Redis transactions allow the execution of a group of commands in a single step. Following are the two properties of Transactions.

• All commands in a transaction are sequentially executed as a single isolated operation. It is not possible that a request issued by another client is served in the middle of the execution of a Redis transaction.

• Redis transaction is also atomic. Atomic means either all of the commands or none are processed.

Sample

Redis transaction is initiated by command MULTI and then you need to pass a list of commands that should be executed in the transaction, after which the entire transaction is executed by EXEC command.

redis 127.0.0.1:6379> MULTI
OK
List of commands here
redis 127.0.0.1:6379> EXEC

Example

Following example explains how Redis transaction can be initiated and executed.

redis 127.0.0.1:6379> MULTI
OK
redis 127.0.0.1:6379> SET tutorial redis
QUEUED
redis 127.0.0.1:6379> GET tutorial
QUEUED
redis 127.0.0.1:6379> INCR visitors
QUEUED
redis 127.0.0.1:6379> EXEC
1) OK
2) "redis"
3) (integer) 1

Redis Transaction Commands

Following table shows some basic commands related to Redis transactions.

Redis keys commands are used for managing keys in Redis. Following is the syntax for using redis keys commands.

Syntax

redis 127.0.0.1:6379> COMMAND KEY_NAME

Example

redis 127.0.0.1:6379> SET tutorialspoint redis
OK
redis 127.0.0.1:6379> DEL tutorialspoint
(integer) 1

In the above example, DEL is the command, while tutorialspoint is the key. If the key is deleted, then the output of the command will be (integer) 1, otherwise it will be (integer) 0.

Redis Keys Commands

Following table lists some basic commands related to keys.

Redis SAVE command is used to create a backup of the current Redis database.

Syntax

Following is the basic syntax of redis SAVE command.

127.0.0.1:6379> SAVE

Example

Following example creates a backup of the current database.

127.0.0.1:6379> SAVE
OK

This command will create a dump.rdb file in your Redis directory.

Restore Redis Data

To restore Redis data, move Redis backup file (dump.rdb) into your Redis directory and start the server. To get your Redis directory, use CONFIG command of Redis as shown below.

127.0.0.1:6379> CONFIG get dir
1) "dir"
2) "/user/tutorialspoint/redis-2.8.13/src"

In the output of the above command /user/tutorialspoint/redis-2.8.13/src is the directory, where Redis server is installed.

Bgsave

To create Redis backup, an alternate command BGSAVE is also available. This command will start the backup process and run this in the background.

Example

127.0.0.1:6379> BGSAVE
Background saving started

Redis Lists are simply lists of strings, sorted by insertion order. You can add elements in Redis lists in the head or the tail of the list.

Maximum length of a list is 2³² – 1 elements (4294967295, more than 4 billion of elements per list).

Example

redis 127.0.0.1:6379> LPUSH tutorials redis
(integer) 1
redis 127.0.0.1:6379> LPUSH tutorials mongodb
(integer) 2
redis 127.0.0.1:6379> LPUSH tutorials mysql
(integer) 3
redis 127.0.0.1:6379> LRANGE tutorials 0 10
1) "mysql"
2) "mongodb"
3) "redis"

In the above example, three values are inserted in Redis list named ‘tutorials’ by the command LPUSH.

Redis Lists Commands

Following table lists some basic commands related to lists.

Redis server commands are basically used to manage Redis server.

Example

Following example explains how we can get all statistics and information about the server.

redis 127.0.0.1:6379> INFO

# Server
redis_version:2.8.13
redis_git_sha1:00000000
redis_git_dirty:0
redis_build_id:c2238b38b1edb0e2
redis_mode:standalone
os:Linux 3.5.0-48-generic x86_64
arch_bits:64
multiplexing_api:epoll
gcc_version:4.7.2
process_id:3856
run_id:0e61abd297771de3fe812a3c21027732ac9f41fe
tcp_port:6379
uptime_in_seconds:11554
uptime_in_days:0 hz:10
lru_clock:16651447
config_file:

# Clients
connected_clients:1
client_longest_output_list:0
client_biggest_input_buf:0
blocked_clients:0

# Memory
used_memory:589016
used_memory_human:575.21K
used_memory_rss:2461696
used_memory_peak:667312
used_memory_peak_human:651.67K
used_memory_lua:33792
mem_fragmentation_ratio:4.18
mem_allocator:jemalloc-3.6.0

# Persistence
loading:0
rdb_changes_since_last_save:3
rdb_bgsave_in_progress:0
rdb_last_save_time:1409158561
rdb_last_bgsave_status:ok
rdb_last_bgsave_time_sec:0
rdb_current_bgsave_time_sec:-1
aof_enabled:0
aof_rewrite_in_progress:0
aof_rewrite_scheduled:0
aof_last_rewrite_time_sec:-1
aof_current_rewrite_time_sec:-1
aof_last_bgrewrite_status:ok
aof_last_write_status:ok

# Stats
total_connections_received:24
total_commands_processed:294
instantaneous_ops_per_sec:0
rejected_connections:0
sync_full:0
sync_partial_ok:0
sync_partial_err:0
expired_keys:0
evicted_keys:0
keyspace_hits:41
keyspace_misses:82
pubsub_channels:0
pubsub_patterns:0
latest_fork_usec:264

# Replication
role:master
connected_slaves:0
master_repl_offset:0
repl_backlog_active:0
repl_backlog_size:1048576
repl_backlog_first_byte_offset:0
repl_backlog_histlen:0

# CPU
used_cpu_sys:10.49
used_cpu_user:4.96
used_cpu_sys_children:0.00
used_cpu_user_children:0.01

# Keyspace
db0:keys = 94,expires = 1,avg_ttl = 41638810
db1:keys = 1,expires = 0,avg_ttl = 0
db3:keys = 1,expires = 0,avg_ttl = 0

Redis Server Commands

Following table lists some basic commands related to Redis server.

Redis is an open source, advanced key-value store and an apt solution for building highperformance, scalable web applications.

Redis has three main peculiarities that sets it apart.

• Redis holds its database entirely in the memory, using the disk only for persistence.

• Redis has a relatively rich set of data types when compared to many key-value data stores.

• Redis can replicate data to any number of slaves.

Redis Advantages

Following are certain advantages of Redis.

• Exceptionally fast − Redis is very fast and can perform about 110000 SETs per second, about 81000 GETs per second.

• Supports rich data types − Redis natively supports most of the datatypes that developers already know such as list, set, sorted set, and hashes. This makes it easy to solve a variety of problems as we know which problem can be handled better by which data type.

• Operations are atomic − All Redis operations are atomic, which ensures that if two clients concurrently access, Redis server will receive the updated value.

• Multi-utility tool − Redis is a multi-utility tool and can be used in a number of use cases such as caching, messaging-queues (Redis natively supports Publish/Subscribe), any short-lived data in your application, such as web application sessions, web page hit counts, etc.

Redis Versus Other Key-value Stores

• Redis is a different evolution path in the key-value DBs, where values can contain more complex data types, with atomic operations defined on those data types.

• Redis is an in-memory database but persistent on disk database, hence it represents a different trade off where very high write and read speed is achieved with the limitation of data sets that can”t be larger than the memory.

• Another advantage of in-memory databases is that the memory representation of complex data structures is much simpler to manipulate compared to the same data structure on disk. Thus, Redis can do a lot with little internal complexity.

Redis supports 5 types of data types.

Strings

Redis string is a sequence of bytes. Strings in Redis are binary safe, meaning they have a known length not determined by any special terminating characters. Thus, you can store anything up to 512 megabytes in one string.

Example

redis 127.0.0.1:6379> SET name "tutorialspoint"
OK
redis 127.0.0.1:6379> GET name
"tutorialspoint"

In the above example, SET and GET are Redis commands, name is the key used in Redis and tutorialspoint is the string value that is stored in Redis.

Note − A string value can be at max 512 megabytes in length.

Hashes

A Redis hash is a collection of key value pairs. Redis Hashes are maps between string fields and string values. Hence, they are used to represent objects.

Example

redis 127.0.0.1:6379> HMSET user:1 username tutorialspoint password
tutorialspoint points 200
OK
redis 127.0.0.1:6379> HGETALL user:1
1) "username"
2) "tutorialspoint"
3) "password"
4) "tutorialspoint"
5) "points"
6) "200"

In the above example, hash data type is used to store the user”s object which contains basic information of the user. Here HMSET, HGETALL are commands for Redis, while user − 1 is the key.

Every hash can store up to 2³² – 1 field-value pairs (more than 4 billion).

Lists

Redis Lists are simply lists of strings, sorted by insertion order. You can add elements to a Redis List on the head or on the tail.

Example

redis 127.0.0.1:6379> lpush tutoriallist redis
(integer) 1
redis 127.0.0.1:6379> lpush tutoriallist mongodb
(integer) 2
redis 127.0.0.1:6379> lpush tutoriallist rabitmq
(integer) 3
redis 127.0.0.1:6379> lrange tutoriallist 0 10

1) "rabitmq"
2) "mongodb"
3) "redis"

The max length of a list is 2³² – 1 elements (4294967295, more than 4 billion of elements per list).

Sets

Redis Sets are an unordered collection of strings. In Redis, you can add, remove, and test for the existence of members in O(1) time complexity.

Example

redis 127.0.0.1:6379> sadd tutoriallist redis
(integer) 1
redis 127.0.0.1:6379> sadd tutoriallist mongodb
(integer) 1
redis 127.0.0.1:6379> sadd tutoriallist rabitmq
(integer) 1
redis 127.0.0.1:6379> sadd tutoriallist rabitmq
(integer) 0
redis 127.0.0.1:6379> smembers tutoriallist

1) "rabitmq"
2) "mongodb"
3) "redis"

Note − In the above example, rabitmq is added twice, however due to unique property of the set, it is added only once.

The max number of members in a set is 2³² – 1 (4294967295, more than 4 billion of members per set).

Sorted Sets

Redis Sorted Sets are similar to Redis Sets, non-repeating collections of Strings. The difference is, every member of a Sorted Set is associated with a score, that is used in order to take the sorted set ordered, from the smallest to the greatest score. While members are unique, the scores may be repeated.

Example

redis 127.0.0.1:6379> zadd tutoriallist 0 redis
(integer) 1
redis 127.0.0.1:6379> zadd tutoriallist 0 mongodb
(integer) 1
redis 127.0.0.1:6379> zadd tutoriallist 0 rabitmq
(integer) 1
redis 127.0.0.1:6379> zadd tutoriallist 0 rabitmq
(integer) 0
redis 127.0.0.1:6379> ZRANGEBYSCORE tutoriallist 0 1000

1) "redis"
2) "mongodb"
3) "rabitmq"

Redis commands are used to perform some operations on Redis server.

To run commands on Redis server, you need a Redis client. Redis client is available in Redis package, which we have installed earlier.

Syntax

Following is the basic syntax of Redis client.

$redis-cli

Example

Following example explains how we can start Redis client.

To start Redis client, open the terminal and type the command redis-cli. This will connect to your local server and now you can run any command.

$redis-cli
redis 127.0.0.1:6379>
redis 127.0.0.1:6379> PING
PONG

In the above example, we connect to Redis server running on the local machine and execute a command PING, that checks whether the server is running or not.

Run Commands on the Remote Server

To run commands on Redis remote server, you need to connect to the server by the same client redis-cli

Syntax

$ redis-cli -h host -p port -a password

Example

Following example shows how to connect to Redis remote server, running on host 127.0.0.1, port 6379 and has password mypass.

$redis-cli -h 127.0.0.1 -p 6379 -a "mypass"
redis 127.0.0.1:6379>
redis 127.0.0.1:6379> PING
PONG