1. The Redis
Wondering what’s redis? is it a red thing? can we
eat that? Well, so much for questions, let’s start diggin
what redis really is.
" Redis is an open source, BSD licensed, advanced key-value
store. It is often referred to as a data structure server since
keys can contain strings, hashes, lists, sets and sorted sets. ”
Fore more info : http://redis.io/topics/introduction
The Installation
We need to install the service of course to make it work. Jerome (PHP) already prepared
the documentation on how to install redis in your mac. Thanks to Jerome!
Installing on mac : http://goo.gl/000DmC
Installing on ubuntu : http://goo.gl/utn659
NOTE :
“The Redis project does not directly support Windows, however the Microsoft Open Tech group develops and
maintains an experimental Windows port targeting Win32/64”
Working on Redis
After the installation, of course we need to use and work on it. So let’s get started!
● Starting the redis-server
○ in the terminal/command line execute redis-server.
● Executing commands (SET, GET, etc..)
○ in the terminal/command line execute redis-cli and you will be prompted to
enter some redis commands.
DID YOU KNOW?
Redis means “REmote DIctionary Server”

2. Redis Data Types and Basic Commands
Strings
● The most basic kind of Redis value.
● Binary safe (http://en.wikipedia.org/wiki/Binary-safe)
● Can be at max 512MB in length.
Basic Commands ( for more string commands : http://redis.io/commands/#string )
●
SET key value
- Set the string value of a key.
- If the key already exists, the value will be overwritten.
Return : Status code “OK”
●
GET key
- Get the value of a key
- Will return an error if the value of the key is not a string.
- if the key does not exist it will return (nil) or null.
Return : Value of the key
Example : (for GET and SET)
●
redis>
SET
foo
“bar”
OK
redis>
GET
foo
“bar”
APPEND key append_string
- Append a value to a key.
- If the key does not exist, the key will be created with the value of the string to
append.
Return : Length of the value of the key.
Example :
redis>
SET
foo
“Hello”
OK
redis>
APPEND
foo
“
World”
(integer)
11
redis>
GET
foo
“Hello
World”

3. ●
INCR key
- Increment the integer value of a key by one.
- Will return an error if the value is not an integer
- If key does not exist, initial value will be 0 then perform increment.
Return : The value of the key after the increment
Example :
●
redis>
SET
foo
10
OK
redis>
INCR
foo
(integer)
11
redis>
GET
foo
11
INCRBY key increment
- Increment the integer value of a key by the given number.
- Will return an error if the value is not an integer.
- If key does not exist, initial value will be 0 then perform decrement.
Return : The value of the key after the increment
Example :
●
redis>
SET
foo
10
OK
redis>
INCRBY
foo
10
(integer)
20
redis>
GET
foo
20
DECR key
- Decrement the integer value of a key by one.
- Will return an error if the value is not an integer
- If key does not exist, initial value will be 0 then perform decrement.
Return : The value of the key after the decrement
Example :
redis>
SET
foo
10
OK
redis>
DECR
foo
(integer)
9
redis>
GET
foo
9

4. ●
DECRBY key decrement
- Decrement the integer value of a key by the given number.
- Will return an error if the value is not an integer.
- If key does not exist, initial value will be 0 then perform decrement.
Return : The value of the key after the decrement
Example :
●
redis>
SET
foo
10
OK
redis>
DECRBY
foo
9
(integer)
1
redis>
GET
foo
1
STRLEN key
- Returns the length of value stored in a key
Return : length of the value, 0 if key does not exist
Example :
redis>
SET
foo
“I
am
legend.”
OK
redis>
STRLEN
foo
(integer)
12
Lists
● List of strings sorted by insertion order
● Can append or prepend in a list
Basic Commands ( for more list commands : http://redis.io/commands#list )
●
{L,R}PUSH(X) key value [value…]
- Prepend/Append multiple values to a list. (LPUSH prepend, RPUSH append)
- If key does not exist, it will create an empty list then execute the push process.
- {L,R}PUSHX appends/prepends only if the list exists.
Return : length of the list after the push process
Example :
redis>
RPUSH
todo_list
“Clean
house”
“Workout”
(integer)
2

5.
redis>
LRANGE
todo_list
0
-­‐1
1)
“Clean
House”
2)
“Workout”
redis>
LPUSH
todo_list
“Clean
house”
“Workout”
(integer)
2
redis>
LRANGE
todo_list
0
-­‐1
1)
“Workout”
2)
“Clean
House”
DID YOU KNOW?
To display all elements of the list, execute LRANGE key 0 -1
●
LINDEX key index
- Prepend/Append multiple values to a list. (LPUSH prepend, RPUSH append)
- If key does not exist, it will create an empty list then execute the push process.
Return : length of the list after the push process
Example :
redis>
LPUSH
foo
“bar”
“fizz”
“bazz”
(integer)
3
redis>
LINDEX
foo
0
“bar”
redis>
LINDEX
foo
1
“fizz”
redis>
LINDEX
foo
2
“bazz”
redis>
LINDEX
foo
3
(nil)
● LRANGE
key start end
- Get a range of elements from a list
Return : Elements within the range specified
Example :
redis>
LPUSH
foo
“bar”
“fizz”
“bazz”
(integer)
3
redis>
LRANGE
foo
0
1
1)
“bazz”
2)
“fizz”

6.
Sets
● Unordered collection of strings.
Basic Commands ( for more string commands : http://redis.io/commands#set )
● SADD key member [ member… ]
- Add specified member to a set
- if key doesn’t exist, new set will be created and then add the specified keys.
- Existing member will be ignored.
- Will return an error if the value stored in the key is not a set.
Return : The number of members/elements that were added to the set.
Example :
redis>
SADD
foo
“bar”
“fizz”
“fizz”
(integer)
2
redis>
SMEMBERS
foo
1)
“bazz”
2)
“fizz”
● SMEMBERS key
- Get all the members in a set
- if key does not exist, empty set will be returned.
Return : All members of a set
Example :
redis>
SADD
foo
“bar”
“fizz”
“fizz”
(integer)
2
redis>
SMEMBERS
foo
1)
“bazz”
2)
“fizz”
● SCARD key
- Get the number of elements in a set
Return : The number of elements in the set. 0 if key does not exist.
Example :
redis>
SADD
foo
“bar”
“fizz”
“fizz”
(integer)
2
redis>
SADD
foo
“bazz”

7.
(integer)
1
redis>
SCARD
foo
(integer)
3
● SISMEMBER key member
- Check if a member is a member of the set stored in specified key .
Return : 1 if member exist, 0 if not
Example :
redis>
SADD
foo
“bar”
(integer)
1
redis>
SISMEMBER
foo
“bar”
(integer)
1
redis>
SISMEMBER
foo
“test”
(integer)
0
● SDIFF key [ key… ]
- Differentiate the first key to the other specified key
Return : The members of the first set not existing on the specified set/s.
Example :
redis>
SADD
foo
“bar”
(integer)
1
redis>
SADD
foo
“test”
(integer)
1
redis>
SADD
foo2
“bar”
(integer)
1
redis>
SADD
foo2
“fizz”
(integer)
1
redis>
SDIFF
foo
foo2
1)
“test”
Hashes
● maps between string fields and string values.
● perfect for data type to represent objects (like a user with id, name, username, password, etc).
Basic Commands ( for more string commands : http://redis.io/commands#hash )
●
HSET key field value
- Set a field in hash stored at key.
- If field already exist, value of the field will be overwritten.

8. Return : 1 if field is new and value was set, 0 if field exists and value was
overwritten.
Example :
●
redis>
HSET
hashtest
hashfield
“hashvalue”
(integer)
1
redis>
HSET
hashtest
hashfield
“hashvalueoverwrite”
(integer)
0
HMSET key field value [field value…]
- Set multiple field in hash stored at key.
- If fields already exist, value of the field will be overwritten.
Return : OK if no error in setting the key
Example :
●
redis>
HMSET
hashtest
field1
“hashval1”
field2
“hashval2”
OK
redis>
HGET
hashtest
field1
“hashval1”
redis>
HGET
hashtest
field2
“hashval2”
redis>
HMSET
hashtest
field1
“hashvaloverwrite1”
OK
redis>
HGET
hashtest
field1
“hashvaloverwrite1”
HGET key field
- Returns the value of the specified field.
Return : Value of the field. If field does not exist nil will be returned.
Example :
●
redis>
HSET
hashtest
field1
“hashval1”
OK
redis>
HGET
hashtest
field1
“hashval1”
HMGET key field [field…]
- Returns the value of the specified field/s.

9. Return : List of values associated with the field/s specified.
Example :
●
redis>
HMSET
hashtest
field1
“hashval1”
field2
“hashval2”
OK
redis>
HGET
hashtest
field1
field2
field3
1)
“hashval1”
2)
“hashval2”
3)
(nil)
HDEL key field [field…]
- Removes the specified field/s from the hash
Return : Number of fields that were removed.
Example :
redis>
HSET
hashkey
field1
“hashval1”
OK
redis>
HDEL
hashkey
field0
(integer)
0
redis>
HDEL
hashkey
field1
(integer)
1
Sorted Sets
● almost similar to SETS. (collection of strings)
● associated with scores that will be used in ordering the set.
● members are unique, scores can be repeated.
● in games, this is often used for computing ranks.
Basic Commands ( for more string commands : http://redis.io/commands#sorted_set )
●
ZADD key score member [score member...]
- Adds a member with specific score in the sorted set.
- If a specified member is existing, score will be overwritten.
Return : Number of elements added in the sorted set not including the existing
member value update.
Example :
redis>
ZADD
sstest
1
“ssmember1”
(integer)
1
redis>
ZADD
sstest
2
“ssmember2”
(integer)
1
redis>
ZADD
sstest
3
“ssmember3”

10.
●
(integer)
1
redis>
ZRANGE
sstest
0
-­‐1
WITHSCORES
1)
“ssmember1”
2)
“1”
3)
“ssmember2”
4)
“2”
5)
“ssmember3”
6)
“3”
ZREM key member [member...]
- Removes specified member/s in a sorted set.
- If a specified member is existing, score will be overwritten.
Return : Number of members removed from the sorted set.
Example :
●
redis>
ZADD
sstest
1
“ssmember1”
(integer)
1
redis>
ZADD
sstest
2
“ssmember2”
(integer)
1
redis>
ZREM
sstest
“ssmember2”
(integer)
1
redis>
ZRANGE
sstest
0
-­‐1
WITHSCORES
1)
“ssmember1”
2)
“1”
ZRANGE key start stop [WITHSCORES]
- Returns elements within the specified range. (elements are in ascending order,
use ZREVRANGE to make the order in descending)
- start and stop option are both zero-based indexes, 0 is the first element,
1 is next and so on.
- WITHSCORES option will also return the element with the score.
Return : List of elements based on the range specified.
Example :
redis>
ZADD
sstest
1
“ssmember1”
(integer)
1
redis>
ZADD
sstest
2
“ssmember2”
(integer)
1
redis>
ZADD
sstest
3
“ssmember3”
(integer)
1
redis>
ZRANGE
sstest
0
1
1)
“ssmember1”
2)
“ssmember2”

11. Redis Configuration
Redis can be started without any configuration file. It will use the default configuration of
redis. Easy right? But using default configuration is recommended only for testing and
development phase of your application.
3 Ways to configure redis server
1. Using a configuration file
●
create a redis.conf file containing your configurations (see this link for redis configurations
directives -> https://raw.github.com/antirez/redis/2.6/redis.conf)
●
start redis server with the config file you made
○
redis-­‐server
/path/to/redis.conf
2. Passing arguments in the command line
●
arguments passed are the same with the directives in redis.conf file. You just have to add
the prefix --.
○
●
redis-­‐server
-­‐-­‐daemonize
yes
-­‐-­‐port
6380
this will generate an in-memory configuration file.
3. On the fly
●
While the redis-server is running you can execute a command in redis-cli
○
CONFIG
SET
timeout
0
●
●
arguments passed to CONFIG SET are also the same in the config file directives.
note that setting configuration on the fly will not affect the redis.conf file you made.