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< 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" class = "active" > 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 > < ol class = "section" > < li class = "chapter-item expanded " > < a href = "setup/turn/coturn.html" > coturn TURN server< / a > < / li > < li class = "chapter-item expanded " > < a href = "setup/turn/eturnal.html" > eturnal TURN server< / a > < / li > < / ol > < / 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 = "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
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< h1 id = "using-postgres" > < a class = "header" href = "#using-postgres" > Using Postgres< / a > < / h1 >
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< p > The minimum supported version of PostgreSQL is determined by the < a href = "deprecation_policy.html" > Dependency
Deprecation Policy< / a > .< / p >
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< h2 id = "install-postgres-client-libraries" > < a class = "header" href = "#install-postgres-client-libraries" > Install postgres client libraries< / a > < / h2 >
< p > Synapse will require the python postgres client library in order to
connect to a postgres database.< / p >
< ul >
< li >
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< p > If you are using the < a href = "setup/installation.html#matrixorg-packages" > matrix.org debian/ubuntu
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packages< / a > , the necessary python
library will already be installed, but you will need to ensure the
low-level postgres library is installed, which you can do with
< code > apt install libpq5< / code > .< / p >
< / li >
< li >
< p > For other pre-built packages, please consult the documentation from
the relevant package.< / p >
< / li >
< li >
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< p > If you installed synapse < a href = "setup/installation.html#installing-as-a-python-module-from-pypi" > in a
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virtualenv< / a > , you can install
the library with:< / p >
< pre > < code > ~/synapse/env/bin/pip install " matrix-synapse[postgres]"
< / code > < / pre >
< p > (substituting the path to your virtualenv for < code > ~/synapse/env< / code > , if
you used a different path). You will require the postgres
development files. These are in the < code > libpq-dev< / code > package on
Debian-derived distributions.< / p >
< / li >
< / ul >
< h2 id = "set-up-database" > < a class = "header" href = "#set-up-database" > Set up database< / a > < / h2 >
< p > Assuming your PostgreSQL database user is called < code > postgres< / code > , first authenticate as the database user with:< / p >
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< pre > < code class = "language-sh" > su - postgres
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# Or, if your system uses sudo to get administrative rights
sudo -u postgres bash
< / code > < / pre >
< p > Then, create a postgres user and a database with:< / p >
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< pre > < code class = "language-sh" > # this will prompt for a password for the new user
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createuser --pwprompt synapse_user
createdb --encoding=UTF8 --locale=C --template=template0 --owner=synapse_user synapse
< / code > < / pre >
< p > The above will create a user called < code > synapse_user< / code > , and a database called
< code > synapse< / code > .< / p >
< p > Note that the PostgreSQL database < em > must< / em > have the correct encoding set
(as shown above), otherwise it will not be able to store UTF8 strings.< / p >
< p > You may need to enable password authentication so < code > synapse_user< / code > can
connect to the database. See
< a href = "https://www.postgresql.org/docs/current/auth-pg-hba-conf.html" > https://www.postgresql.org/docs/current/auth-pg-hba-conf.html< / a > .< / p >
< h2 id = "synapse-config" > < a class = "header" href = "#synapse-config" > Synapse config< / a > < / h2 >
< p > When you are ready to start using PostgreSQL, edit the < code > database< / code >
section in your config file to match the following lines:< / p >
< pre > < code class = "language-yaml" > database:
name: psycopg2
args:
user: < user>
password: < pass>
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dbname: < db>
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host: < host>
cp_min: 5
cp_max: 10
< / code > < / pre >
< p > All key, values in < code > args< / code > are passed to the < code > psycopg2.connect(..)< / code >
function, except keys beginning with < code > cp_< / code > , which are consumed by the
twisted adbapi connection pool. See the < a href = "https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-PARAMKEYWORDS" > libpq
documentation< / a >
for a list of options which can be passed.< / p >
< p > You should consider tuning the < code > args.keepalives_*< / code > options if there is any danger of
the connection between your homeserver and database dropping, otherwise Synapse
may block for an extended period while it waits for a response from the
database server. Example values might be:< / p >
< pre > < code class = "language-yaml" > database:
args:
# ... as above
# seconds of inactivity after which TCP should send a keepalive message to the server
keepalives_idle: 10
# the number of seconds after which a TCP keepalive message that is not
# acknowledged by the server should be retransmitted
keepalives_interval: 10
# the number of TCP keepalives that can be lost before the client's connection
# to the server is considered dead
keepalives_count: 3
< / code > < / pre >
< h2 id = "tuning-postgres" > < a class = "header" href = "#tuning-postgres" > Tuning Postgres< / a > < / h2 >
< p > The default settings should be fine for most deployments. For larger
scale deployments tuning some of the settings is recommended, details of
which can be found at
< a href = "https://wiki.postgresql.org/wiki/Tuning_Your_PostgreSQL_Server" > https://wiki.postgresql.org/wiki/Tuning_Your_PostgreSQL_Server< / a > .< / p >
< p > In particular, we've found tuning the following values helpful for
performance:< / p >
< ul >
< li > < code > shared_buffers< / code > < / li >
< li > < code > effective_cache_size< / code > < / li >
< li > < code > work_mem< / code > < / li >
< li > < code > maintenance_work_mem< / code > < / li >
< li > < code > autovacuum_work_mem< / code > < / li >
< / ul >
< p > Note that the appropriate values for those fields depend on the amount
of free memory the database host has available.< / p >
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< p > Additionally, admins of large deployments might want to consider using huge pages
to help manage memory, especially when using large values of < code > shared_buffers< / code > . You
can read more about that < a href = "https://www.postgresql.org/docs/10/kernel-resources.html#LINUX-HUGE-PAGES" > here< / a > .< / p >
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< h2 id = "porting-from-sqlite" > < a class = "header" href = "#porting-from-sqlite" > Porting from SQLite< / a > < / h2 >
< h3 id = "overview" > < a class = "header" href = "#overview" > Overview< / a > < / h3 >
< p > The script < code > synapse_port_db< / code > allows porting an existing synapse server
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backed by SQLite to using PostgreSQL. This is done as a two phase
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process:< / p >
< ol >
< li > Copy the existing SQLite database to a separate location and run
the port script against that offline database.< / li >
< li > Shut down the server. Rerun the port script to port any data that
has come in since taking the first snapshot. Restart server against
the PostgreSQL database.< / li >
< / ol >
< p > The port script is designed to be run repeatedly against newer snapshots
of the SQLite database file. This makes it safe to repeat step 1 if
there was a delay between taking the previous snapshot and being ready
to do step 2.< / p >
< p > It is safe to at any time kill the port script and restart it.< / p >
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< p > However, under no circumstances should the SQLite database be < code > VACUUM< / code > ed between
multiple runs of the script. Doing so can lead to an inconsistent copy of your database
into Postgres.
To avoid accidental error, the script will check that SQLite's < code > auto_vacuum< / code > mechanism
is disabled, but the script is not able to protect against a manual < code > VACUUM< / code > operation
performed either by the administrator or by any automated task that the administrator
may have configured.< / p >
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< p > Note that the database may take up significantly more (25% - 100% more)
space on disk after porting to Postgres.< / p >
< h3 id = "using-the-port-script" > < a class = "header" href = "#using-the-port-script" > Using the port script< / a > < / h3 >
< p > Firstly, shut down the currently running synapse server and copy its
database file (typically < code > homeserver.db< / code > ) to another location. Once the
copy is complete, restart synapse. For instance:< / p >
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< pre > < code class = "language-sh" > synctl stop
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cp homeserver.db homeserver.db.snapshot
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synctl start
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< / code > < / pre >
< p > Copy the old config file into a new config file:< / p >
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< pre > < code class = "language-sh" > cp homeserver.yaml homeserver-postgres.yaml
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< / code > < / pre >
< p > Edit the database section as described in the section < em > Synapse config< / em >
above and with the SQLite snapshot located at < code > homeserver.db.snapshot< / code >
simply run:< / p >
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< pre > < code class = "language-sh" > synapse_port_db --sqlite-database homeserver.db.snapshot \
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--postgres-config homeserver-postgres.yaml
< / code > < / pre >
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< p > The flag < code > --curses< / code > displays a coloured curses progress UI. (NOTE: if your terminal is too small the script will error out)< / p >
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< p > If the script took a long time to complete, or time has otherwise passed
since the original snapshot was taken, repeat the previous steps with a
newer snapshot.< / p >
< p > To complete the conversion shut down the synapse server and run the port
script one last time, e.g. if the SQLite database is at < code > homeserver.db< / code >
run:< / p >
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< pre > < code class = "language-sh" > synapse_port_db --sqlite-database homeserver.db \
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--postgres-config homeserver-postgres.yaml
< / code > < / pre >
< p > Once that has completed, change the synapse config to point at the
PostgreSQL database configuration file < code > homeserver-postgres.yaml< / code > :< / p >
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< pre > < code class = "language-sh" > synctl stop
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mv homeserver.yaml homeserver-old-sqlite.yaml
mv homeserver-postgres.yaml homeserver.yaml
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synctl start
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< / code > < / pre >
< p > Synapse should now be running against PostgreSQL.< / p >
< h2 id = "troubleshooting" > < a class = "header" href = "#troubleshooting" > Troubleshooting< / a > < / h2 >
< h3 id = "alternative-auth-methods" > < a class = "header" href = "#alternative-auth-methods" > Alternative auth methods< / a > < / h3 >
< p > If you get an error along the lines of < code > FATAL: Ident authentication failed for user " synapse_user" < / code > , you may need to use an authentication method other than
< code > ident< / code > :< / p >
< ul >
< li >
< p > If the < code > synapse_user< / code > user has a password, add the password to the < code > database:< / code >
section of < code > homeserver.yaml< / code > . Then add the following to < code > pg_hba.conf< / code > :< / p >
< pre > < code > host synapse synapse_user ::1/128 md5 # or `scram-sha-256` instead of `md5` if you use that
< / code > < / pre >
< / li >
< li >
< p > If the < code > synapse_user< / code > user does not have a password, then a password doesn't
have to be added to < code > homeserver.yaml< / code > . But the following does need to be added
to < code > pg_hba.conf< / code > :< / p >
< pre > < code > host synapse synapse_user ::1/128 trust
< / code > < / pre >
< / li >
< / ul >
< p > Note that line order matters in < code > pg_hba.conf< / code > , so make sure that if you do add a
new line, it is inserted before:< / p >
< pre > < code > host all all ::1/128 ident
< / code > < / pre >
< h3 id = "fixing-incorrect-collate-or-ctype" > < a class = "header" href = "#fixing-incorrect-collate-or-ctype" > Fixing incorrect < code > COLLATE< / code > or < code > CTYPE< / code > < / a > < / h3 >
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< p > Synapse will refuse to start when using a database with incorrect values of
< code > COLLATE< / code > and < code > CTYPE< / code > unless the config flag < code > allow_unsafe_locale< / code > , found in the
< code > database< / code > section of the config, is set to true. Using different locales can
cause issues if the locale library is updated from underneath the database, or
if a different version of the locale is used on any replicas.< / p >
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< p > If you have a database with an unsafe locale, the safest way to fix the issue is to dump the database and recreate it with
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the correct locale parameter (as shown above). It is also possible to change the
parameters on a live database and run a < code > REINDEX< / code > on the entire database,
however extreme care must be taken to avoid database corruption.< / p >
< p > Note that the above may fail with an error about duplicate rows if corruption
has already occurred, and such duplicate rows will need to be manually removed.< / p >
< h3 id = "fixing-inconsistent-sequences-error" > < a class = "header" href = "#fixing-inconsistent-sequences-error" > Fixing inconsistent sequences error< / a > < / h3 >
< p > Synapse uses Postgres sequences to generate IDs for various tables. A sequence
and associated table can get out of sync if, for example, Synapse has been
downgraded and then upgraded again.< / p >
< p > To fix the issue shut down Synapse (including any and all workers) and run the
SQL command included in the error message. Once done Synapse should start
successfully.< / p >
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