Adopt SlateDB

[em3s]

Background

Long-lived tracker for adopting SlateDB as a storage backend. Three exploratory rounds confirmed SlateDB integrates cleanly with actionbase; each closed without merge as the timing on our side wasn't quite right. SlateDB continues to evolve at its own pace, and we'll meet it when our groundwork is ready.

Task

• Prerequisites land (Java 25 v0.5.0, metastore v0.6.0, storage backend abstraction Introduce StorageBackend abstraction layer #173 / Replace DefaultHBaseCluster with DefaultStorageBackendFactory #175)
• Re-verify the port against the then-current slatedb-uniffi release
• Promote to an Adopt SlateDB milestone
• Land adoption via PRs from the preserved next/slatedb-uniffi branch

Done When

SlateDB is available as a supported storage backend in actionbase.

Notes

Each round explored a different facet of the integration and confirmed the pieces fit. When our side is ready, picking the work back up should be a matter of resuming rather than redoing.

• Explore SlateDB as a storage backend #163 — first look at SlateDB as a storage backend. Verified the SlateDBDatastoreCompatibilityTest suite passes; built initial SlateDbHashLabel / SlateDbIndexedLabel implementations.
• Experiment with Java 24+ for SlateDB integration #155 — followed upstream's move to Java 24+ FFM (jextract) bindings. Experimental integration landed across SlateDB storage backend integration #164 / Migrate to upstream slatedb-java bindings #167 / Add SlateDB compatibility test #170.
• Port SlateDB integration to 0.12.x UniFFI bindings #280 — ported the integration to the newer UniFFI 0.12.x bindings (io.slatedb:slatedb-uniffi). All SlateDB unit tests and the compatibility suite passed locally.

The work from each round is preserved on the closed PRs and on next/slatedb-uniffi.