Database Connection Settings

Craft supports several database connection settings that give you control over how Craft connects to the database.

Ultimately, database connection settings must be set from config/db.php, but we recommend you initially set them as environment variables (such as in your .env file), and then pull the environment variable value into config/db.php using getenv().

For example, in a new Craft 3 project, your .env file should define these environment variables:

ENVIRONMENT="dev"
SECURITY_KEY=""
DB_DRIVER="mysql"
DB_SERVER="<host>"
DB_PORT="<port>"
DB_DATABASE="<dbname>"
DB_USER="root"
DB_PASSWORD=""
DB_SCHEMA="public"
DB_TABLE_PREFIX=""

The variables that start with DB_ are database connection settings, and they get pulled into config/db.php like this:

return [
    'driver' => getenv('DB_DRIVER'),
    'server' => getenv('DB_SERVER'),
    'port' => getenv('DB_PORT'),
    'database' => getenv('DB_DATABASE'),
    'user' => getenv('DB_USER'),
    'password' => getenv('DB_PASSWORD'),
    'schema' => getenv('DB_SCHEMA'),
    'tablePrefix' => getenv('DB_TABLE_PREFIX'),
];

You may also provide a DB_DSN environment variable. If defined, Craft will use that.

We recommend this environment variable approach for two reasons:

1. It keeps sensitive information out of your project’s codebase. (.env files should never be shared or committed to Git.)
2. It makes collaborating with other developers easier, as each developer can define their own settings without overwriting someone else’s settings.

Here’s the full list of database connection settings that Craft supports:

#attributes

An array of key => value pairs of PDO attributes to pass into the PDO constructor.

For example, when using the MySQL PDO driver, if you wanted to enable a SSL database connection (assuming SSL is enabled in MySQL and 'user' can connect via SSL, you’d set these:

[
    PDO::MYSQL_ATTR_SSL_KEY    => '/path/to/my/client-key.pem',
    PDO::MYSQL_ATTR_SSL_CERT   => '/path/to/my/client-cert.pem',
    PDO::MYSQL_ATTR_SSL_CA     => '/path/to/my/ca-cert.pem',
],

#charset

The charset to use when creating tables.

::: tip You can change the character set and collation across all existing database tables using this terminal command:

> php craft db/convert-charset

:::

#collation

The collation to use when creating tables.

This is only used by MySQL. If null, the charset’s default collation will be used.

| Charset | Default collation | | --------- | -------------------- | | utf8 | utf8_general_ci | | utf8mb4 | utf8mb4_0900_ai_ci |

::: tip You can change the character set and collation across all existing database tables using this terminal command:

> php craft db/convert-charset

:::

#database

The name of the database to select.

#driver

The database driver to use. Either mysql for MySQL or pgsql for PostgreSQL.

#dsn

The Data Source Name (“DSN”) that tells Craft how to connect to the database.

DSNs should begin with a driver prefix (mysql: or pgsql:), followed by driver-specific parameters. For example, mysql:host=127.0.0.1;port=3306;dbname=acme_corp.

• MySQL parameters: https://php.net/manual/en/ref.pdo-mysql.connection.php
• PostgreSQL parameters: https://php.net/manual/en/ref.pdo-pgsql.connection.php

#password

The database password to connect with.

#port

The database server port. Defaults to 3306 for MySQL and 5432 for PostgreSQL.

#schema

The schema that Postgres is configured to use by default (PostgreSQL only).

::: tip To force Craft to use the specified schema regardless of PostgreSQL’s search_path setting, you must enable the setSchemaOnConnect setting. :::

#server

The database server name or IP address. Usually localhost or 127.0.0.1.

#setSchemaOnConnect

Whether the schema should be explicitly used for database queries (PostgreSQL only).

::: warning This will cause an extra SET search_path SQL query to be executed per database connection. Ideally, PostgreSQL’s search_path setting should be configured to prioritize the desired schema. :::

#tablePrefix

If you’re sharing Craft installs in a single database (MySQL) or a single database and using a shared schema (PostgreSQL), you can set a table prefix here to avoid per-install table naming conflicts. This can be no more than 5 characters, and must be all lowercase.

#unixSocket

MySQL only. If this is set, the CLI connection string (used for yiic) will connect to the Unix socket instead of the server and port. If this is specified, then server and port settings are ignored.

#url

The database connection URL, if one was provided by your hosting environment.

If this is set, the values for driver, user, database, server, port, and database will be extracted from it.

#useUnbufferedConnections

Whether batched queries should be executed on a separate, unbuffered database connection.

This setting only applies to MySQL. It can be enabled when working with high volume content, to prevent PHP from running out of memory when querying too much data at once. (See https://www.yiiframework.com/doc/guide/2.0/en/db-query-builder#batch-query-mysql for an explanation of MySQL’s batch query limitations.)

#user

The database username to connect with.