FaqueLDB

The Fake Ledger Database

FaqueLDB is a testing-oriented in-memory database that aims to be a drop-in replacement for Amazon Quantum Ledger Database (QLDB). To this end, it supports PartiQL queries and serializes data using the Amazon Ion format.

Support

FaqueLDB currently supports:

• Transactions
  • Full journal with verifiable hashes
  • Commit or abort transactions
  • Committed views (_ql_committed_*)
• SELECT Queries:
  • Everything supported by the PartiQL reference implementation, including conditionals, joins, and navigating nested data structures
  • The BY clause to retrieve document IDs
  • The system catalog (information_schema)
• Functions:
  • Aggregations (COUNT, MAX, etc.)
  • Casts (CAST, TO_STRING, etc.)
  • Null handling (COALESCE, etc.)
  • Date/time (UTCNOW, etc.)
  • String utilities (TRIM, UPPER, etc.)
• DDL:
  • CREATE TABLE without tags
  • DROP TABLE
  • CREATE INDEX is implemented, but it doesn't affect query performance
• DML:
  • INSERT for single and multiple values

These features of QLDB are not currently supported, but are on the roadmap:

• DDL:
  • DROP INDEX does not support the WITH clause that is required by QLDB
  • UNDROP TABLE is not supported by the PartiQL reference parser yet
• DML:
  • DELETE
  • UPDATE
  • FROM...INSERT
  • FROM...REMOVE
  • FROM...SET
• Functions:
  • TXID
  • HISTORY
• Multiple ledgers

These features of QLDB are not supported and are low priority:

• The control plane and all its features, including ledger management, exports, streams, and tags

Usage

Run

Start Server (Docker)

docker run --rm -p 8000:8000 cimbul/faqueldb

Start Server (Local)

$ ./gradlew run

Run Queries

Using the QLDB Shell:

$ qldb -s http://localhost:8000 -l test
qldbshell > create table foo
qldbshell > insert into foo << {'x': 1}, {'x': 2} >>
qldbshell > select * from foo

Test

$ ./gradlew test