Mixer: All content tagged as Mixer in NoSQL databases and polyglot persistence
Friday, 23 September 2011
Memcached and Sherpa for Yahoo! News Activity Data Service
Mixer, the recently announced Yahoo’s new data service for news activities, uses Memcached and Sherpa for its data backend. Plus a combination of asynchronous libraries and task execution tools:
The data processing model and the clear separation between read and write data solutions is not only compelling, but essential for maintaining the SLA (max. 250ms/response):
Memcache maintains two types of materialized views: 1) Consumer-pivoted, and 2) Producer-pivoted. Consumer-pivoted views (e.g. user’s friends’ latest read activity) are refreshed at query time by refresh tasks. Producer-pivoted views (e.g. user’s latest read activity) are refreshed at update time (i.e. when “read” event is posted). And producer-pivoted views are used to refresh consumer-pivoted views.
Sherpa is Yahoo!’s cloud-based NoSql data store that provides low-latency reads and writes of key-value records and short range scans. Efficient range scans are particular important for the Mixer use cases. The “read” event is stored in the Updates table. The Updates table is a Sherpa Distributed Ordered Table that is ordered by “user,timestamp desc”. This provides efficient scans through a user’s latest read activity. A reference to the “read” record is stored in the UpdatesIndex table to support efficient point lookups. UpdatesIndex is a Sherpa Distributed Hash Table
Original title and link: Memcached and Sherpa for Yahoo! News Activity Data Service (©myNoSQL)
