The PostgreSQL connector allows querying and creating tables in an external PostgreSQL database. This can be used to join data between different systems like PostgreSQL and Hive, or between different PostgreSQL instances.
To connect to PostgreSQL, you need:
PostgreSQL 9.6 or higher.
Network access from the Trino coordinator and workers to PostgreSQL. Port 5432 is the default port.
The connector can query a database on a PostgreSQL server. Create a catalog
properties file that specifies the PostgreSQL connector by setting the
For example, to access a database as the
postgresqlsdb catalog, create the
etc/catalog/postgresqlsdb.properties. Replace the connection properties
as appropriate for your setup:
connector.name=postgresql connection-url=jdbc:postgresql://example.net:5432/database connection-user=root connection-password=secret
connection-url defines the connection information and parameters to pass
to the PostgreSQL JDBC driver. The parameters for the URL are available in the
PostgreSQL JDBC driver documentation. Some parameters
can have adverse effects on the connector behavior or not work with the
connection-password are typically required and
determine the user credentials for the connection, often a service user. You can
use secrets to avoid actual values in the catalog
Multiple PostgreSQL databases or servers#
The PostgreSQL connector can only access a single database within a PostgreSQL server. Thus, if you have multiple PostgreSQL databases, or want to connect to multiple PostgreSQL servers, you must configure multiple instances of the PostgreSQL connector.
To add another catalog, simply add another properties file to
with a different name, making sure it ends in
.properties. For example,
if you name the property file
sales.properties, Trino creates a
sales using the configured connector.
Decimal type handling#
DECIMAL types with precision larger than 38 can be mapped to a Trino
by setting the
decimal-mapping configuration property or the
decimal_mapping session property to
allow_overflow. The scale of the resulting type is controlled via the
configuration property or the
decimal-rounding-mode session property. The precision is always 38.
By default, values that require rounding or truncation to fit will cause a failure at runtime. This behavior
is controlled via the
decimal-rounding-mode configuration property or the
property, which can be set to
UNNECESSARY (the default),
Array type handling#
The PostgreSQL array implementation does not support fixed dimensions whereas Trino
support only arrays with fixed dimensions.
You can configure how the PostgreSQL connector handles arrays with the
postgresql.array-mapping configuration property in your catalog file
array_mapping session property.
The following values are accepted for this property:
DISABLED(default): array columns are skipped.
AS_ARRAY: array columns are interpreted as Trino
ARRAYtype, for array columns with fixed dimensions.
AS_JSON: array columns are interpreted as Trino
JSONtype, with no constraint on dimensions.
General configuration properties#
The following properties can be used to configure how data types from the connected data source are mapped to Trino data types and how the metadata is cached in Trino.
Configure how unsupported column data types are handled:
The respective catalog session property is
Allow forced mapping of comma separated lists of data types to convert to
Support case insensitive database and collection names
Duration for which metadata, including table and column statistics, is cached
0 (disabled caching)
Cache the fact that metadata, including table and column statistics, is not available
The PostgreSQL connector provides a schema for every PostgreSQL schema.
You can see the available PostgreSQL schemas by running
SHOW SCHEMAS FROM postgresql;
If you have a PostgreSQL schema named
web, you can view the tables
in this schema by running
SHOW TABLES FROM postgresql.web;
You can see a list of the columns in the
clicks table in the
using either of the following:
DESCRIBE postgresql.web.clicks; SHOW COLUMNS FROM postgresql.web.clicks;
Finally, you can access the
clicks table in the
SELECT * FROM postgresql.web.clicks;
If you used a different name for your catalog properties file, use
that catalog name instead of
postgresql in the above examples.
The connector provides read access and write access to data and metadata in PostgreSQL. In addition to the globally available and read operation statements, the connector supports the following features:
WHERE clause is specified, the
DELETE operation only works if the
predicate in the clause can be fully pushed down to the data source.
The connector supports pushdown for a number of operations:
Aggregate pushdown for the following functions: