Overview
This node integrates with Amazon QLDB (Quantum Ledger Database) to perform various database operations on a specified ledger and table. It supports selecting, inserting, updating, upserting (create or update), running direct queries, and retrieving all records from the ledger's table.
Common scenarios where this node is beneficial include:
- Managing immutable ledger data for financial transactions or audit logs.
- Querying and updating records in a cryptographically verifiable ledger.
- Automating data workflows that require ledger consistency and integrity.
Practical examples:
- Updating user account balances in a financial ledger.
- Inserting new transaction records into a blockchain-like ledger.
- Running custom queries to extract audit trails or compliance reports.
Properties
| Name | Meaning |
|---|---|
| Ledger | Name of the ledger to connect to within Amazon QLDB. |
| Table | Name of the table (also called a database) inside the ledger where operations are performed. |
| Operation | The action to perform: - All (select all records) - Create (insert record) - Create or Update (upsert) - Direct Query (custom QLDB SQL query) - Select (query records) - Update (update records) |
| Direct Query | A custom QLDB SQL query string (shown only if Operation is "Direct Query"). |
| Where | JSON object representing the filter criteria for select, update, or upsert operations. |
| Document | JSON object containing the document data for insert, update, or upsert operations. |
| Flatten Results | Boolean flag indicating whether to unpack document updates; may change the number of outputs. |
Output
The node outputs an array of JSON objects under the json field. Each object corresponds to the result of the executed operation and contains the relevant records or confirmation of changes made.
- For select and query operations, it returns the matched documents.
- For insert, update, and upsert operations, it returns the affected documents after the operation.
- If "Flatten Results" is enabled, the output array is flattened so each document is a separate item in the output.
The node does not explicitly output binary data.
Dependencies
- Requires valid AWS credentials with permissions to access Amazon QLDB.
- Needs configuration of AWS region and authentication via an API key credential.
- Uses the Amazon QLDB SDK internally to execute commands against the ledger.
Troubleshooting
- Invalid JSON in "Where" or "Document" fields: The node expects valid JSON strings for these inputs. Malformed JSON will cause parsing errors. Ensure proper JSON formatting.
- Authentication errors: If AWS credentials are missing or incorrect, the node will fail to connect. Verify that the API key credential is correctly configured with appropriate permissions.
- Operation-specific errors: For example, attempting to update records without specifying a valid "Where" clause may result in no records being updated or errors.
- Flatten Results side effects: Enabling flattening can produce more or fewer output items than input items, which might affect downstream nodes expecting a 1:1 correspondence.