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2021-09-21 16:05:07 +03:00
< 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 " > < a href = "../MSC1711_certificates_FAQ.html" > Upgrading from pre-Synapse 1.0< / 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/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 " > < div > Single-Sign On< / div > < / li > < li > < ol class = "section" > < li class = "chapter-item expanded " > < a href = "../openid.html" > OpenID Connect< / a > < / li > < li class = "chapter-item expanded " > < div > SAML< / div > < / li > < li class = "chapter-item expanded " > < div > CAS< / div > < / 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 > < / 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
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< 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’
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 > ./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 = "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 > scripts/synapse_port_db< / 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 >
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