Prerequisites Limitations Terms Parameters Data type support Partitions and splits Performance Passthrough queries License information See also

Amazon Athena IBM Db2 connector

The Amazon Athena connector for Db2 enables Amazon Athena to run SQL queries on your IBM Db2 databases using JDBC.

Prerequisites

Deploy the connector to your AWS account using the Athena console or the AWS Serverless Application Repository. For more information, see Deploying a data source connector or Using the AWS Serverless Application Repository to deploy a data source connector.
Set up a VPC and a security group before you use this connector. For more information, see Creating a VPC for a data source connector.

Limitations

Write DDL operations are not supported.
In a multiplexer setup, the spill bucket and prefix are shared across all database instances.
Any relevant Lambda limits. For more information, see Lambda quotas in the AWS Lambda Developer Guide.
Date and timestamp data types in filter conditions must be cast to appropriate data types.

Terms

The following terms relate to the Db2 connector.

Database instance – Any instance of a database deployed on premises, on Amazon EC2, or on Amazon RDS.
Handler – A Lambda handler that accesses your database instance. A handler can be for metadata or for data records.
Metadata handler – A Lambda handler that retrieves metadata from your database instance.
Record handler – A Lambda handler that retrieves data records from your database instance.
Composite handler – A Lambda handler that retrieves both metadata and data records from your database instance.
Property or parameter – A database property used by handlers to extract database information. You configure these properties as Lambda environment variables.
Connection String – A string of text used to establish a connection to a database instance.
Catalog – A non-AWS Glue catalog registered with Athena that is a required prefix for the connection_string property.
Multiplexing handler – A Lambda handler that can accept and use multiple database connections.

Parameters

Use the Lambda environment variables in this section to configure the Db2 connector.

Connection string

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


dbtwo://${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.

Handler	Class
Composite handler	`Db2MuxCompositeHandler`
Metadata handler	`Db2MuxMetadataHandler`
Record handler	`Db2MuxRecordHandler`

Multiplexing handler parameters

Parameter	Description
`$catalog_connection_string`	Required. A database instance connection string. Prefix the environment variable with the name of the catalog used in Athena. For example, if the catalog registered with Athena is `mydbtwocatalog`, then the environment variable name is `mydbtwocatalog_connection_string`.
`default`	Required. The default connection string. This string is used when the catalog is `lambda:${AWS_LAMBDA_FUNCTION_NAME}`.

The following example properties are for a Db2 MUX Lambda function that supports two database instances: dbtwo1 (the default), and dbtwo2.

Property	Value
`default`	`dbtwo://jdbc:db2://dbtwo1.hostname:port/database_name:${secret1_name}`
`dbtwo_catalog1_connection_string`	`dbtwo://jdbc:db2://dbtwo1.hostname:port/database_name:${secret1_name}`
`dbtwo_catalog2_connection_string`	`dbtwo://jdbc:db2://dbtwo2.hostname:port/database_name:${secret2_name}`

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.

Connection String – A user name and password can be specified as properties in the JDBC connection string.

Important
As a security best practice, do not use hardcoded credentials in your environment variables or connection strings. For information about moving your hardcoded secrets to AWS Secrets Manager, see Move hardcoded secrets to AWS Secrets Manager in the AWS Secrets Manager User Guide.
AWS Secrets Manager – To use the Athena Federated Query feature with AWS Secrets Manager, the VPC connected to your Lambda function should have internet access or a VPC endpoint to connect to Secrets Manager.

You can put the name of a secret in AWS Secrets Manager in your JDBC connection string. The connector replaces the secret name with the username and password values from Secrets Manager.

For Amazon RDS database instances, this support is tightly integrated. If you use Amazon RDS, we highly recommend using AWS Secrets Manager and credential rotation. If your database does not use Amazon RDS, store the credentials as JSON in the following format:
```
{"username": "${username}", "password": "${password}"}
```

Example connection string with secret name

The following string has the secret name ${secret_name}.


dbtwo://jdbc:db2://hostname:port/database_name:${secret_name}

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


dbtwo://jdbc:db2://hostname:port/database_name:user=user_name;password=password;

Using a single connection handler

You can use the following single connection metadata and record handlers to connect to a single Db2 instance.

Handler type	Class
Composite handler	`Db2CompositeHandler`
Metadata handler	`Db2MetadataHandler`
Record handler	`Db2RecordHandler`

Single connection handler parameters

Parameter	Description
`default`	Required. The default connection string.

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 Db2 instance supported by a Lambda function.

Property	Value
`default`	dbtwo://jdbc:db2://hostname:port/`database_name`:${secret_name}

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.

Parameter	Description
`spill_bucket`	Required. Spill bucket name.
`spill_prefix`	Required. Spill bucket key prefix.
`spill_put_request_headers`	(Optional) A JSON encoded map of request headers and values for the Amazon S3 `putObject` request that is used for spilling (for example, `{"x-amz-server-side-encryption" : "AES256"}`). For other possible headers, see PutObject in the Amazon Simple Storage Service API Reference.

Data type support

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

Db2	Arrow
CHAR	VARCHAR
VARCHAR	VARCHAR
DATE	DATEDAY
TIME	VARCHAR
TIMESTAMP	DATEMILLI
DATETIME	DATEMILLI
BOOLEAN	BOOL
SMALLINT	SMALLINT
INTEGER	INT
BIGINT	BIGINT
DECIMAL	DECIMAL
REAL	FLOAT8
DOUBLE	FLOAT8
DECFLOAT	FLOAT8

Partitions and splits

A partition is represented by one or more partition columns of type varchar. The Db2 connector creates partitions using the following organization schemes.

Distribute by hash
Partition by range
Organize by dimensions

The connector retrieves partition details such as the number of partitions and column name from one or more Db2 metadata tables. Splits are created based upon the number of partitions identified.

Performance

The Athena Db2 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.

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 Db2 connector can combine these expressions and push them directly to Db2 for enhanced functionality and to reduce the amount of data scanned.

The following Athena Db2 connector operators support predicate pushdown:

Boolean: AND, OR, NOT
Equality: EQUAL, NOT_EQUAL, LESS_THAN, LESS_THAN_OR_EQUAL, GREATER_THAN, GREATER_THAN_OR_EQUAL, IS_DISTINCT_FROM, IS_NULL
Arithmetic: ADD, SUBTRACT, MULTIPLY, DIVIDE, MODULUS, NEGATE
Other: LIKE_PATTERN, IN

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 Db2 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 Db2, 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 Db2. 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'
        ))

License information

By using this connector, you acknowledge the inclusion of third party components, a list of which can be found in the pom.xml file for this connector, and agree to the terms in the respective third party licenses provided in the LICENSE.txt file on GitHub.com.