Configure the database environment in which Mattermost is deployed by going to System Console > Environment > Database, or by editing the config.json file as described in the following tables. Changes to configuration settings in this section require a server restart before taking effect.

Driver name

Available in legacy Enterprise Edition E10/E20

The type of database. Can be either:

mysql: (Default) Enables driver to MySQL database.
postgres: Enables driver to PostgreSQL database.

System Config path: N/A
config.json setting: ".SqlSettings.DriverName",
Environment variable: MM_SQLSETTINGS_DRIVERNAME

Data source

Available in legacy Enterprise Edition E10/E20

The connection string to the master database.

String input.

System Config path: N/A
config.json setting: ".SqlSettings.DataSource",
Environment variable: MM_SQLSETTINGS_DATASOURCE

To enable SSL:

Add &tls=true to your database connection string if your SQL driver supports it.
Add &tls=skip-verify if you use self-signed certificates.

MySQL databases

When Driver Name is set to mysql, using collation is recommended over using charset.

To specify collation:

"SqlSettings": {
    "DataSource":
"<user:pass>@<servername>/mattermost?charset=utf8mb4,utf8&collation=utf8mb4_general_ci",
    [...]
 }

If collation is omitted, the default collation, utf8mb4_general_ci is used:

"SqlSettings": {
    "DataSource": "<user:pass>@<servername>/mattermost?charset=utf8mb4,utf8",
    [...]
 }

Note: If you’re using MySQL 8.0 or later, the default collation has changed to utf8mb4_0900_ai_ci. See our Database Software Requirements documentation for details on MySQL 8.0 support.

PostgreSQL databases

When Driver Name is set to postgres, use a connection string in the form of: postgres://mmuser:password@localhost:5432/mattermost_test?sslmode=disable&connect_timeout=10.

Maximum idle database connections

Available in legacy Enterprise Edition E10/E20

The maximum number of idle connections held open to the database.

Numerical input. Default is 10.

System Config path: Environment > Database
config.json setting: ".SqlSettings.MaxIdleConns": 10,
Environment variable: MM_SQLSETTINGS_MAXIDLECONNS

Maximum open connections

Available in legacy Enterprise Edition E10/E20

The maximum number of idle connections held open to the database.

Numerical input. Default is 300.

System Config path: Environment > Database
config.json setting: ".SqlSettings.MaxOpenConns": 300,
Environment variable: MM_SQLSETTINGS_MAXOPENCONNS

Query timeout

Available in legacy Enterprise Edition E10/E20

The amount of time to wait, in seconds, for a response from the database after opening a connection and sending the query.

Numerical input in seconds. Default is 30 seconds.

System Config path: Environment > Database
config.json setting: ".SqlSettings.QueryTimeout: 30",
Environment variable: MM_SQLSETTINGS_QUERYTIMEOUT

Maximum connection lifetime

Available in legacy Enterprise Edition E10/E20

Maximum lifetime for a connection to the database, in milliseconds. Use this setting to configure the maximum amount of time a connection to the database may be reused

Numerical input in milliseconds. Default is 3,600,000 milliseconds (1 hour).

System Config path: Environment > Database
config.json setting: ".SqlSettings.ConnMaxLifetimeMilliseconds: 3600000",
Environment variable: MM_SQLSETTINGS_CONNMAXLIFETIMEMILLISECONDS

Maximum connection idle timeout

Available in legacy Enterprise Edition E10/E20

Maximum time a database connection can remain idle, in milliseconds.

Numerical input in milliseconds. Default is 300000 (5 minutes).

System Config path: Environment > Database
config.json setting: ".SqlSettings.ConnMaxIdleTimeMilliseconds: 300000",
Environment variable: MM_SQLSETTINGS_CONNMAXIDLETIMEMILLISECONDS

Minimum hashtag length

Available in legacy Enterprise Edition E10/E20

Minimum number of characters in a hashtag. This value must be greater than or equal to 2.	System Config path: Environment > Database `config.json` setting: `".SqlSettings.MinimumHashtagLength: 3",` Environment variable: `MM_SQLSETTINGS_MINIMUMHASHTAGLENGTH`
Note: MySQL databases must be configured to support searching strings shorter than three characters. See the MySQL documentation for details.

SQL statement logging

Available in legacy Enterprise Edition E10/E20

Executed SQL statements can be written to the log for development.

true: Executing SQL statements are written to the log.
false: (Default) SQL statements aren’t written to the log.

System Config path: Environment > Database
config.json setting: ".SqlSettings.Trace: false",
Environment variable: MM_SQLSETTINGS_TRACE

Recycle database connections

Note

Available only on Enterprise plans

Available in legacy Enterprise Edition E20

Select the Recycle Database Connections button to reconnect to the configured database. All old connections are closed after 20 seconds.

To fail over without downing the server, change the database line in the config.json file, select Reload Configuration from Disk via Environment > Web Server, then select Recycle Database Connections.

System Config path: Environment > Database
config.json setting: N/A
Environment variable: N/A

Disable database search

Available in legacy Enterprise Edition E10/E20

When other search engines are configured, such as Elasticsearch, the database can be disabled to perform searches.

true: Disables the use of the database to perform searches. If another search engine isn’t configured, setting this value to true will result in empty search results.
false: (Default) Database search isn’t disabled.

System Config path: Environment > Database
config.json setting: ".SqlSettings.DisableDatabaseSearch: false",
Environment variable: MM_SQLSETTINGS_DISABLEDATABASESEARCH

Search behavior in Mattermost depends on which search engines are enabled.

When Elasticsearch is enabled, Mattermost will try to use it first.
If Elasticsearch fails or is disabled, Mattermost will attempt to use Bleve, if enabled. If this occurs, you will see the warning Encountered error on SearchPostsInTeamForUser.
If both Elasticsearch and Bleve fail or are disabled, Mattermost tries to search the database directly, if this is enabled.
If all of the above methods fail or are disabled, the search results will be empty.

Applied schema migrations

Available in legacy Enterprise Edition E10/E20

A list of all migrations that have been applied to the data store based on the version information available in the db_migrations table. Select About Mattermost from the product menu to review the current database schema version applied to your deployment.

Read replicas

Note

Available only on Enterprise and Professional plans

Available in legacy Enterprise Edition E10 and E20

Specifies the connection strings for the read replica databases.	System Config path: N/A `config.json` setting: `".SqlSettings.DataSourceReplicas": []` Environment variable: `MM_SQLSETTINGS_DATASOURCEREPLICAS`
Note: Each database connection string in the array must be in the same form used for the Data source setting.

Search replicas

Note

Available only on Enterprise and Professional plans

Available in legacy Enterprise Edition E10 and E20

Specifies the connection strings for the search replica databases. A search replica is similar to a read replica, but is used only for handling search queries.	System Config path: N/A `config.json` setting: `".SqlSettings.DataSourceSearchReplicas": []` Environment variable: `MM_SQLSETTINGS_DATASOURCESEARCHREPLICAS`
Note: Each database connection string in the array must be in the same form used for the Data source setting.

Replica lag settings

Note

Available only on Enterprise plans

Available in legacy Enterprise Edition E20

String array input specifies a connection string and user-defined SQL queries on the database to measure replica lag for a single replica instance.

These settings monitor absolute lag based on binlog distance/transaction queue length, and the time taken for the replica to catch up.

String array input consists of:

DataSource: The database credentials to connect to the replica instance.
QueryAbsoluteLag: A plain SQL query that must return a single row. The first column must be the node value of the Prometheus metric, and the second column must be the value of the lag used to measure absolute lag.
QueryTimeLag: A plain SQL query that must return a single row. The first column must be the node value of the Prometheus metric, and the second column must be the value of the lag used to measure the time lag.

System Config path: N/A
config.json setting: ".SqlSettings.ReplicaLagSettings": []
Environment variable: MM_SQLSETTINGS_REPLICALAGSETTINGS

Examples:

For AWS Aurora instances, QueryAbsoluteLag can be:

select server_id, highest_lsn_rcvd-durable_lsn as bindiff from aurora_global_db_instance_status() where server_id=<>

And for AWS Aurora instances, QueryTimeLag can be:

select server_id, visibility_lag_in_msec from aurora_global_db_instance_status() where server_id=<>

For MySQL Group Replication, the absolute lag can be measured from the number of pending transactions in the applier queue:

select member_id, count_transactions_remote_in_applier_queue FROM performance_schema.replication_group_member_stats where member_id=<>