Cosmos DB change feed

In the Ultra Transcenders books

AI-200

Each book explains Cosmos DB change feed in context, with comparison tables and the common traps.

Terms in this definition

• Cosmos DB

  NoSQL database distributed globally, offering writes in multiple regions, automatic indexing and latency below 10 ms.

• Container

  Something that groups data. Blob Storage containers sit inside a storage account and hold blobs much as folders hold files; Cosmos DB containers hold items and set the scope for partitioning and throughput.

• ALL

  A DAX function that ignores any filters and gives back every row of a table or every value of the named columns. Used within CALCULATE, it works as a modifier that clears filters, although REMOVEFILTERS states that intent more clearly where it is available.

• Authorisation levels

  Key requirements for HTTP triggers in Azure Functions: Anonymous needs no key, Function accepts a function or host key, and Admin requires the master key.

• Azure Functions trigger

  Every function is started by exactly one thing. That thing might be a web call over HTTP, a schedule, the arrival of a blob, a message landing in a queue or a change in a database.

• Change feed processor

  Azure Cosmos DB SDK library for consuming change feeds. Its parts are the container being watched, a container holding leases, compute instances with unique names and a delegate; leases are shared out between instances and changes arrive at least once.

Related terms

• Apache Spark pool

  Spark compute in Azure Synapse used to build and update Delta Lake tables, run machine learning and stream changes from the Cosmos DB change feed.

• Lease container

  Holds the lease documents through which the Cosmos DB change feed processor records how far each partition key range has got and shares work out between instances.