get more than a cache back! the microsoft azure redis cache (ndc oslo)
TRANSCRIPT
Get more than a cache back!The Microsoft Azure (Redis) CacheMaarten Balliauw@maartenballiauw
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 http://blog.maartenballiauw.be @maartenballiauw Shameless self promotion: Pro NuGet - http://amzn.to/pronuget2
Agenda
Azure Cache Redis Data types Transactions Pub/sub Scripting Sharding/partitioning
Patterns
Azure Cache
Caching on Azure
Windows Server: AppFabric (“Velocity”) (2009-2010) 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! http://www.redis.io/clients Way easier: just make it work on Windows and Azure
New ways to develop applications
Redis
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.”
REmote DIctionary Server
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 101demo
The Little Redis Book
http://openmymind.net/redis.pdf
By Karl Seguin
Data types
Type Example Key Example value
String cache:/home <html><head><title>Home page</title>
Hash categories:1 Fieldnamedescriptionnumproducts
MemberBooksBooks for sale50000
Set categories:1:products 20 11 56 89 32 4
List products:20:comments [0] -> “...”[1] -> “...”[2] -> “...”
Sorted set products:bestsellers FieldEye PatchParrot
Score8463282120
+ Bitmap, Hyperloglog
Data typesdemo
Data types
Type Example Key Example value
String cache:/homeuser:nextid
<html><head><title>Home page</title>2
Hash user:1 Fieldnamehandle
MemberMaarten@maartenballiauw
Set user:1:followers 10 42 99 85
List user:1:timeline [0] -> { ... }[1] -> { ... }[2] -> { ... }
Sorted set trending:no:tags Field#ndcoslo#redis
Score8463282120
+ 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!
But... .NET?
Lots of options! http://www.redis.io/clients NuGet: ServiceStack.Redis StackExchange.Redis RedisAspNetProviders ...
Connecting to Redis from .NETdemo
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 Cachedemo
Azure Redis Cache
Redis + Auth + SSL Monitoring Alerts Awesome tool: www.redsmin.com
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
Transactionsdemo
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 notificationshttp://www.redis.io/topics/notifications
CONFIG SET notify-keyspace-events KEA PSUBSCRIBE '__key*__:*' (or __keyspace@0__:foo)
Pub/Subdemo
Scripting
Run Lua scripts on Redishttp://www.redis.io/commands/eval
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
Scriptingdemo
What if I need more memory?
Sharding! On client (consistent hashing) On server (Redis Cluster, not on Azure) Using a proxy (Twemproxy - https://
github.com/twitter/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... ...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
1 2 3 4 5
12:20:25 12:20:22 12:20:21 12:20:18 12:19:50
What’sUp?
Sending short messages between parties, how to implement? Pub/Sub: Every user gets a subscription, others can send 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 bugsPriority, Status, Title, ...
A user follows a few of these bugsHow to store?How to query? (give me my top 5 bugs by priority)
Conclusion
Conclusion
Azure Cache Redis is not just a cache Data types Transactions Pub/sub Scripting Sharding/partitioning
Patterns 1 thing to remember: http://openmymind.net/redis.pdf
Thank you!http://blog.maartenballiauw.be@maartenballiauwhttp://amzn.to/pronuget2