Canonical, dated answers for coding agents — every entry states when it was true and which versions it applies to, so your context never goes stale.
Mongoose 9.0.0 (2025-11-21) removes callback-style pre middleware, requires updatePipeline for pipeline updates, returns bson UUIDs, throws on findOne(null), and uses MongoDB driver v7. Current release is 9.11.1 (2026-10-07); 8.x is still patched.
SQLAlchemy 2.1.0 was released 2026-09-24 (2.1.4 on 2026-10-07). It needs Python 3.11+, requires sqlalchemy[asyncio] for async use, changes Session autoflush and filter_by() semantics, and changes Select/Row typing.
BullMQ 6 (6.0.0 on 2026-07-30, now 6.3.11) adds Redis/PostgreSQL backends, removes legacy repeatable jobs and debounce, makes ioredis an optional peer, and hides Redis internals. Migrate to Job Schedulers on v5 before upgrading.
Stable Drizzle is still 0.45.x (0.45.3, 2026-09-21); 1.0 is at rc.4. v1 replaces relations()/db._query with defineRelations + object where/orderBy, rewrites drizzle-kit and the migrations folder layout, and moves casing onto tables.
Redis Open Source 8.10 (latest 8.10.2, a security release) is current. Since 8.0 it is licensed under RSALv2, SSPLv1 or AGPLv3, and Search/JSON/TimeSeries/Bloom are built in. node-redis 6 and ioredis 6 default to RESP3 and need Node 20+.
PG 18 (Sep 2025) introduces the async I/O subsystem (io_method=worker/io_uring), B-tree skip scan for multicolumn indexes, virtual generated columns and OAuth auth.
TypeORM 1.0.0 shipped 2026-05-19 (current 1.1.1, 2026-09-01). It requires Node 20+, removes Connection and all global helpers, drops string-based find options, sqlite3 and mysql drivers, and now throws on null/undefined where values. A codemod exists.
MySQL 8.0 reached EOL in April 2026 (8.0.46). LTS lines are 8.4 (8.4.12) and 9.7 (9.7.3). Innovation releases now use calendar versions YY.M.P, starting with 26.7.0 on 2026-07-28. LTS upgrades go 8.4 to 9.7 and cannot skip an LTS.
ClickHouse ships monthly (YY.M versioning): 26.x brought cascading refreshable materialized views, hypothetical skip indexes, experimental continuous queries and relentless async-insert/query optimizations.
Redis 8 folds Search/JSON/TimeSeries/Bloom into core under AGPL, adds Vector Sets for AI workloads, and deprecates the standalone Stack distribution.
Three viable models: shared tables + tenant column (+ Postgres RLS for enforcement), schema-per-tenant (dozens of tenants), database-per-tenant (regulated, few). Enforcement belongs in the data layer, not app code discipline.
SQLite 3.53 (2026) added the Query Result Formatter (QRF) for human-readable fixed-width results and continued steady hardening — the default embedded DB for agents, CLIs and edge runtimes.
Oracle's MySQL switched to innovation releases + LTS: 9.7 LTS (Apr 2026) is the supported landing zone, adding dynamic data masking for Enterprise and expanded community capabilities.
Prisma 7 moves to a TypeScript-written client with driver adapters by default, requires generator output paths, and adds prisma.config.ts. Early 7.0 was rough — 7.10+ settled.
Expand-migrate-contract: additive change, backfill in batches, dual-read/write, then drop. Never a breaking DDL in one deploy. Lock-time budgets (lock_timeout) and tested rollback for every step.
MongoDB 8.0 (late 2024) is a performance-and-ops release: improved sharding and time-series, aggressive default compression, Queryable Encryption GA and expanded operators.
Elasticsearch 9.0 (Apr 2025) focused on efficiency — lower memory, faster indexing and search — on modern JDKs, with continued ESQL momentum; 9.x matured through 2026.