Module diesel::pg

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Available on crate feature postgres_backend only.
Expand description

Provides types and functions related to working with PostgreSQL

Much of this module is re-exported from database agnostic locations. However, if you are writing code specifically to extend Diesel on PostgreSQL, you may need to work with this module directly.


Data structures for PG types which have no corresponding Rust type

PostgreSQL related query builder extensions

PostgreSQL specific SQL types


Represents DISTINCT ON (...)


This error indicates that a type lookup for a custom postgres type failed

The PostgreSQL backend


The connection string expected by PgConnection::establish should be a PostgreSQL connection string, as documented at


Cache for the OIDs of custom Postgres types


The key used to lookup cached type oid’s inside of a PgMetadataCache.

The PostgreSQL query builder

A PgConnection specific loading mode to load rows one by one

The OIDs for a SQL type

Raw postgres value as received from the database

Used to build a transaction, specifying additional details.



Gets the PgMetadataCache for a Connection<Backend=Pg> so that the lookup of user defined types, or types which come from an extension can be cached.

Determines the OID of types at runtime


This is a helper trait to defer a type oid lookup to a later point in time