体验

社区富文本编辑器全新改版！诚邀体验～ 

精选全网热门MCP server，让你的AI更好用 🚀

💥开发者 MCP广场重磅上线！

涵盖代码开发、场景应用、自动测试全流程，助你从零构建专属AI助手

一站式MCP教程库，解锁AI应用新玩法

聚焦“写作效率、视觉美观与运行性能”三方面进行全面升级，为您提供更高效、稳定的创作环境

社区富文本&Markdown编辑器全新改版上线，欢迎大家体验!

诚挚邀请您参与本次调研，分享您的真实使用感受与建议。您的反馈至关重要，感谢您的支持与参与！

社区新版编辑器体验调研

原谅我愚蠢的问题。我想知道postgreSQL数据库集群(1个服务器、N个数据库、N个端口)与一个承载多个数据库的服务器(1个服务器、N个数据库、1个端口)之间的区别是什么？我读过集群这里，也读过这里和这。我只是不明白。对我来说更奇怪的是(因为我缺乏知识)，在OpDash上它说集群可以同时运行不同版本的postgres。:(在现实世界中有数据库聚类使用的示例吗？假设我想对主从复制进行高可用性，是否

问postgresql数据库集群与具有多个数据库的一台服务器
EN

回答 1

Database Administration用户

社区

活动

圈层

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问postgresql数据库集群与具有多个数据库的一台服务器EN