mirror of
https://github.com/element-hq/synapse.git
synced 2024-11-22 17:46:08 +03:00
366 lines
32 KiB
HTML
366 lines
32 KiB
HTML
<!DOCTYPE HTML>
|
||
<html lang="en" class="sidebar-visible no-js light">
|
||
<head>
|
||
<!-- Book generated using mdBook -->
|
||
<meta charset="UTF-8">
|
||
<title>Database Schemas - Synapse</title>
|
||
<!-- Custom HTML head -->
|
||
<meta content="text/html; charset=utf-8" http-equiv="Content-Type">
|
||
<meta name="description" content="">
|
||
<meta name="viewport" content="width=device-width, initial-scale=1">
|
||
<meta name="theme-color" content="#ffffff" />
|
||
|
||
<link rel="icon" href="../favicon.svg">
|
||
<link rel="shortcut icon" href="../favicon.png">
|
||
<link rel="stylesheet" href="../css/variables.css">
|
||
<link rel="stylesheet" href="../css/general.css">
|
||
<link rel="stylesheet" href="../css/chrome.css">
|
||
<link rel="stylesheet" href="../css/print.css" media="print">
|
||
<!-- Fonts -->
|
||
<link rel="stylesheet" href="../FontAwesome/css/font-awesome.css">
|
||
<link rel="stylesheet" href="../fonts/fonts.css">
|
||
<!-- Highlight.js Stylesheets -->
|
||
<link rel="stylesheet" href="../highlight.css">
|
||
<link rel="stylesheet" href="../tomorrow-night.css">
|
||
<link rel="stylesheet" href="../ayu-highlight.css">
|
||
|
||
<!-- Custom theme stylesheets -->
|
||
<link rel="stylesheet" href="../docs/website_files/table-of-contents.css">
|
||
<link rel="stylesheet" href="../docs/website_files/remove-nav-buttons.css">
|
||
<link rel="stylesheet" href="../docs/website_files/indent-section-headers.css">
|
||
<link rel="stylesheet" href="../docs/website_files/version-picker.css">
|
||
</head>
|
||
<body>
|
||
<!-- Provide site root to javascript -->
|
||
<script type="text/javascript">
|
||
var path_to_root = "../";
|
||
var default_theme = window.matchMedia("(prefers-color-scheme: dark)").matches ? "navy" : "light";
|
||
</script>
|
||
|
||
<!-- Work around some values being stored in localStorage wrapped in quotes -->
|
||
<script type="text/javascript">
|
||
try {
|
||
var theme = localStorage.getItem('mdbook-theme');
|
||
var sidebar = localStorage.getItem('mdbook-sidebar');
|
||
if (theme.startsWith('"') && theme.endsWith('"')) {
|
||
localStorage.setItem('mdbook-theme', theme.slice(1, theme.length - 1));
|
||
}
|
||
if (sidebar.startsWith('"') && sidebar.endsWith('"')) {
|
||
localStorage.setItem('mdbook-sidebar', sidebar.slice(1, sidebar.length - 1));
|
||
}
|
||
} catch (e) { }
|
||
</script>
|
||
|
||
<!-- Set the theme before any content is loaded, prevents flash -->
|
||
<script type="text/javascript">
|
||
var theme;
|
||
try { theme = localStorage.getItem('mdbook-theme'); } catch(e) { }
|
||
if (theme === null || theme === undefined) { theme = default_theme; }
|
||
var html = document.querySelector('html');
|
||
html.classList.remove('no-js')
|
||
html.classList.remove('light')
|
||
html.classList.add(theme);
|
||
html.classList.add('js');
|
||
</script>
|
||
|
||
<!-- Hide / unhide sidebar before it is displayed -->
|
||
<script type="text/javascript">
|
||
var html = document.querySelector('html');
|
||
var sidebar = 'hidden';
|
||
if (document.body.clientWidth >= 1080) {
|
||
try { sidebar = localStorage.getItem('mdbook-sidebar'); } catch(e) { }
|
||
sidebar = sidebar || 'visible';
|
||
}
|
||
html.classList.remove('sidebar-visible');
|
||
html.classList.add("sidebar-" + sidebar);
|
||
</script>
|
||
|
||
<nav id="sidebar" class="sidebar" aria-label="Table of contents">
|
||
<div class="sidebar-scrollbox">
|
||
<ol class="chapter"><li class="chapter-item expanded affix "><li class="part-title">Introduction</li><li class="chapter-item expanded "><a href="../welcome_and_overview.html">Welcome and Overview</a></li><li class="chapter-item expanded affix "><li class="part-title">Setup</li><li class="chapter-item expanded "><a href="../setup/installation.html">Installation</a></li><li class="chapter-item expanded "><a href="../postgres.html">Using Postgres</a></li><li class="chapter-item expanded "><a href="../reverse_proxy.html">Configuring a Reverse Proxy</a></li><li class="chapter-item expanded "><a href="../setup/forward_proxy.html">Configuring a Forward/Outbound Proxy</a></li><li class="chapter-item expanded "><a href="../turn-howto.html">Configuring a Turn Server</a></li><li class="chapter-item expanded "><a href="../delegate.html">Delegation</a></li><li class="chapter-item expanded affix "><li class="part-title">Upgrading</li><li class="chapter-item expanded "><a href="../upgrade.html">Upgrading between Synapse Versions</a></li><li class="chapter-item expanded affix "><li class="part-title">Usage</li><li class="chapter-item expanded "><a href="../federate.html">Federation</a></li><li class="chapter-item expanded "><a href="../usage/configuration/index.html">Configuration</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../usage/configuration/config_documentation.html">Configuration Manual</a></li><li class="chapter-item expanded "><a href="../usage/configuration/homeserver_sample_config.html">Homeserver Sample Config File</a></li><li class="chapter-item expanded "><a href="../usage/configuration/logging_sample_config.html">Logging Sample Config File</a></li><li class="chapter-item expanded "><a href="../structured_logging.html">Structured Logging</a></li><li class="chapter-item expanded "><a href="../templates.html">Templates</a></li><li class="chapter-item expanded "><a href="../usage/configuration/user_authentication/index.html">User Authentication</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../usage/configuration/user_authentication/single_sign_on/index.html">Single-Sign On</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../openid.html">OpenID Connect</a></li><li class="chapter-item expanded "><a href="../usage/configuration/user_authentication/single_sign_on/saml.html">SAML</a></li><li class="chapter-item expanded "><a href="../usage/configuration/user_authentication/single_sign_on/cas.html">CAS</a></li><li class="chapter-item expanded "><a href="../sso_mapping_providers.html">SSO Mapping Providers</a></li></ol></li><li class="chapter-item expanded "><a href="../password_auth_providers.html">Password Auth Providers</a></li><li class="chapter-item expanded "><a href="../jwt.html">JSON Web Tokens</a></li><li class="chapter-item expanded "><a href="../usage/configuration/user_authentication/refresh_tokens.html">Refresh Tokens</a></li></ol></li><li class="chapter-item expanded "><a href="../CAPTCHA_SETUP.html">Registration Captcha</a></li><li class="chapter-item expanded "><a href="../application_services.html">Application Services</a></li><li class="chapter-item expanded "><a href="../server_notices.html">Server Notices</a></li><li class="chapter-item expanded "><a href="../consent_tracking.html">Consent Tracking</a></li><li class="chapter-item expanded "><a href="../development/url_previews.html">URL Previews</a></li><li class="chapter-item expanded "><a href="../user_directory.html">User Directory</a></li><li class="chapter-item expanded "><a href="../message_retention_policies.html">Message Retention Policies</a></li><li class="chapter-item expanded "><a href="../modules/index.html">Pluggable Modules</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../modules/writing_a_module.html">Writing a module</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../modules/spam_checker_callbacks.html">Spam checker callbacks</a></li><li class="chapter-item expanded "><a href="../modules/third_party_rules_callbacks.html">Third-party rules callbacks</a></li><li class="chapter-item expanded "><a href="../modules/presence_router_callbacks.html">Presence router callbacks</a></li><li class="chapter-item expanded "><a href="../modules/account_validity_callbacks.html">Account validity callbacks</a></li><li class="chapter-item expanded "><a href="../modules/password_auth_provider_callbacks.html">Password auth provider callbacks</a></li><li class="chapter-item expanded "><a href="../modules/background_update_controller_callbacks.html">Background update controller callbacks</a></li><li class="chapter-item expanded "><a href="../modules/account_data_callbacks.html">Account data callbacks</a></li><li class="chapter-item expanded "><a href="../modules/porting_legacy_module.html">Porting a legacy module to the new interface</a></li></ol></li></ol></li><li class="chapter-item expanded "><a href="../workers.html">Workers</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../synctl_workers.html">Using synctl with Workers</a></li><li class="chapter-item expanded "><a href="../systemd-with-workers/index.html">Systemd</a></li></ol></li></ol></li><li class="chapter-item expanded "><a href="../usage/administration/index.html">Administration</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../usage/administration/admin_api/index.html">Admin API</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../admin_api/account_validity.html">Account Validity</a></li><li class="chapter-item expanded "><a href="../usage/administration/admin_api/background_updates.html">Background Updates</a></li><li class="chapter-item expanded "><a href="../admin_api/event_reports.html">Event Reports</a></li><li class="chapter-item expanded "><a href="../admin_api/media_admin_api.html">Media</a></li><li class="chapter-item expanded "><a href="../admin_api/purge_history_api.html">Purge History</a></li><li class="chapter-item expanded "><a href="../admin_api/register_api.html">Register Users</a></li><li class="chapter-item expanded "><a href="../usage/administration/admin_api/registration_tokens.html">Registration Tokens</a></li><li class="chapter-item expanded "><a href="../admin_api/room_membership.html">Manipulate Room Membership</a></li><li class="chapter-item expanded "><a href="../admin_api/rooms.html">Rooms</a></li><li class="chapter-item expanded "><a href="../admin_api/server_notices.html">Server Notices</a></li><li class="chapter-item expanded "><a href="../admin_api/statistics.html">Statistics</a></li><li class="chapter-item expanded "><a href="../admin_api/user_admin_api.html">Users</a></li><li class="chapter-item expanded "><a href="../admin_api/version_api.html">Server Version</a></li><li class="chapter-item expanded "><a href="../usage/administration/admin_api/federation.html">Federation</a></li></ol></li><li class="chapter-item expanded "><a href="../manhole.html">Manhole</a></li><li class="chapter-item expanded "><a href="../metrics-howto.html">Monitoring</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../usage/administration/monitoring/reporting_homeserver_usage_statistics.html">Reporting Homeserver Usage Statistics</a></li></ol></li><li class="chapter-item expanded "><a href="../usage/administration/understanding_synapse_through_grafana_graphs.html">Understanding Synapse Through Grafana Graphs</a></li><li class="chapter-item expanded "><a href="../usage/administration/useful_sql_for_admins.html">Useful SQL for Admins</a></li><li class="chapter-item expanded "><a href="../usage/administration/database_maintenance_tools.html">Database Maintenance Tools</a></li><li class="chapter-item expanded "><a href="../usage/administration/state_groups.html">State Groups</a></li><li class="chapter-item expanded "><a href="../usage/administration/request_log.html">Request log format</a></li><li class="chapter-item expanded "><a href="../usage/administration/admin_faq.html">Admin FAQ</a></li><li class="chapter-item expanded "><div>Scripts</div></li></ol></li><li class="chapter-item expanded "><li class="part-title">Development</li><li class="chapter-item expanded "><a href="../development/contributing_guide.html">Contributing Guide</a></li><li class="chapter-item expanded "><a href="../code_style.html">Code Style</a></li><li class="chapter-item expanded "><a href="../development/reviews.html">Reviewing Code</a></li><li class="chapter-item expanded "><a href="../development/releases.html">Release Cycle</a></li><li class="chapter-item expanded "><a href="../development/git.html">Git Usage</a></li><li class="chapter-item expanded "><div>Testing</div></li><li><ol class="section"><li class="chapter-item expanded "><a href="../development/demo.html">Demo scripts</a></li></ol></li><li class="chapter-item expanded "><a href="../opentracing.html">OpenTracing</a></li><li class="chapter-item expanded "><a href="../development/database_schema.html" class="active">Database Schemas</a></li><li class="chapter-item expanded "><a href="../development/experimental_features.html">Experimental features</a></li><li class="chapter-item expanded "><a href="../development/dependencies.html">Dependency management</a></li><li class="chapter-item expanded "><div>Synapse Architecture</div></li><li><ol class="section"><li class="chapter-item expanded "><a href="../development/synapse_architecture/cancellation.html">Cancellation</a></li><li class="chapter-item expanded "><a href="../log_contexts.html">Log Contexts</a></li><li class="chapter-item expanded "><a href="../replication.html">Replication</a></li><li class="chapter-item expanded "><a href="../tcp_replication.html">TCP Replication</a></li></ol></li><li class="chapter-item expanded "><a href="../development/internal_documentation/index.html">Internal Documentation</a></li><li><ol class="section"><li class="chapter-item expanded "><div>Single Sign-On</div></li><li><ol class="section"><li class="chapter-item expanded "><a href="../development/saml.html">SAML</a></li><li class="chapter-item expanded "><a href="../development/cas.html">CAS</a></li></ol></li><li class="chapter-item expanded "><a href="../development/room-dag-concepts.html">Room DAG concepts</a></li><li class="chapter-item expanded "><div>State Resolution</div></li><li><ol class="section"><li class="chapter-item expanded "><a href="../auth_chain_difference_algorithm.html">The Auth Chain Difference Algorithm</a></li></ol></li><li class="chapter-item expanded "><a href="../media_repository.html">Media Repository</a></li><li class="chapter-item expanded "><a href="../room_and_user_statistics.html">Room and User Statistics</a></li></ol></li><li class="chapter-item expanded "><div>Scripts</div></li><li class="chapter-item expanded affix "><li class="part-title">Other</li><li class="chapter-item expanded "><a href="../deprecation_policy.html">Dependency Deprecation Policy</a></li><li class="chapter-item expanded "><a href="../other/running_synapse_on_single_board_computers.html">Running Synapse on a Single-Board Computer</a></li></ol>
|
||
</div>
|
||
<div id="sidebar-resize-handle" class="sidebar-resize-handle"></div>
|
||
</nav>
|
||
|
||
<div id="page-wrapper" class="page-wrapper">
|
||
|
||
<div class="page">
|
||
<div id="menu-bar-hover-placeholder"></div>
|
||
<div id="menu-bar" class="menu-bar sticky bordered">
|
||
<div class="left-buttons">
|
||
<button id="sidebar-toggle" class="icon-button" type="button" title="Toggle Table of Contents" aria-label="Toggle Table of Contents" aria-controls="sidebar">
|
||
<i class="fa fa-bars"></i>
|
||
</button>
|
||
<button id="theme-toggle" class="icon-button" type="button" title="Change theme" aria-label="Change theme" aria-haspopup="true" aria-expanded="false" aria-controls="theme-list">
|
||
<i class="fa fa-paint-brush"></i>
|
||
</button>
|
||
<ul id="theme-list" class="theme-popup" aria-label="Themes" role="menu">
|
||
<li role="none"><button role="menuitem" class="theme" id="light">Light (default)</button></li>
|
||
<li role="none"><button role="menuitem" class="theme" id="rust">Rust</button></li>
|
||
<li role="none"><button role="menuitem" class="theme" id="coal">Coal</button></li>
|
||
<li role="none"><button role="menuitem" class="theme" id="navy">Navy</button></li>
|
||
<li role="none"><button role="menuitem" class="theme" id="ayu">Ayu</button></li>
|
||
</ul>
|
||
<button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
|
||
<i class="fa fa-search"></i>
|
||
</button>
|
||
<div class="version-picker">
|
||
<div class="dropdown">
|
||
<div class="select">
|
||
<span></span>
|
||
<i class="fa fa-chevron-down"></i>
|
||
</div>
|
||
<input type="hidden" name="version">
|
||
<ul class="dropdown-menu">
|
||
<!-- Versions will be added dynamically in version-picker.js -->
|
||
</ul>
|
||
</div>
|
||
</div>
|
||
</div>
|
||
|
||
<h1 class="menu-title">Synapse</h1>
|
||
|
||
<div class="right-buttons">
|
||
<a href="../print.html" title="Print this book" aria-label="Print this book">
|
||
<i id="print-button" class="fa fa-print"></i>
|
||
</a>
|
||
<a href="https://github.com/matrix-org/synapse" title="Git repository" aria-label="Git repository">
|
||
<i id="git-repository-button" class="fa fa-github"></i>
|
||
</a>
|
||
<a href="https://github.com/matrix-org/synapse/edit/develop/docs/development/database_schema.md" title="Suggest an edit" aria-label="Suggest an edit">
|
||
<i id="git-edit-button" class="fa fa-edit"></i>
|
||
</a>
|
||
</div>
|
||
</div>
|
||
|
||
<div id="search-wrapper" class="hidden">
|
||
<form id="searchbar-outer" class="searchbar-outer">
|
||
<input type="search" id="searchbar" name="searchbar" placeholder="Search this book ..." aria-controls="searchresults-outer" aria-describedby="searchresults-header">
|
||
</form>
|
||
<div id="searchresults-outer" class="searchresults-outer hidden">
|
||
<div id="searchresults-header" class="searchresults-header"></div>
|
||
<ul id="searchresults">
|
||
</ul>
|
||
</div>
|
||
</div>
|
||
<!-- Apply ARIA attributes after the sidebar and the sidebar toggle button are added to the DOM -->
|
||
<script type="text/javascript">
|
||
document.getElementById('sidebar-toggle').setAttribute('aria-expanded', sidebar === 'visible');
|
||
document.getElementById('sidebar').setAttribute('aria-hidden', sidebar !== 'visible');
|
||
Array.from(document.querySelectorAll('#sidebar a')).forEach(function(link) {
|
||
link.setAttribute('tabIndex', sidebar === 'visible' ? 0 : -1);
|
||
});
|
||
</script>
|
||
|
||
<div id="content" class="content">
|
||
<main>
|
||
<!-- Page table of contents -->
|
||
<div class="sidetoc">
|
||
<nav class="pagetoc"></nav>
|
||
</div>
|
||
|
||
<h1 id="synapse-database-schema-files"><a class="header" href="#synapse-database-schema-files">Synapse database schema files</a></h1>
|
||
<p>Synapse's database schema is stored in the <code>synapse.storage.schema</code> module.</p>
|
||
<h2 id="logical-databases"><a class="header" href="#logical-databases">Logical databases</a></h2>
|
||
<p>Synapse supports splitting its datastore across multiple physical databases (which can
|
||
be useful for large installations), and the schema files are therefore split according
|
||
to the logical database they apply to.</p>
|
||
<p>At the time of writing, the following "logical" databases are supported:</p>
|
||
<ul>
|
||
<li><code>state</code> - used to store Matrix room state (more specifically, <code>state_groups</code>,
|
||
their relationships and contents).</li>
|
||
<li><code>main</code> - stores everything else.</li>
|
||
</ul>
|
||
<p>Additionally, the <code>common</code> directory contains schema files for tables which must be
|
||
present on <em>all</em> physical databases.</p>
|
||
<h2 id="synapse-schema-versions"><a class="header" href="#synapse-schema-versions">Synapse schema versions</a></h2>
|
||
<p>Synapse manages its database schema via "schema versions". These are mainly used to
|
||
help avoid confusion if the Synapse codebase is rolled back after the database is
|
||
updated. They work as follows:</p>
|
||
<ul>
|
||
<li>
|
||
<p>The Synapse codebase defines a constant <code>synapse.storage.schema.SCHEMA_VERSION</code>
|
||
which represents the expectations made about the database by that version. For
|
||
example, as of Synapse v1.36, this is <code>59</code>.</p>
|
||
</li>
|
||
<li>
|
||
<p>The database stores a "compatibility version" in
|
||
<code>schema_compat_version.compat_version</code> which defines the <code>SCHEMA_VERSION</code> of the
|
||
oldest version of Synapse which will work with the database. On startup, if
|
||
<code>compat_version</code> is found to be newer than <code>SCHEMA_VERSION</code>, Synapse will refuse to
|
||
start.</p>
|
||
<p>Synapse automatically updates this field from
|
||
<code>synapse.storage.schema.SCHEMA_COMPAT_VERSION</code>.</p>
|
||
</li>
|
||
<li>
|
||
<p>Whenever a backwards-incompatible change is made to the database format (normally
|
||
via a <code>delta</code> file), <code>synapse.storage.schema.SCHEMA_COMPAT_VERSION</code> is also updated
|
||
so that administrators can not accidentally roll back to a too-old version of Synapse.</p>
|
||
</li>
|
||
</ul>
|
||
<p>Generally, the goal is to maintain compatibility with at least one or two previous
|
||
releases of Synapse, so any substantial change tends to require multiple releases and a
|
||
bit of forward-planning to get right.</p>
|
||
<p>As a worked example: we want to remove the <code>room_stats_historical</code> table. Here is how it
|
||
might pan out.</p>
|
||
<ol>
|
||
<li>
|
||
<p>Replace any code that <em>reads</em> from <code>room_stats_historical</code> with alternative
|
||
implementations, but keep writing to it in case of rollback to an earlier version.
|
||
Also, increase <code>synapse.storage.schema.SCHEMA_VERSION</code>. In this
|
||
instance, there is no existing code which reads from <code>room_stats_historical</code>, so
|
||
our starting point is:</p>
|
||
<p>v1.36.0: <code>SCHEMA_VERSION=59</code>, <code>SCHEMA_COMPAT_VERSION=59</code></p>
|
||
</li>
|
||
<li>
|
||
<p>Next (say in Synapse v1.37.0): remove the code that <em>writes</em> to
|
||
<code>room_stats_historical</code>, but don’t yet remove the table in case of rollback to
|
||
v1.36.0. Again, we increase <code>synapse.storage.schema.SCHEMA_VERSION</code>, but
|
||
because we have not broken compatibility with v1.36, we do not yet update
|
||
<code>SCHEMA_COMPAT_VERSION</code>. We now have:</p>
|
||
<p>v1.37.0: <code>SCHEMA_VERSION=60</code>, <code>SCHEMA_COMPAT_VERSION=59</code>.</p>
|
||
</li>
|
||
<li>
|
||
<p>Later (say in Synapse v1.38.0): we can remove the table altogether. This will
|
||
break compatibility with v1.36.0, so we must update <code>SCHEMA_COMPAT_VERSION</code> accordingly.
|
||
There is no need to update <code>synapse.storage.schema.SCHEMA_VERSION</code>, since there is no
|
||
change to the Synapse codebase here. So we end up with:</p>
|
||
<p>v1.38.0: <code>SCHEMA_VERSION=60</code>, <code>SCHEMA_COMPAT_VERSION=60</code>.</p>
|
||
</li>
|
||
</ol>
|
||
<p>If in doubt about whether to update <code>SCHEMA_VERSION</code> or not, it is generally best to
|
||
lean towards doing so.</p>
|
||
<h2 id="full-schema-dumps"><a class="header" href="#full-schema-dumps">Full schema dumps</a></h2>
|
||
<p>In the <code>full_schemas</code> directories, only the most recently-numbered snapshot is used
|
||
(<code>54</code> at the time of writing). Older snapshots (eg, <code>16</code>) are present for historical
|
||
reference only.</p>
|
||
<h3 id="building-full-schema-dumps"><a class="header" href="#building-full-schema-dumps">Building full schema dumps</a></h3>
|
||
<p>If you want to recreate these schemas, they need to be made from a database that
|
||
has had all background updates run.</p>
|
||
<p>To do so, use <code>scripts-dev/make_full_schema.sh</code>. This will produce new
|
||
<code>full.sql.postgres</code> and <code>full.sql.sqlite</code> files.</p>
|
||
<p>Ensure postgres is installed, then run:</p>
|
||
<pre><code class="language-sh">./scripts-dev/make_full_schema.sh -p postgres_username -o output_dir/
|
||
</code></pre>
|
||
<p>NB at the time of writing, this script predates the split into separate <code>state</code>/<code>main</code>
|
||
databases so will require updates to handle that correctly.</p>
|
||
<h2 id="delta-files"><a class="header" href="#delta-files">Delta files</a></h2>
|
||
<p>Delta files define the steps required to upgrade the database from an earlier version.
|
||
They can be written as either a file containing a series of SQL statements, or a Python
|
||
module.</p>
|
||
<p>Synapse remembers which delta files it has applied to a database (they are stored in the
|
||
<code>applied_schema_deltas</code> table) and will not re-apply them (even if a given file is
|
||
subsequently updated).</p>
|
||
<p>Delta files should be placed in a directory named <code>synapse/storage/schema/<database>/delta/<version>/</code>.
|
||
They are applied in alphanumeric order, so by convention the first two characters
|
||
of the filename should be an integer such as <code>01</code>, to put the file in the right order.</p>
|
||
<h3 id="sql-delta-files"><a class="header" href="#sql-delta-files">SQL delta files</a></h3>
|
||
<p>These should be named <code>*.sql</code>, or — for changes which should only be applied for a
|
||
given database engine — <code>*.sql.posgres</code> or <code>*.sql.sqlite</code>. For example, a delta which
|
||
adds a new column to the <code>foo</code> table might be called <code>01add_bar_to_foo.sql</code>.</p>
|
||
<p>Note that our SQL parser is a bit simple - it understands comments (<code>--</code> and <code>/*...*/</code>),
|
||
but complex statements which require a <code>;</code> in the middle of them (such as <code>CREATE TRIGGER</code>) are beyond it and you'll have to use a Python delta file.</p>
|
||
<h3 id="python-delta-files"><a class="header" href="#python-delta-files">Python delta files</a></h3>
|
||
<p>For more flexibility, a delta file can take the form of a python module. These should
|
||
be named <code>*.py</code>. Note that database-engine-specific modules are not supported here –
|
||
instead you can write <code>if isinstance(database_engine, PostgresEngine)</code> or similar.</p>
|
||
<p>A Python delta module should define either or both of the following functions:</p>
|
||
<pre><code class="language-python">import synapse.config.homeserver
|
||
import synapse.storage.engines
|
||
import synapse.storage.types
|
||
|
||
|
||
def run_create(
|
||
cur: synapse.storage.types.Cursor,
|
||
database_engine: synapse.storage.engines.BaseDatabaseEngine,
|
||
) -> None:
|
||
"""Called whenever an existing or new database is to be upgraded"""
|
||
...
|
||
|
||
def run_upgrade(
|
||
cur: synapse.storage.types.Cursor,
|
||
database_engine: synapse.storage.engines.BaseDatabaseEngine,
|
||
config: synapse.config.homeserver.HomeServerConfig,
|
||
) -> None:
|
||
"""Called whenever an existing database is to be upgraded."""
|
||
...
|
||
</code></pre>
|
||
<h2 id="boolean-columns"><a class="header" href="#boolean-columns">Boolean columns</a></h2>
|
||
<p>Boolean columns require special treatment, since SQLite treats booleans the
|
||
same as integers.</p>
|
||
<p>There are three separate aspects to this:</p>
|
||
<ul>
|
||
<li>
|
||
<p>Any new boolean column must be added to the <code>BOOLEAN_COLUMNS</code> list in
|
||
<code>synapse/_scripts/synapse_port_db.py</code>. This tells the port script to cast
|
||
the integer value from SQLite to a boolean before writing the value to the
|
||
postgres database.</p>
|
||
</li>
|
||
<li>
|
||
<p>Before SQLite 3.23, <code>TRUE</code> and <code>FALSE</code> were not recognised as constants by
|
||
SQLite, and the <code>IS [NOT] TRUE</code>/<code>IS [NOT] FALSE</code> operators were not
|
||
supported. This makes it necessary to avoid using <code>TRUE</code> and <code>FALSE</code>
|
||
constants in SQL commands.</p>
|
||
<p>For example, to insert a <code>TRUE</code> value into the database, write:</p>
|
||
<pre><code class="language-python">txn.execute("INSERT INTO tbl(col) VALUES (?)", (True, ))
|
||
</code></pre>
|
||
</li>
|
||
<li>
|
||
<p>Default values for new boolean columns present a particular
|
||
difficulty. Generally it is best to create separate schema files for
|
||
Postgres and SQLite. For example:</p>
|
||
<pre><code class="language-sql"># in 00delta.sql.postgres:
|
||
ALTER TABLE tbl ADD COLUMN col BOOLEAN DEFAULT FALSE;
|
||
</code></pre>
|
||
<pre><code class="language-sql"># in 00delta.sql.sqlite:
|
||
ALTER TABLE tbl ADD COLUMN col BOOLEAN DEFAULT 0;
|
||
</code></pre>
|
||
<p>Note that there is a particularly insidious failure mode here: the Postgres
|
||
flavour will be accepted by SQLite 3.22, but will give a column whose
|
||
default value is the <strong>string</strong> <code>"FALSE"</code> - which, when cast back to a boolean
|
||
in Python, evaluates to <code>True</code>.</p>
|
||
</li>
|
||
</ul>
|
||
|
||
</main>
|
||
|
||
<nav class="nav-wrapper" aria-label="Page navigation">
|
||
<!-- Mobile navigation buttons -->
|
||
<a rel="prev" href="../opentracing.html" class="mobile-nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
|
||
<i class="fa fa-angle-left"></i>
|
||
</a>
|
||
<a rel="next" href="../development/experimental_features.html" class="mobile-nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
|
||
<i class="fa fa-angle-right"></i>
|
||
</a>
|
||
<div style="clear: both"></div>
|
||
</nav>
|
||
</div>
|
||
</div>
|
||
|
||
<nav class="nav-wide-wrapper" aria-label="Page navigation">
|
||
<a rel="prev" href="../opentracing.html" class="nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
|
||
<i class="fa fa-angle-left"></i>
|
||
</a>
|
||
<a rel="next" href="../development/experimental_features.html" class="nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
|
||
<i class="fa fa-angle-right"></i>
|
||
</a>
|
||
</nav>
|
||
|
||
</div>
|
||
|
||
<script type="text/javascript">
|
||
window.playground_copyable = true;
|
||
</script>
|
||
<script src="../elasticlunr.min.js" type="text/javascript" charset="utf-8"></script>
|
||
<script src="../mark.min.js" type="text/javascript" charset="utf-8"></script>
|
||
<script src="../searcher.js" type="text/javascript" charset="utf-8"></script>
|
||
<script src="../clipboard.min.js" type="text/javascript" charset="utf-8"></script>
|
||
<script src="../highlight.js" type="text/javascript" charset="utf-8"></script>
|
||
<script src="../book.js" type="text/javascript" charset="utf-8"></script>
|
||
|
||
<!-- Custom JS scripts -->
|
||
<script type="text/javascript" src="../docs/website_files/table-of-contents.js"></script>
|
||
<script type="text/javascript" src="../docs/website_files/version-picker.js"></script>
|
||
<script type="text/javascript" src="../docs/website_files/version.js"></script>
|
||
</body>
|
||
</html>
|