Scheduled upgrade

Write the scheduled-upgrade notice that Lumenrack sends to the owner of a Lumenrack Vault account before a major version upgrade. Cover the facts below.

Lumenrack Vault is the Lumenrack managed analytics database. Every Vault service on the account is being upgraded from 3.x to Vault 4.0, a new major version, during a single maintenance window.

Maintenance window: Tuesday, October 6, 2026, 02:00 to 04:00 UTC. Each service is upgraded once within that window. The exact start time for each region is on the status page. https://lumenrack-email.s3.amazonaws.com/status

Affected services on this account, with their regions:

• events-prod in us-east-1
• metrics-warehouse in eu-west-1

Service names are set in the mono face.

What to expect: each service is upgraded in place with a rolling restart. Open connections are closed once and queries in flight at that moment fail once; the Lumenrack drivers reconnect and retry automatically, so most applications see a pause of under 60 seconds. Data, schemas, and service settings are not changed. No action is required before or after the window. Services stay on 4.0 afterwards; there is no rollback to 3.x. Upgrade guide: https://lumenrack-email.s3.amazonaws.com/docs/vault-upgrades

Notable changes in Vault 4.0, in this order:

1. Token authentication is available in beta. Docs: https://lumenrack-email.s3.amazonaws.com/docs/vault-token-auth
2. Async inserts are on by default for newly created services. Small inserts are batched automatically, which reduces write amplification for high-throughput workloads. Existing services keep their current setting; set async_insert = 0 on a new service to turn it off.
3. Skip indexes work on JSON columns. Bloom filter, token, and ngram index types now apply to JSON columns, so granules that do not contain a queried JSON path are skipped instead of scanned.
4. Column statistics are generally available. Vault now creates minmax and uniq statistics for new columns automatically and builds them during merges, so the query planner can order filters and prune parts.
5. Materialized CTEs. A WITH clause referenced more than once in a query is evaluated once and stored in a temporary table instead of being recomputed.

One backward-incompatible change: the default MySQL type mapping has changed. MySQL DATE columns read through the MySQL integration now map to Date32 instead of Date, which fixes pre-1970 dates. Anyone with a MySQL integration should verify it after the upgrade.

The full release notes are in the changelog, and that link is the one call to action. https://lumenrack-email.s3.amazonaws.com/changelog/vault-4-0

Questions go to Lumenrack support. https://lumenrack-email.s3.amazonaws.com/support

The footer says the message is about the recipient's account, gives the postal address, and links to the console https://lumenrack-email.s3.amazonaws.com/console support https://lumenrack-email.s3.amazonaws.com/support and privacy https://lumenrack-email.s3.amazonaws.com/privacy

Dark mode should be supported.

Use /world/lumenrack-email for brand chrome and CSS; the status family fits. Use the absolute HTTPS URLs from tokens.json; do not use /world/ paths as image src.

Leave the HTML in output/email.html, a plain-text version in output/email.txt, and the subject in output/meta.json as {"subject": "..."}. Don't include From, To, or Date headers.