redis is the answer, what's the question - tech nottingham

Garry Shutler | @gshutler

Garry Shutler | @gshutler

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What is it?

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What is it good for?

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The Redis protocol

Simple to implement

Fast to parse

Human readable

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The Redis protocol

COMMAND KEY ARGS...

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The Redis protocol

redis.command(key, *args)

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The Redis protocol

SET mykey 3

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The Redis protocol

redis.set("mykey", 3)

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The Redis protocol

SET mykey 3 EX 3600

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The Redis protocol

redis.set("mykey", 3, { "ex": 3600 })

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Cache

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Cachefunction cached(key, fn) { var value = redis.get(key); if (!value) { value = fn(); redis.set(key, value); } return value;}

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Cachefunction expensiveThing() { return cached("expensive", function () { // do something that's expensive return expensiveValue; });}

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Cache

expensiveThing(); // missexpensiveThing(); // hitexpensiveThing(); // hit

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Cachefunction expensiveThing(param) { var key = "expensive:" + param; return cached(key, function () { sleep(param); return param; });}

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Cache

expensiveThing(1); // missexpensiveThing(1); // hitexpensiveThing(2); // missexpensiveThing(2); // hitexpensiveThing(1); // hit

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Cachefunction cached(key, expiry, fn) { var value = redis.get(key); if (value) { redis.expire(key, expiry); } else { value = fn(); redis.set(key, value, { "ex": expiry }); } return value;}

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Cachefunction expensiveThing(param) { var key = "expensive:" + param; return cached(key, 3600, function () { sleep(param); return param; });}

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or vs

Relative In 5 minutes

Absolute At 9am

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Expiration

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Expiration

my_report:last_hour

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Expiration

my_report:2015051118

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Data types

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String

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List

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Set

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Conditional GET

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Conditional GETvar etagKey = "etag:" + url;

if (storedEtag = redis.get(etagKey)) { headers["If-None-Match"] = storedEtag;}

var response = http.get(url, headers);var etag = response.headers["ETag"];

redis.set(etagKey, etag, { "ex": 300 });

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Touch values

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Touch values

SET {KEY} 1 EX {TIME}

EXISTS {KEY}

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Ephemeral lookups

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Ephemeral lookups

Forgotten password IDs

OAuth access tokens

Voucher codes

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Time-series counter

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Time-series counter

INCR clicks:201505111830

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Time-series counter

INCR clicks:201505111830INCR clicks:2015051118INCR clicks:20150511

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Time-series counter

INCR clicks:201505111830EXPIRE clicks:201505111830 86400

INCR clicks:2015051118EXPIRE clicks:2015051118 2419200

INCR clicks:20150511

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Time-series counter> MGET clicks:201505111826 clicks:201505111827 clicks:201505111828 clicks:201505111829 clicks:2015051118301)"5"2)(nil)3)"2"4)"10"5)"1"

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Unique visitors

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Unique visitors

SADD {KEY} {VALUE}

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Unique visitors

SADD visitors:2015051118 1SADD visitors:2015051118 2SADD visitors:2015051118 2

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Unique visitors

SCARD {KEY}

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Unique visitors

SCARD visitors:2015051118

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Queuing

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Queuing

RPUSH {KEY} {VALUE}

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Queuing

RPUSH queue 1RPUSH queue 2

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Queuing

["1", "2"]

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Queuing

LPOP {KEY}

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Queuing

LPOP queue

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Queuing

"1"

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Queuing

["2"]

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Queuing

LPUSH queue 3

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Queuing

["3", "2"]

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Queuing

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RPUSH queue 4 RPUSH queue 5

queue

LPOP queue LPOP queue LPOP queue

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Queuing

BLPOP {KEY}... {TIMEOUT}

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Queuing

Encoded values

Reply queues

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Have a go

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Have a go

Cached Fibonacci

Distributed processing

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Garry Shutler | @gshutler