From relational to ledger - Amazon Quantum Ledger Database (Amazon QLDB)

From relational to ledger

Important

End of support notice: Existing customers will be able to use Amazon QLDB until end of support on 07/31/2025. For more details, see Migrate an Amazon QLDB Ledger to Amazon Aurora PostgreSQL.

If you're an application developer, you might have some experience using a relational database management system (RDBMS) and Structured Query Language (SQL). As you begin working with Amazon QLDB, you will encounter many similarities. As you progress to more advanced topics, you will also encounter powerful new features that QLDB has built on the RDBMS foundation. This section describes common database components and operations, comparing and contrasting them with their equivalents in QLDB.

The following diagram shows the mapping constructs of the core components between a traditional RDBMS and Amazon QLDB.

Diagram of core components of traditional RDBMS (database, table, index, row, column, etc.) mapping to corresponding QLDB components (ledger, table, index, Ion document, doc attribute, etc).

The following table shows the primary high-level similarities and differences of built-in operational features between a traditional RDBMS and QLDB.

Operation RDBMS QLDB
Creating tables CREATE TABLE statement that defines all column names and data types CREATE TABLE statement that doesn't define any table attributes or data types to allow schemaless and open content
Creating indexes CREATE INDEX statement CREATE INDEX statement for any top-level fields on a table
Inserting data INSERT statement that specifies values within a new row or tuple that adheres to the schema as defined by the table INSERT statement that specifies values within a new document in any valid Amazon Ion format regardless of the existing documents in the table
Querying data SELECT-FROM-WHERE statement SELECT-FROM-WHERE statement in the same syntax as SQL when querying flat documents
Updating data UPDATE-SET-WHERE statement UPDATE-SET-WHERE statement in the same syntax as SQL when updating flat documents
Deleting data DELETE-FROM-WHERE statement DELETE-FROM-WHERE statement in the same syntax as SQL when deleting flat documents
Nested and semistructured data Flat rows or tuples only Documents that can have any structured, semistructured, or nested data as supported by the Amazon Ion data format and the PartiQL query language
Querying metadata No built-in metadata SELECT statement that queries from the built-in committed view of a table
Querying revision history No built-in data history SELECT statement that queries from the built-in history function
Cryptographic verification No built-in cryptography or immutability APIs that return a digest of a journal and a proof that verifies the integrity of any document revision relative to that digest

For an overview of the core concepts and terminology in QLDB, see Core concepts.

For detailed information about the process of creating, querying, and managing your data in a ledger, see Working with data and history.