Steps to Invoke AWS Lambda as SQL Functions

Shows the steps to invoke AWS remote functions as SQL functions in your database.

To invoke AWS Lambda as SQL functions, we will be creating a catalog of SQL wrapper functions that reference and call their respective cloud function via their API endpoints. Before you create this catalog, it is assumed here that you have created the necessary cloud functions to be referenced by this catalog.

Note

To access AWS lambda functions you need to configure the necessary policies. See Creating an IAM policy to access AWS Lambda resources and Using resource-based policies for Lambda for more information.

Create a credential using the procedure DBMS_CLOUD.CREATE_CREDENTIAL. The credential object that you are creating must be of type secret key.
```
SET DEFINE OFF
BEGIN
  DBMS_CLOUD.CREATE_CREDENTIAL (
    credential_name => 'AWS_CRED',
    username        => 'access_key_ID',
    password        => 'secret_access_key'
  );
END;
/
```
This creates the AWS_CRED credential.

See CREATE_CREDENTIAL Procedure for more information.
Create a catalog.

A catalog is a collection of wrapper functions that reference and call their respective cloud functions via their API endpoints.
Example to create a catalog for AWS functions.
```
BEGIN
    DBMS_CLOUD_FUNCTION.CREATE_CATALOG (
        credential_name  => 'AWS_CRED', 
        catalog_name     => 'AWS_DEMO_CATALOG', 
        service_provider => 'AWS',
        cloud_params     => '{"region_id":"ap-northeast-1"}'
 );
END;
/

PL/SQL procedure successfully completed.
```
This creates the AWS_DEMO_CATALOG catalog.

See CREATE_CATALOG Procedure for more information. You can query DBA_CLOUD_FUNCTION_CATALOG View and USER_CLOUD_FUNCTION_CATALOG View views to retrieve the list of all the catalogs in your database.

You can list the functions in a catalog.

Following is the example to list AWS Lambda functions:

VAR function_list CLOB;

BEGIN
 DBMS_CLOUD_FUNCTION.LIST_FUNCTIONS (
    credential_name  => 'AWS_CRED',
    catalog_name     => 'AWS_DEMO_CATALOG',
    function_list    => :function_list
);
END;
/

PL/SQL procedure successfully completed.

SELECT JSON_QUERY (:function_list, '$' RETURNING VARCHAR2(32676) pretty) AS search_results FROM dual;

SEARCH_RESULTS                        --This is a sample output
------------------------------------------------------------------------------------------------
[
  {
    "functionName"   : "test3_example",
    "functionArn"    : "arn:aws:lambda:ap-north-1:378:func:test3_example",
    "invokeEndpoint" : "https://swiy3.lambda-url.ap-north-1.on.aws_example/"
  },
  {
    "functionName"   : "SumOfNum_example",
    "functionArn"    : "arn:aws:lambda:ap-north-1:378:func:SumOfNum_example"

SEARCH_RESULTS
---------------------------------------------------------------------------------------------------
    "invokeEndpoint" : "https://swiy3.lambda-url.ap-north-1.on.aws_example/"
  },
  {
    "functionName"   : "testlambda_example",
    "functionArn"    : "arn:aws:lambda:ap-north-1:378:func:testlambda_example",
    "invokeEndpoint" : "https://swiy3.lambda-url.ap-north-1.on.aws_example/"
  },

SEARCH_RESULTS
---------------------------------------------------------------------------------------------------
  {
    "functionName"   : "hellp-python_example",
    "functionArn"    : "arn:aws:lambda:ap-north-1:378:func:hellp-python_example",
    "invokeEndpoint" : "https://swiy3.lambda-url.ap-north-1.on.aws_example/"
  },
  {
    "functionName"   : "testlam_example",
    "functionArn"    : "arn:aws:lambda:ap-north-1:378:func:testlam_example",

SEARCH_RESULTS
---------------------------------------------------------------------------------------------------
    "invokeEndpoint" : "https://swiy3.lambda-url.ap-north-1.on.aws_example/"
  }
]

See LIST_FUNCTIONS Procedure for more information.

Run the DBMS_CLOUD_FUNCTION.SYNC_FUNCTIONS to create wrapper SQL functions. You can use one of the following methods to create the wrapper SQL functions in the catalog, that call their respective cloud functions:
- SYNC_FUNCTIONS: SYNC_FUNCTIONS is the quickest and simplest method, which automatically syncs (creates or deletes) wrapper functions in the catalog with the complete list of cloud functions defined in the region, compartment, and tenancy with which the catalog was created. For example:
```
BEGIN
 DBMS_CLOUD_FUNCTION.SYNC_FUNCTIONS (
        catalog_name => 'AWS_DEMO_CATALOG'
 );
END;
/
PL/SQL procedure successfully completed.
```
This creates a PL/SQL wrapper for adding new functions to the catalog and removing wrappers for functions that have been deleted from the catalog.
Run the following query to verify the sync.
```
SELECT object_name FROM sys.all_objects WHERE owner='TEST_USER' AND object_type='FUNCTION';


OBJECT_NAME
--------------------------------------------------------------------------------
TESTLAMBDA
HELLP-PYTHON
TESTLAM
TEST3
SUMOFNUMBERS
```
Note

Keep a note of the current user in order to run this command.

See SYNC_FUNCTIONS Procedure for more information.
- You can manually create a SQL Function in your catalog that calls its respective cloud function using DBMS_CLOUD.CREATE_FUNCTION.
Example to create a function in the AWS_DEMO_CATALOG catalog.
```
BEGIN
DBMS_CLOUD_FUNCTION.CREATE_FUNCTION (
  credential_name => 'AWS_CRED',
  catalog_name    => 'AWS_DEMO_CATALOG', 
  function_name   => 'aws_testlambda', 
  function_id     => 'arn:aws:lambda:ap-northeast-1:378079562280:function:hellp-python'
);
END;
/
PL/SQL procedure successfully completed.
```
This creates the AWS_TESTLAMBDA function in the AWS_DEMO_CATALOG catalog.
The AWS_TESTLAMBDA function in the catalog is a reference to the respective cloud function whose endpoint is referenced by the FUNCTION_ID parameter. Invoking the function in the catalog along with its arguments runs the corresponding cloud function and provides the output returned by the cloud function.

You can query DBA_CLOUD_FUNCTION View and USER_CLOUD_FUNCTION View views to retrieve the list of all the functions in your database.

See CREATE_FUNCTION Procedure for more information.

After the function is created you can DESCRIBE and invoke it.

DESC AWS_TESTLAMBDA
COLUMN STATUS format a30
COLUMN OUTPUT format a30

SELECT AWS_TESTLAMBDA(NULL) FROM dual;

AWS_TESTLAMBDA(NULL)
----------------------------------------------------
{"STATUS":"200","RESPONSE_BODY":"Hello Python!!"}

This invokes the AWS_TESTLAMBDA function by calling the function reference arn:aws:lambda:ap-northeast-1:378079562280:function:hellp-python in the AWS_DEMO_CATALOG catalog.

You can drop an existing function using DROP_FUNCTION procedure. For example:
```
EXEC DBMS_CLOUD_FUNCTION.DROP_FUNCTION (CATALOG_NAME => 'AWS_DEMO_CATALOG', FUNCTION_NAME => 'AWS_TESTLAMBDA');

PL/SQL procedure successfully completed.
```
This drops the AWS_TESTLAMBDA function from the AWS_DEMO_CATALOG catalog.

See DROP_FUNCTION Procedure for more information.
You can drop an existing catalog using DROP_CATALOG procedure. For example:
```
BEGIN
    DBMS_CLOUD_FUNCTION.DROP_CATALOG (
      catalog_name     => 'AWS_DEMO_CATALOG'
  );
END;
/

PL/SQL procedure successfully completed.
```
This drops the AWS_DEMO_CATALOG from your database.

See DROP_CATALOG Procedure for more information.

Parent topic: Invoke User Defined Functions

Oracle Cloud Infrastructure Documentation