seiflotfy

Set 1	HLL 1	Set 2	HLL 2	S1 ∪ S2	HLL1 ∪ HLL2	S1 ∩ S2	HLL1 ∩ HLL2
6987812	6997888	6962294	6951998	8550732	8553641	5399374 (63.000000%)	5398755 (63.116455%)
7141370	7158982	3678358	3684955	8546742	8547740	2272986 (26.000000%)	2314317 (27.075192%)
3124534	3107282	8651079	8604982	10227258	10230622	1548355 (15.000000%)	1506744 (14.727785%)
8850249	8862284	5290225	5308950	9375807	9387095	4764667 (50.000000%)	4781208 (50.933841%)
667001	665795	2030138	2019862	2217972	2209121	479167 (21.000000%)	469897 (21.270768%)
1344715	1355003	5560979	5585400	6788416	6799020	117278 (1.000000%)	122419 (1.800539%)
9527013	9539805	8888494	8904840	13514502	13547342	4901005 (36.000000%)	4923976 (36.346436%)
1336356	1347820	183299	183805	1432428	1439300	87227 (6.000000%)	88551 (6.152

antirez

Meltdown fix impact on Redis performances in virtualized environments

UPDATE: apparently kernel difference may have a serious impact, so I'll redo the test from scratch.

Test performed with AOF enabled, fsync policy 1 second, allowing the rewrites to be triggered.

Command lines used:

antirez

# LVDB - LLOOGG Memory DB
# Copyriht (C) 2009 Salvatore Sanfilippo <antirez@gmail.com>
# All Rights Reserved

# TODO
# - cron with cleanup of timedout clients, automatic dump
# - the dump should use array startsearch to write it line by line
#   and may just use gets to read element by element and load the whole state.
# - 'help','stopserver','saveandstopserver','save','load','reset','keys' commands.
# - ttl with milliseconds resolution 'ttl a 1000'. Check ttl in dump!

dvirsky

# bash completion for redis-cli and redis-server

have redis-server &&
_redisserver()
{
    local cur prev split=false

    COMPREPLY=()
    _get_comp_words_by_ref cur prev

dvirsky

Creating a redis Module in 15 lines of code!

A quick guide to write a very very simple "ECHO" style module to redis and load it. It's not really useful of course, but the idea is to illustrate how little boilerplate it takes.

Step 1: open your favorite editor and write/paste the following code in a file called module.c

#include "redismodule.h"
/* ECHO <string> - Echo back a string sent from the client */
int EchoCommand(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {

itamarhaber

Redis Watch Trivia "Facts"

a Meta Archive

Look for a new #RedisTrivia fact every Thursday with your Redis Watch newsletter :)

Lifted with permission from the Redis Watch Archive: https://redislabs.com/redis-watch-archive

1. Redis stands for REmote DIctionary Server
2. everybody knows that Redis' default port is 6379, but have you ever wondered why? The answer is that 6379 spells MERZ on the phone's keypad (want to know what MERZ is? Read the appendix at http://oldblog.antirez.com/post/redis-as-LRU-cache.html [warning: slightly NSFW links inside])

alexanderscott

-- @desc:   Copy a key without knowing its type
-- @usage:  redis-cli EVAL "$(cat COPY.lua)" 2 <key> <destKey>

local function COPY(key, dest)
  local keyType = redis.call("TYPE", key)

  if keyType == "set" then redis.call("SUNIONSTORE", dest, key)
  elseif keyType == "zset" then redis.call("ZUNIONSTORE", dest, 1, key)
  elseif keyType == "list" then redis.call("SORT", key, "BY", "NOSORT", "STORE", dest)
  elseif keyType == "string" then redis.call("SET", dest, redis.call("GET", key))

antirez

#include <stdio.h>
  #include <stdlib.h>
             int
            main()
           {int h=9,
          d=0,x;while
         (h--){for(x=0;
       x<39;x++){int a=x
     -6;if(a<0)a=-a;printf

tylerneylon

-- Two dashes start a one-line comment.

--[[
     Adding two ['s and ]'s makes it a
     multi-line comment.
--]]

----------------------------------------------------
-- 1. Variables and flow control.
----------------------------------------------------

jboner

Latency Comparison Numbers (~2012)
----------------------------------
L1 cache reference                           0.5 ns
Branch mispredict                            5   ns
L2 cache reference                           7   ns                      14x L1 cache
Mutex lock/unlock                           25   ns
Main memory reference                      100   ns                      20x L2 cache, 200x L1 cache
Compress 1K bytes with Zippy             3,000   ns        3 us
Send 1K bytes over 1 Gbps network       10,000   ns       10 us
Read 4K randomly from SSD*             150,000   ns      150 us          ~1GB/sec SSD