Amazon Athena PostgreSQL connector

The Amazon Athena PostgreSQL connector enables Athena to access your PostgreSQL databases.

This connector can be registered with Glue Data Catalog as a federated catalog. It supports data access controls defined in Lake Formation at the catalog, database, table, column, row, and tag levels. This connector uses Glue Connections to centralize configuration properties in Glue.

Prerequisites

Limitations

Terms

Parameters

Use the parameters in this section to configure the PostgreSQL connector.

Connection string

Use a JDBC connection string in the following format to connect to a database instance.

postgres://${jdbc_connection_string}

Using a multiplexing handler

You can use a multiplexer to connect to multiple database instances with a single Lambda function. Requests are routed by catalog name. Use the following classes in Lambda.

Multiplexing handler parameters

The following example properties are for a PostGreSql MUX Lambda function that supports two database instances: postgres1 (the default), and postgres2.

Providing credentials

To provide a user name and password for your database in your JDBC connection string, you can use connection string properties or AWS Secrets Manager.

Example connection string with secret name

The following string has the secret name ${Test/RDS/PostGres1}.

postgres://jdbc:postgresql://postgres1.host:5432/default?...&${Test/RDS/PostGres1}&...

The connector uses the secret name to retrieve secrets and provide the user name and password, as in the following example.

postgres://jdbc:postgresql://postgres1.host:5432/default?...&user=sample2&password=sample2&...

Currently, the PostgreSQL connector recognizes the user and password JDBC properties.

Enabling SSL

To support SSL in your PostgreSQL connection, append the following to your connection string:

&sslmode=verify-ca&sslfactory=org.postgresql.ssl.DefaultJavaSSLFactory

Example

The following example connection string does not use SSL.

postgres://jdbc:postgresql://example-asdf-aurora-postgres-endpoint:5432/asdf?user=someuser&password=somepassword

To enable SSL, modify the string as follows.

postgres://jdbc:postgresql://example-asdf-aurora-postgres-endpoint:5432/asdf?user=someuser&password=somepassword&sslmode=verify-ca&sslfactory=org.postgresql.ssl.DefaultJavaSSLFactory

Using a single connection handler

You can use the following single connection metadata and record handlers to connect to a single PostgreSQL instance.

Single connection handler parameters

The single connection handlers support one database instance and must provide a default connection string parameter. All other connection strings are ignored.

The following example property is for a single PostgreSQL instance supported by a Lambda function.

Spill parameters

The Lambda SDK can spill data to Amazon S3. All database instances accessed by the same Lambda function spill to the same location.

Data type support

The following table shows the corresponding data types for JDBC, PostGreSQL, and Arrow.

Partitions and splits

Partitions are used to determine how to generate splits for the connector. Athena constructs a synthetic column of type varchar that represents the partitioning scheme for the table to help the connector generate splits. The connector does not modify the actual table definition.

Performance

PostgreSQL supports native partitions. The Athena PostgreSQL connector can retrieve data from these partitions in parallel. If you want to query very large datasets with uniform partition distribution, native partitioning is highly recommended.

The Athena PostgreSQL connector performs predicate pushdown to decrease the data scanned by the query. LIMIT clauses, simple predicates, and complex expressions are pushed down to the connector to reduce the amount of data scanned and decrease query execution run time. However, selecting a subset of columns sometimes results in a longer query execution runtime.

LIMIT clauses

A LIMIT N statement reduces the data scanned by the query. With LIMIT N pushdown, the connector returns only N rows to Athena.

Predicates

A predicate is an expression in the WHERE clause of a SQL query that evaluates to a Boolean value and filters rows based on multiple conditions. The Athena PostgreSQL connector can combine these expressions and push them directly to PostgreSQL for enhanced functionality and to reduce the amount of data scanned.

The following Athena PostgreSQL connector operators support predicate pushdown:

Combined pushdown example

For enhanced querying capabilities, combine the pushdown types, as in the following example:

SELECT * 
FROM my_table 
WHERE col_a > 10 
    AND ((col_a + col_b) > (col_c % col_d))
    AND (col_e IN ('val1', 'val2', 'val3') OR col_f LIKE '%pattern%') 
LIMIT 10;

Passthrough queries

The PostgreSQL connector supports passthrough queries. Passthrough queries use a table function to push your full query down to the data source for execution.

To use passthrough queries with PostgreSQL, you can use the following syntax:

SELECT * FROM TABLE(
        system.query(
            query => 'query string'
        ))

The following example query pushes down a query to a data source in PostgreSQL. The query selects all columns in the customer table, limiting the results to 10.

SELECT * FROM TABLE(
        system.query(
            query => 'SELECT * FROM customer LIMIT 10'
        ))

Additional resources

For the latest JDBC driver version information, see the pom.xml file for the PostgreSQL connector on GitHub.com.

For additional information about this connector, visit the corresponding site on GitHub.com.