Azure: checks and maintenance

Do the Azure setup first.

Scheduled checks on recent data

The check function runs every 5 minutes. It asks two questions of the table and posts to a webhook when either has an answer:

• Which pumps averaged above 80° over the last 10 minutes? A SQL query over recent data. The time filter skips every file whose time range lies outside the window, before any data is read.
• Which pumps have sent nothing for 15 minutes? lake.latest() answers from the last-value index, without scanning the table.

Point it at any URL that takes a JSON POST, such as a Slack incoming webhook (which reads the text field) or a Logic App with an HTTP trigger that sends email:

az functionapp config appsettings set -g $RG -n $APP --settings ALERT_WEBHOOK=https://hooks.slack.com/services/…

Change the SQL to check anything the table holds: a rate of change, a counter that stopped increasing, readings outside a band per site (join a devices table). Over longer windows, a rollup keeps the query small. A check that also wants a record of what it found can append its findings to another Timelake table.

Maintenance

Each append already merges small files and removes duplicates. The maintain timer runs at the start of every hour: it also sorts each finished day into one file, applies retention, and deletes files no version needs. Remove it from function_app.py if you don't need it.