Documentation

A single connection to the database.

Establish a connection according to the provided settings.

The first argument is an Adapter, which defines the backend implementation used to talk to PostgreSQL (for example, libpq via the pqi-ffi package, or a pure Haskell implementation via the pqi-native package). This is the only place in the library where users choose the adapter.

This function:

• Opens a PostgreSQL connection using the constructed connection string.
• Validates that the connection is healthy.
• Checks the server version for compatibility.
• Initializes session-level settings (encoding and message verbosity).

On success, returns a Connection wrapped in Right. On failure, returns a classified AcquireError in Left.

Release the connection.

Idempotent: releasing a connection that is already gone - released before, or finished by use - does nothing.

Execute a sequence of operations with exclusive access to the connection.

Blocks until the connection is available when there is another session running upon the connection on a different thread.

An exception thrown out of the session - including an interruption delivered from another thread, as timeout and killThread do - propagates, and the connection is finished on the way out. See the note on the exception path below for why it is not repaired instead.