Redis

Question 1

Azure Cache for Redis tiers

Answer 1

Tier
Basic
Standard
Premium
Enterprise
Enterprise Flash

Question 2

Basic

Answer 2

An OSS Redis cache running on a single virtual machine (VM). This tier has no service-level agreement (SLA) and is ideal for development/test and noncritical workloads.

Question 3

Standard

Answer 3

An OSS Redis cache running on two VMs in a replicated configuration.

Question 4

Premium

Answer 4

High-performance OSS Redis caches. This tier offers higher throughput, lower latency, better availability, and more features. Premium caches are deployed on more powerful VMs compared to the VMs for Basic or Standard caches.

Question 5

Enterprise

Answer 5

High-performance caches powered by Redis Labs’ Redis Enterprise software. This tier supports Redis modules including RediSearch, RedisBloom, and RedisTimeSeries. Also, it offers even higher availability than the Premium tier.

Question 6

Enterprise Flash

Answer 6

Cost-effective large caches powered by Redis Labs’ Redis Enterprise software. This tier extends Redis data storage to nonvolatile memory, which is cheaper than DRAM, on a VM. It reduces the overall per-GB memory cost.

Question 7

Redis cache Name

Answer 7

The Redis cache needs a globally unique name. The name has to be unique within Azure because it’s used to generate a public-facing URL to connect and communicate with the service.

The name must be between 1 and 63 characters, composed of numbers, letters, and the ‘-‘ character. The cache name can’t start or end with the ‘-‘ character, and consecutive ‘-‘ characters aren’t valid.

Question 8

Cache type

Answer 8

The tier determines the size, performance, and features that are available for the cache.

Question 9

Clustering support

Answer 9

With the Premium, Enterprise, and Enterprise Flash tiers you can implement clustering to automatically split your dataset among multiple nodes. To implement clustering, you specify the number of shards to a maximum of 10. The cost incurred is the cost of the original node, multiplied by the number of shards.

Question 10

Accessing the Redis instance

Answer 10

ping Ping the server. Returns PONG.

set [key] [value] Sets a key/value in the cache. Returns “OK” on success.

get [key] Gets a value from the cache.

exists [key] Returns ‘1’ if the key exists in the cache, ‘0’ if it doesn’t.

type [key] Returns the type associated to the value for the given key.

incr [key] Increment the given value associated with key by ‘1’. The value must be an integer or double value. This returns the new value.

incrby [key] [amount] Increment the given value associated with key by the specified amount. The value must be an integer or double value. Returns the new value.

del [key] Deletes the value associated with the key.

flushdb Delete all keys and values in the database.

Question 11

Adding an expiration time to values

Answer 11

expire counter 5

Question 12

Connecting to your Redis cache with StackExchange.Redis

Answer 12

[cache-name].redis.cache.windows.net:6380,password=[password-here],ssl=True,abortConnect=False

Question 13

Creating a connection

Answer 13

You create a ConnectionMultiplexer instance using the static ConnectionMultiplexer.Connect or ConnectionMultiplexer.ConnectAsync method, passing in either a connection string or a ConfigurationOptions object.

using StackExchange.Redis;
…
var connectionString = “[cache-name].redis.cache.windows.net:6380,password=[password-here],ssl=True,abortConnect=False”;
var redisConnection = ConnectionMultiplexer.Connect(connectionString);

Question 14

Accessing a Redis database

Answer 14

The IDatabase type represents the Redis database. You can retrieve one using the GetDatabase() method:

IDatabase db = redisConnection.GetDatabase();

Question 15

example of storing/getting a key/value in the cache:

Answer 15

bool wasSet = db.StringSet(“favorite:flavor”, “i-love-rocky-road”);

string value = db.StringGet(“favorite:flavor”);
Console.WriteLine(value); // displays: ““i-love-rocky-road””

Question 16

Executing other commands

Answer 16

The IDatabase object has an Execute and ExecuteAsync method that can be used to pass textual commands to the Redis server. For example:

var result = db.Execute(“ping”);
Console.WriteLine(result.ToString()); // displays: “PONG”

Question 17

Create an Azure Cache for Redis instance

Answer 17

Create an Azure Cache for Redis instance by using the az redis create command.

redisName=az204redis$RANDOM
az redis create –location <myLocation> \
--resource-group az204-redis-rg \
--name $redisName \
--sku Basic --vm-size c0</myLocation>