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| author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-16 19:46:48 +0000 |
|---|---|---|
| committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-16 19:46:48 +0000 |
| commit | 311bcfc6b3acdd6fd152798c7f287ddf74fa2a98 (patch) | |
| tree | 0ec307299b1dada3701e42f4ca6eda57d708261e /doc/src/sgml/html/high-availability.html | |
| parent | Initial commit. (diff) | |
| download | postgresql-15-upstream.tar.xz postgresql-15-upstream.zip | |
Adding upstream version 15.4.upstream/15.4upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
| -rw-r--r-- | doc/src/sgml/html/high-availability.html | 57 |
1 files changed, 57 insertions, 0 deletions
diff --git a/doc/src/sgml/html/high-availability.html b/doc/src/sgml/html/high-availability.html new file mode 100644 index 0000000..bd7e749 --- /dev/null +++ b/doc/src/sgml/html/high-availability.html @@ -0,0 +1,57 @@ +<?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>Chapter 27. High Availability, Load Balancing, and Replication</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="continuous-archiving.html" title="26.3. Continuous Archiving and Point-in-Time Recovery (PITR)" /><link rel="next" href="different-replication-solutions.html" title="27.1. Comparison of Different Solutions" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">Chapter 27. High Availability, Load Balancing, and Replication</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="continuous-archiving.html" title="26.3. Continuous Archiving and Point-in-Time Recovery (PITR)">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="admin.html" title="Part III. Server Administration">Up</a></td><th width="60%" align="center">Part III. Server Administration</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 15.4 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="different-replication-solutions.html" title="27.1. Comparison of Different Solutions">Next</a></td></tr></table><hr /></div><div class="chapter" id="HIGH-AVAILABILITY"><div class="titlepage"><div><div><h2 class="title">Chapter 27. High Availability, Load Balancing, and Replication</h2></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="sect1"><a href="different-replication-solutions.html">27.1. Comparison of Different Solutions</a></span></dt><dt><span class="sect1"><a href="warm-standby.html">27.2. Log-Shipping Standby Servers</a></span></dt><dd><dl><dt><span class="sect2"><a href="warm-standby.html#STANDBY-PLANNING">27.2.1. Planning</a></span></dt><dt><span class="sect2"><a href="warm-standby.html#STANDBY-SERVER-OPERATION">27.2.2. Standby Server Operation</a></span></dt><dt><span class="sect2"><a href="warm-standby.html#PREPARING-PRIMARY-FOR-STANDBY">27.2.3. Preparing the Primary for Standby Servers</a></span></dt><dt><span class="sect2"><a href="warm-standby.html#STANDBY-SERVER-SETUP">27.2.4. Setting Up a Standby Server</a></span></dt><dt><span class="sect2"><a href="warm-standby.html#STREAMING-REPLICATION">27.2.5. Streaming Replication</a></span></dt><dt><span class="sect2"><a href="warm-standby.html#STREAMING-REPLICATION-SLOTS">27.2.6. Replication Slots</a></span></dt><dt><span class="sect2"><a href="warm-standby.html#CASCADING-REPLICATION">27.2.7. Cascading Replication</a></span></dt><dt><span class="sect2"><a href="warm-standby.html#SYNCHRONOUS-REPLICATION">27.2.8. Synchronous Replication</a></span></dt><dt><span class="sect2"><a href="warm-standby.html#CONTINUOUS-ARCHIVING-IN-STANDBY">27.2.9. Continuous Archiving in Standby</a></span></dt></dl></dd><dt><span class="sect1"><a href="warm-standby-failover.html">27.3. Failover</a></span></dt><dt><span class="sect1"><a href="hot-standby.html">27.4. Hot Standby</a></span></dt><dd><dl><dt><span class="sect2"><a href="hot-standby.html#HOT-STANDBY-USERS">27.4.1. User's Overview</a></span></dt><dt><span class="sect2"><a href="hot-standby.html#HOT-STANDBY-CONFLICT">27.4.2. Handling Query Conflicts</a></span></dt><dt><span class="sect2"><a href="hot-standby.html#HOT-STANDBY-ADMIN">27.4.3. Administrator's Overview</a></span></dt><dt><span class="sect2"><a href="hot-standby.html#HOT-STANDBY-PARAMETERS">27.4.4. Hot Standby Parameter Reference</a></span></dt><dt><span class="sect2"><a href="hot-standby.html#HOT-STANDBY-CAVEATS">27.4.5. Caveats</a></span></dt></dl></dd></dl></div><a id="id-1.6.14.2" class="indexterm"></a><a id="id-1.6.14.3" class="indexterm"></a><a id="id-1.6.14.4" class="indexterm"></a><a id="id-1.6.14.5" class="indexterm"></a><a id="id-1.6.14.6" class="indexterm"></a><a id="id-1.6.14.7" class="indexterm"></a><p> + Database servers can work together to allow a second server to + take over quickly if the primary server fails (high + availability), or to allow several computers to serve the same + data (load balancing). Ideally, database servers could work + together seamlessly. Web servers serving static web pages can + be combined quite easily by merely load-balancing web requests + to multiple machines. In fact, read-only database servers can + be combined relatively easily too. Unfortunately, most database + servers have a read/write mix of requests, and read/write servers + are much harder to combine. This is because though read-only + data needs to be placed on each server only once, a write to any + server has to be propagated to all servers so that future read + requests to those servers return consistent results. + </p><p> + This synchronization problem is the fundamental difficulty for + servers working together. Because there is no single solution + that eliminates the impact of the sync problem for all use cases, + there are multiple solutions. Each solution addresses this + problem in a different way, and minimizes its impact for a specific + workload. + </p><p> + Some solutions deal with synchronization by allowing only one + server to modify the data. Servers that can modify data are + called read/write, <em class="firstterm">master</em> or <em class="firstterm">primary</em> servers. + Servers that track changes in the primary are called <em class="firstterm">standby</em> + or <em class="firstterm">secondary</em> servers. A standby server that cannot be connected + to until it is promoted to a primary server is called a <em class="firstterm">warm + standby</em> server, and one that can accept connections and serves read-only + queries is called a <em class="firstterm">hot standby</em> server. + </p><p> + Some solutions are synchronous, + meaning that a data-modifying transaction is not considered + committed until all servers have committed the transaction. This + guarantees that a failover will not lose any data and that all + load-balanced servers will return consistent results no matter + which server is queried. In contrast, asynchronous solutions allow some + delay between the time of a commit and its propagation to the other servers, + opening the possibility that some transactions might be lost in + the switch to a backup server, and that load balanced servers + might return slightly stale results. Asynchronous communication + is used when synchronous would be too slow. + </p><p> + Solutions can also be categorized by their granularity. Some solutions + can deal only with an entire database server, while others allow control + at the per-table or per-database level. + </p><p> + Performance must be considered in any choice. There is usually a + trade-off between functionality and + performance. For example, a fully synchronous solution over a slow + network might cut performance by more than half, while an asynchronous + one might have a minimal performance impact. + </p><p> + The remainder of this section outlines various failover, replication, + and load balancing solutions. + </p></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="continuous-archiving.html" title="26.3. Continuous Archiving and Point-in-Time Recovery (PITR)">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="admin.html" title="Part III. Server Administration">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="different-replication-solutions.html" title="27.1. Comparison of Different Solutions">Next</a></td></tr><tr><td width="40%" align="left" valign="top">26.3. Continuous Archiving and Point-in-Time Recovery (PITR) </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 15.4 Documentation">Home</a></td><td width="40%" align="right" valign="top"> 27.1. Comparison of Different Solutions</td></tr></table></div></body></html>
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