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 configure the PostgreSQL connector, create a catalog properties file
etc/catalog named, for example,
mount the PostgreSQL connector as the
Create the file with the following contents, replacing 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
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, Presto creates a
sales using the configured connector.
Decimal Type Handling#
DECIMAL types with precision larger than 38 can be mapped to a Presto
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 Presto
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 Presto
ARRAYtype, for array columns with fixed dimensions.
AS_JSON: array columns are interpreted as Presto
JSONtype, with no constraint on dimensions.
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 supports pushdown for processing the following aggregate functions:
The following SQL statements are not yet supported: