aj07mm

What happened to my data in Redis?

This post is a FAQ for Redis, when users don’t see the data they stored in Redis.

As per the Redis project, Redis is described as an in-memory data structure store. If you are using Redis as an LRU cache, you can see following recommendation from the Redis docs: Using Redis as an LRU cache

Lately, I have received multiple questions about when Redis will lose data. This data loss can be as simple as a few keys disappearing unexpectedly or complete loss of all data in Redis. Below I will talk about the most common causes as well as a few rare cases where this can happen.

Note: These scenarios are common to all Redis hosting environments, including self-hosting Redis in your own data center.

aj07mm

(ns testing.core)

(def start (atom 0)) ; Record start time.

(def c1 (ref 0)) ; Counter 1
(def c2 (ref 0)) ; Counter 2
(def c3 (ref 0)) ; Counter 3

(defn milliTime 
  "Get current time in millisecond."

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(defn sleep-print-update
  [sleep-time thread-name update-fn]
  (fn [state]
    (Thread/sleep sleep-time)
    (println (str thread-name ": " state))
    (update-fn state)))
(def counter (ref 0))
; -------------
(future (dosync (commute counter (sleep-print-update 100 "Thread A" inc))))
;Thread A: 0

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(defmacro print-1
  [expr]
  (let [result expr]
    (println result)
    result))

(defmacro print-2
  [expr]
  (list 'let ['result expr]
    (list 'println 'result)

aj07mm

Connecting to the Memory database This will mostly be a straight translation of the tutorial code, with comments where things aren't obvious.

;; Import the Datomic Peer library (usable as 'Peer' from here on) (import datomic.Peer)

;; Create the in memory database, calling the static class method Peer#createDatabase (def uri "datomic:mem://hello") (Peer/createDatabase uri)

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import unittest
import re
from collections import defaultdict

"""
The phone matchup coding test.

A phone company keeps record of all calls that have been successfully
established. For these calls, the company registers
whether they fail mid-call or complete successfully. We are interested in

aj07mm

Table of Contents generated with DocToc

• Using GPG
  • What is it?
  • Installing GPG
    • Linux
      • Debian based distributions
• Fedora based distributions

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__author__ = 'ekowibowo'
import json
import os
import redis

REDIS_HOST = os.getenv('SS_ABTEST_REDIS_HOST', '192.168.59.103')
r = redis.StrictRedis(host=REDIS_HOST)

for k in r.keys('abtest:experiments:*'):
    r.delete(k)

aj07mm

The following has been tested to work on an `emacs -Q` session:

1. Launch `emacs -Q`
2. Add the below in the scratch buffer:

<!-- language: lang-el -->

    (require 'package)
    (add-to-list 'package-archives
                 '("melpa" . "http://melpa.org/packages/") t)

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from django.db import models

class Post(models.Model):

    def generate_slug(self):
        return self.name + 'asdasdasdasd123'

    name = models.CharField(max_length=255)
    description = models.TextField()
    attachment = models.FileField()