Zero 1.9

Query Correctness and Reliability

Installation

Copynpm install @rocicorp/zero@1.9

Overview

Zero 1.9 improves query/mutation correctness and contains numerous reliability improvements.

Features

• zero_sync_e2e_serving_lag measures completed replicated work from the upstream transaction commit through view-syncer poke. zero_replication_upstream_clock_skew tries to identify measurements biased by clock differences. (#6312)

Performance

Cold Mutation Latency

Before running mutations, Zero Server fetches and caches PostgreSQL schema metadata. This is now 2.7x faster in Zero 1.9 (done in #6292, thanks @diegopereira99!). This is most noticeable with cold-starts in serverless environments like AWS Lambda.

Fixes

• Restores now use Litestream 0.5.15 for legacy-format compatibility, retry transient failures, clean up temporary databases and staged WAL files after failed or interrupted attempts, and retain the previous snapshot generation during active restores.
• insert now succeeds without changing the row when its Zero primary key already exists; before 1.9, the server returned an error.
• Ordered queries now return correct results when cursor fields contain NULL. (thanks @YevheniiKotyrlo!)
• Rebuilt queries now deliver changed rows instead of occasionally leaving clients with stale results.
• Queries no longer drop rows or emit invalid SQL when given an inapplicable scalar hint, and scalar NOT EXISTS now handles empty or NULL results.
• Schema construction, CRUD mutators, and materialized views now preserve a key named __proto__ as user data. (thanks @tjenkinson!)
• SQLite statement caches now retain at most 1,000 idle entries each.
• Terminated client groups now release custom-query timers and caches.
• Large replica transactions can spill dirty pages to WAL instead of retaining the complete write set in native memory.
• Missing replication-lag reports are retried and total_lag no longer grows when reports stop arriving, while serving-lag metrics exclude disconnected or not-yet-validated client groups.
• zero-cache now recovers from half-open PostgreSQL sockets, including over TLS, and the official image applies the bundled postgres.js disconnect patch.
• With PostgreSQL wal_sender_timeout=0, replication no longer enters a continuous reconnect loop. See WAL Sender Timeout.
• Client connection attempts now time out across setup and the server handshake, abandon late sockets, and retry normally.
• Reconnect confirmations no longer produce false slow-query warnings or inflated materialization metrics.
• Different integration versions in a pnpm workspace no longer create peer-qualified duplicate copies of @rocicorp/zero, fixing cross-package type and module-augmentation failures.
• Replicated PostgreSQL type and nullability changes now preserve compound-index column order in SQLite replicas. To repair an affected replica, resync it from Postgres or recreate the PostgreSQL index.
• Expected schema and replica resets now log warnings instead of errors, and zero-cache skips Litestream restore when backups are not configured. (thanks @asterikx!)
• Server CRUD updates and upserts no longer assign primary-key columns, avoiding PostgreSQL locks that could block concurrent foreign-key inserts. (thanks @shayonj!)
• Mutation and query API calls now retry all 5xx responses using the existing four-attempt limit and backoff; 4xx responses still fail without retry. (thanks @shayonj!)
• SQLite corruption failures now log diagnostics, delete the corrupted replica before exit, and support extended corruption errors, with deeper checks available as an opt-in.
• Oversized replication updates now identify the transaction, affected column, and value type without logging the value.
• Fatal replica-writer failures now surface as replication errors and cause zero-cache to exit with a failure instead of silently stopping replication.
• Replication now recovers from upstream disconnects or stalled PostgreSQL writes while flow control is blocked.
• Mutations from multiple tabs in the same client group are no longer skipped or sent out of order.