PostgreSQL Connector#

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 two different PostgreSQL instances.

Configuration#

To configure the PostgreSQL connector, create a catalog properties file in etc/catalog named, for example, postgresql.properties, to mount the PostgreSQL connector as the postgresql catalog. 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 etc/catalog with a different name (making sure it ends in .properties). For example, if you name the property file sales.properties, Presto will create a catalog named sales using the configured connector.

General Configuration Properties#

Property Name

Description

Default

user-credential-name

Name of the extraCredentials property whose value is the JDBC driver’s user name. See extraCredentials in Parameter Reference.

password-credential-name

Name of the extraCredentials property whose value is the JDBC driver’s user password. See extraCredentials in Parameter Reference.

case-insensitive-name-matching

Match dataset and table names case-insensitively.

false

case-insensitive-name-matching.cache-ttl

Duration for which remote dataset and table names will be cached. Set to 0ms to disable the cache.

1m

Querying PostgreSQL#

The PostgreSQL connector provides a schema for every PostgreSQL schema. You can see the available PostgreSQL schemas by running SHOW SCHEMAS:

SHOW SCHEMAS FROM postgresql;

If you have a PostgreSQL schema named web, you can view the tables in this schema by running SHOW TABLES:

SHOW TABLES FROM postgresql.web;

You can see a list of the columns in the clicks table in the web database using either of the following:

DESCRIBE postgresql.web.clicks;
SHOW COLUMNS FROM postgresql.web.clicks;

Finally, you can access the clicks table in the web schema:

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.

Type mapping#

PrestoDB and PostgreSQL each support types that the other does not. When reading from or writing to PostgreSQL, Presto converts the data types from PostgreSQL to equivalent Presto data types, and from Presto to equivalent PostgreSQL data types.

PostgreSQL to PrestoDB type mapping#

The connector maps PostgreSQL types to the corresponding PrestoDB types:

PostgreSQL to PrestoDB type mapping#

PostgreSQL type

PrestoDB type

BIT

BOOLEAN

BOOLEAN

BOOLEAN

SMALLINT

SMALLINT

INTEGER

INTEGER

BIGINT

BIGINT

DOUBLE PRECISION

DOUBLE

REAL

REAL

NUMERIC(p, s)

DECIMAL(p, s)

CHAR(n)

CHAR(n)

VARCHAR(n)

VARCHAR(n)

ENUM

VARCHAR

BYTEA

VARBINARY

DATE

DATE

TIME

TIME

TIMESTAMP

TIMESTAMP

TIMESTAMPTZ

TIMESTAMP

MONEY

DOUBLE

UUID

UUID

JSON

JSON

JSONB

JSON

No other types are supported.

PrestoDB to PostgreSQL type mapping#

The connector maps PrestoDB types to the corresponding PostgreSQL types:

PrestoDB to PostgreSQL type mapping#

PrestoDB type

PostgreSQL type

BOOLEAN

BOOLEAN

SMALLINT

SMALLINT

INTEGER

INTEGER

BIGINT

BIGINT

DOUBLE

DOUBLE PRECISION

DECIMAL(p, s)

NUMERIC(p, s)

CHAR(n)

CHAR(n)

VARCHAR(n)

VARCHAR(n)

VARBINARY

BYTEA

DATE

DATE

TIME

TIME

TIMESTAMP

TIMESTAMP

UUID

UUID

No other types are supported.

Tables with Unsupported Columns#

If you query a PostgreSQL table with the Presto connector, and the table either has no supported columns or contains only unsupported data types, Presto returns an error similar to the following example:

Query 20231120_102910_00004_35dqb failed: Table 'public.unsupported_type_table' has no supported columns (all 1 columns are not supported).

PostgreSQL Connector Limitations#

The following SQL statements are not yet supported: