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| author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-04 12:17:33 +0000 |
|---|---|---|
| committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-04 12:17:33 +0000 |
| commit | 5e45211a64149b3c659b90ff2de6fa982a5a93ed (patch) | |
| tree | 739caf8c461053357daa9f162bef34516c7bf452 /doc/src/sgml/html/manage-ag-overview.html | |
| parent | Initial commit. (diff) | |
| download | postgresql-15-5e45211a64149b3c659b90ff2de6fa982a5a93ed.tar.xz postgresql-15-5e45211a64149b3c659b90ff2de6fa982a5a93ed.zip | |
Adding upstream version 15.5.upstream/15.5
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'doc/src/sgml/html/manage-ag-overview.html')
| -rw-r--r-- | doc/src/sgml/html/manage-ag-overview.html | 59 |
1 files changed, 59 insertions, 0 deletions
diff --git a/doc/src/sgml/html/manage-ag-overview.html b/doc/src/sgml/html/manage-ag-overview.html new file mode 100644 index 0000000..4f07288 --- /dev/null +++ b/doc/src/sgml/html/manage-ag-overview.html @@ -0,0 +1,59 @@ +<?xml version="1.0" encoding="UTF-8" standalone="no"?> +<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>23.1. Overview</title><link rel="stylesheet" type="text/css" href="stylesheet.css" /><link rev="made" href="pgsql-docs@lists.postgresql.org" /><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><link rel="prev" href="managing-databases.html" title="Chapter 23. Managing Databases" /><link rel="next" href="manage-ag-createdb.html" title="23.2. Creating a Database" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">23.1. Overview</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="managing-databases.html" title="Chapter 23. Managing Databases">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="managing-databases.html" title="Chapter 23. Managing Databases">Up</a></td><th width="60%" align="center">Chapter 23. Managing Databases</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 15.5 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="manage-ag-createdb.html" title="23.2. Creating a Database">Next</a></td></tr></table><hr /></div><div class="sect1" id="MANAGE-AG-OVERVIEW"><div class="titlepage"><div><div><h2 class="title" style="clear: both">23.1. Overview</h2></div></div></div><a id="id-1.6.10.4.2" class="indexterm"></a><p> + A small number of objects, like role, database, and tablespace + names, are defined at the cluster level and stored in the + <code class="literal">pg_global</code> tablespace. Inside the cluster are + multiple databases, which are isolated from each other but can access + cluster-level objects. Inside each database are multiple schemas, + which contain objects like tables and functions. So the full hierarchy + is: cluster, database, schema, table (or some other kind of object, + such as a function). + </p><p> + When connecting to the database server, a client must specify the + database name in its connection request. + It is not possible to access more than one database per + connection. However, clients can open multiple connections to + the same database, or different databases. + Database-level security has two components: access control + (see <a class="xref" href="auth-pg-hba-conf.html" title="21.1. The pg_hba.conf File">Section 21.1</a>), managed at the + connection level, and authorization control + (see <a class="xref" href="ddl-priv.html" title="5.7. Privileges">Section 5.7</a>), managed via the grant system. + Foreign data wrappers (see <a class="xref" href="postgres-fdw.html" title="F.38. postgres_fdw">postgres_fdw</a>) + allow for objects within one database to act as proxies for objects in + other database or clusters. + The older dblink module (see <a class="xref" href="dblink.html" title="F.12. dblink">dblink</a>) provides a similar capability. + By default, all users can connect to all databases using all connection methods. + </p><p> + If one <span class="productname">PostgreSQL</span> server cluster is planned to contain + unrelated projects or users that should be, for the most part, unaware + of each other, it is recommended to put them into separate databases and + adjust authorizations and access controls accordingly. + If the projects or users are interrelated, and thus should be able to use + each other's resources, they should be put in the same database but probably + into separate schemas; this provides a modular structure with namespace + isolation and authorization control. + More information about managing schemas is in <a class="xref" href="ddl-schemas.html" title="5.9. Schemas">Section 5.9</a>. + </p><p> + While multiple databases can be created within a single cluster, it is advised + to consider carefully whether the benefits outweigh the risks and limitations. + In particular, the impact that having a shared WAL (see <a class="xref" href="wal.html" title="Chapter 30. Reliability and the Write-Ahead Log">Chapter 30</a>) + has on backup and recovery options. While individual databases in the cluster + are isolated when considered from the user's perspective, they are closely bound + from the database administrator's point-of-view. + </p><p> + Databases are created with the <code class="command">CREATE DATABASE</code> command + (see <a class="xref" href="manage-ag-createdb.html" title="23.2. Creating a Database">Section 23.2</a>) and destroyed with the + <code class="command">DROP DATABASE</code> command + (see <a class="xref" href="manage-ag-dropdb.html" title="23.5. Destroying a Database">Section 23.5</a>). + To determine the set of existing databases, examine the + <code class="structname">pg_database</code> system catalog, for example +</p><pre class="synopsis"> +SELECT datname FROM pg_database; +</pre><p> + The <a class="xref" href="app-psql.html" title="psql"><span class="refentrytitle"><span class="application">psql</span></span></a> program's <code class="literal">\l</code> meta-command + and <code class="option">-l</code> command-line option are also useful for listing the + existing databases. + </p><div class="note"><h3 class="title">Note</h3><p> + The <acronym class="acronym">SQL</acronym> standard calls databases <span class="quote">“<span class="quote">catalogs</span>”</span>, but there + is no difference in practice. + </p></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="managing-databases.html" title="Chapter 23. Managing Databases">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="managing-databases.html" title="Chapter 23. Managing Databases">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="manage-ag-createdb.html" title="23.2. Creating a Database">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Chapter 23. Managing Databases </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 15.5 Documentation">Home</a></td><td width="40%" align="right" valign="top"> 23.2. Creating a Database</td></tr></table></div></body></html>
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