Backend selection guide

Select from existing infrastructure and required semantics, then verify locally. Feature count alone is a poor decision rule.

Backend	Existing infrastructure / language	Transactions	Schema/index	Local verification	Portability note
Neo4j	Neo4j/Bolt, Cypher	native driver transaction	indexes and constraints	Testcontainers Neo4j 5	broad common-contract baseline
Memgraph	Memgraph with Neo4j-driver-compatible Bolt, Cypher	native transaction	backend-specific Cypher DDL	Memgraph container	test Cypher/schema differences
Apache AGE	PostgreSQL, Cypher-over-SQL	JDBC/Exposed boundary	limited portable DDL	apache/age:PG16_latest	SQL session and graph context matter
TinkerPop	in-process JVM, Gremlin/TinkerGraph	in-memory transaction behavior	manager capability is limited	no container	best for tests, not a remote-server substitute
FalkorDB	Redis-shaped service, openCypher subset	library/backend constraints	backend-specific indexes	FalkorDB container	validate unsupported transaction paths

Implementation and test anchors: Neo4j, Memgraph, AGE, TinkerGraph, FalkorDB.

Amazon Neptune is not implemented or supported in Graph 0.5.1. Do not infer support from roadmap or backlog issues. If portability matters, run the same domain example against candidate backends and record transaction, schema, ID, property-type, and traversal differences before selection.

Verify two finalists

Use the exact 0.5.1 test selectors, one backend at a time:

./gradlew :bluetape4k-graph-neo4j:test --tests '*Neo4jGraphMergeOperationsTest' --tests '*Neo4jGraphSchemaManagerTest'
./gradlew :bluetape4k-graph-memgraph:test --tests '*MemgraphGraphMergeOperationsTest' --tests '*MemgraphGraphSchemaManagerTest'
./gradlew :bluetape4k-graph-age:test --tests '*AgeGraphMergeOperationsTest' --tests '*AgeGraphSchemaManagerTest'
./gradlew :bluetape4k-graph-tinkerpop:test --tests '*TinkerGraphMergeOperationsTest' --tests '*TinkerGraphTransactionTest'
./gradlew :bluetape4k-graph-falkordb:test --tests '*FalkorDBGraphMergeOperationsTest' --tests '*FalkorDBGraphSchemaManagerTest'

Record container/image or in-memory fixture, created vertex/edge counts, duplicate merge outcome, rollback outcome, index/constraint inventory, and one shortestPath result. Inject an invalid identifier and a transaction exception. A candidate advances only if expected failure types and post-failure counts match the application’s recovery design. Finally repeat the same checks against the deployment server version and close resources according to fixture/caller ownership.