adk-postgres — Persistence Layer Overview

Why Postgres

• Transactional session writes — commit or roll back cleanly.
• JSONB for flexible message shapes without schema migrations on every change.
• Universal deployment — no team is scared of installing Postgres.
• Rich indexing (GIN on JSONB) makes memory queries fast enough for chat.

What gets persisted

• Sessions (row per session, JSONB for metadata).
• Messages (row per turn, ordered by ts).
• Events (structured audit log of every runtime decision).
• Task state (for long-running / paused tasks).

Plugging in

PostgresSessionStore store = PostgresSessionStore.builder()
    .dataSource(dataSource)
    .tablePrefix("adk_")
    .build();

runtime.setSessionStore(store);