Get more than a cache back! The Microsoft Azure (Redis) Cache Maarten

Abstract Get more than a cache back! The Microsoft Azure (Redis) Cache The Microsoft Azure Redis Cache must be the fourth or fifth generation of a hosted cache service on Azure. This time, an open-source solution has been embraced: Redis. In this session, we’ll see that it’s more than just an in-memory cache system we can use in our applications. Let’s explore what Redis is, what the different data types are and why we should care. And once we grasp how Redis stores its stuff, we’ll delve into how we can use it to its fullest extent: searching the key-value store, transactions, pub/sub support and scripting.

Who am I? Maarten Balliauw Antwerp, Belgium Software Engineer, Microsoft Founder, MyGet AZUG Focus on web ASP.NET MVC, Azure, SignalR,... Former MVP Azure & ASPInsider Big passion: Azure Shameless self promotion: Pro NuGet -

Agenda Azure Cache Redis Data types Transactions Pub/sub Scripting Sharding/partitioning Patterns

Azure Cache

Caching on Azure Windows Server: AppFabric (“Velocity”) ( ) Azure (ASP.NET cache) “Shared Cache” (AppFabric cache, multi-tenant) Self-Hosted Dedicated Cache Managed Cache (the above, but managed by Microsoft and with an SLA) A bit of history...

Caching on Azure 1920: Cache used to be a cache 2012: Cache became the go-to datastore Twitter stores 800 tweets / timeline in Redis New application types on Azure: PHP, Node, Java,... Too much work to write AppFabric clients for all! Way easier: just make it work on Windows and Azure New ways to develop applications

Redis

“Redis is an open source, BSD licensed, networked, single-threaded, in-memory key-value cache and store. It is often referred to as a data structure server since keys can contain strings, hashes, lists, sets, sorted sets, bitmaps and hyperloglogs. ”strings hasheslistssetssorted setsbitmapshyperloglogs

Redis Key-value cache and store (value can be a couple of things) In-memory (no persistence, but you can) Single-threaded (atomic operations & transactions) Networked (it’s a server and it does master/slave) Some other stuff (scripting, pub/sub, Sentinel, snapshot, …) Things to remember

So no persistence? Possible using a lot of I/O AOF (append-only files) RDB (Redis DB snapshots) With or without: all your data must fit in memory

Redis 101 demo

The Little Redis Book By Karl Seguin

Data types TypeExample KeyExample value Stringcache:/home Home page Hashcategories:1Field name description numproducts Member Books Books for sale Setcategories:1:products Listproducts:20:comments[0] -> “...” [1] -> “...” [2] -> “...” Sorted setproducts:bestsellersField Eye Patch Parrot Score Bitmap, Hyperloglog

Data types demo

Data types TypeExample KeyExample value Stringcache:/home user:nextid Home page 2 Hashuser:1Field name handle Member Setuser:1:followers Listuser:1:timeline[0] -> “...” [1] -> “...” [2] -> “...” Sorted settrending:se:tagsField #sdc #redis Score Bitmap, Hyperloglog

Keys Good practice: use a pattern for keys E.g. users:1:maarten Get by id: KEYS users:1:* GET Get by name: KEYS users:*:maarten GET O(N) operation – use with caution! (SCAN)

But....NET? Lots of options! NuGet: ServiceStack.Redis StackExchange.Redis RedisAspNetProviders

Connecting to Redis from.NET demo

But... Azure? “It’s just Redis!” Main differences: auth mechanism and SSL support Use local for development from GitHub or NuGet (Redis-32 or Redis-64)

Azure Redis Cache demo

Azure Redis Cache Redis + Auth + SSL Monitoring Alerts Awesome tool:

Transactions MULTI, EXEC, DISCARD, WATCH No rollbacks (just discard queue) Failures are because of you, not Redis Optimistic locking with WATCH Only execute transaction queue if watched keys did not change

Transactions demo

Pub/Sub (P)SUBSCRIBE, UNSUBSCRIBE, PUBLISH Subscribe to a queue SUBSCRIBE news (or PSUBSCRIBE news:*) Send data to a queue PUBLISH news “This just in!” (optional) Keyspace notifications CONFIG SET notify-keyspace-events KEA PSUBSCRIBE '__key*__:*' (or

Pub/Sub demo

Scripting Run Lua scripts on Redis EVAL ‘return “Hello, World!”’ 0 Scripts are cached (SCRIPT FLUSH) Scripts can be used as functions Although we must pass the body all the time (or use SCRIPT LOAD + EVALSHA) Helper functions available! Base, table, string, math, debug, struct, cjson, cmsgpack, redis.sha1hex

Scripting demo

What if I need more memory? Sharding! On client (consistent hashing) On server (Redis Cluster, not on Azure) Using a proxy (Twemproxy - var options = new ConfigurationOptions { EndPoints = { "my-server" }, Proxy = Proxy.Twemproxy };

Patterns

When can I use Redis? ASP.NET Output Caching (RedisAspNetProviders) ASP.NET Session State General-purpose cache Table Storage secondary index “Cache with benefits” Pub/sub Generally: when use case maps and data fits in RAM

When should I avoid Redis? More data than can fit in RAM Can use multiple, but even then: SUM(RAM) == max. data size Data and query model fits well in a relational model Materialize certain queries in Redis if needed Avoid Redis for large objects Especially with lots of concurrent read/write operations

Counting stuff How would you count “likes” if you were Facebook? Table Storage 1 entity per likeable entity + per server instance for writes, sum entities for read I/O and CPU time... SQL UPDATE... Locking... Redis INCR post:12345 (Every once in a while, check keys to persist)

Counting stuff (2) How would you count “likes” if you were Facebook? And how would you get the 5 most popular posts? Use a sorted set Elements are scored (= # of likes) We can use ZREVRANGE to get the top X posts ZREVRANGE posts:likes 0 5 withscores

Get the latest 5 product reviews No need to go to the database Use a Redis List, truncated at 5 items Need more? Query the database

Rate limiting API should only allows 5 requests per 60 seconds Redis List Record 5 latest requests If we’re at 5, check the leftmost item versus current time :20:2512:20:2212:20:2112:20:1812:19:50

What’sUp? Sending short messages between parties, how to implement? Pub/Sub: Every user gets a subscription, others can end to that subscription Server listens on all subscriptions to archive/persist messages When user comes online, server can publish messages since last visit from archive/a Redis list

Autocompletion How to provide autocompletion over our million- records product catalog? SQL “LIKE” Lucene.NET / ElasticSearch Redis Sorted Set

Intersecting collections “Which friends do we have in common?” Algorithm could be: Find friends that we have in common Find friends they have in common Score the # of connections

Sort We have a series of bugs Priority, Status, Title,... A user follows a few of these bugs How to store? How to query? (give me my top 5 bugs by priority)

Conclusion

Azure Cache Redis is not just a cache Data types Transactions Pub/sub Scripting Sharding/partitioning Patterns 1 thing to remember:

Thank you!