Redis Learning 09 - Multi-database and Server Command

I. Multi-database

A Redis instance can contain multiple databases. Each client can specify which database to connect to a Redis instance, just like creating multiple databases in a mysql, and the client can specify which database to connect to.

A Redis instance can provide up to 16 databases with subscripts ranging from 0 to 15. The client defaults to database 0, or can select which database to connect to, as follows

Select Library 1

127.0.0.1:6379> select 1
OK
127.0.0.1:6379[1]> keys *
(empty list or set)

Select Library 0

127.0.0.1:6379[1]> select 0
OK
127.0.0.1:6379> keys *
 1) "mysortedset"
 2) "myset3"
 3) "mylist2"
 4) "mylist"
 5) "myset2"
 6) "username"
 7) "myset4"
 8) "myset1"
 9) "mylist3"
10) "myhash"
11) "mysorted"

Two. Move library

Order:

move key db

Meaning:
Move the key of the current library to the db Library

Example

127.0.0.1:6379> select 1
OK
127.0.0.1:6379[1]> keys *
(empty list or set)
127.0.0.1:6379[1]> select 0
OK
127.0.0.1:6379> move mysorted 1
(integer) 1
127.0.0.1:6379> select 1
OK
127.0.0.1:6379[1]> keys *
1) "mysorted"
127.0.0.1:6379[1]> zrange mysorted 0 -1
1) "wiming"
2) "xiaoming"

3. Server commands

3.1 ping

Order:

ping [message]

Meaning:
Test whether the connection survives

Example

127.0.0.1:6379> ping 
PONG
127.0.0.1:6379> ping xiaoming
"xiaoming"

Now let's turn off the server to test it.

127.0.0.1:6379> ping 
Could not connect to Redis at 127.0.0.1:6379: Connection refused

3.2 echo

Order:

echo message

Meaning:
Print something on the command line

Example

127.0.0.1:6379> echo wiming
"wiming"

3.3 select

Order:

select db

Meaning:
Select the database, numbered from 0-15

Example

127.0.0.1:6379> select 2
OK
127.0.0.1:6379[2]> select 0
OK

3.4 quit

Order:

quit

Meaning:
Exit connection

Example

127.0.0.1:6379> quit 
[root@wiming bin]# 

3.5 dbsize

Order:

dbsize

Meaning:
Get the number of key s in the current database

Example

127.0.0.1:6379> dbsize
(integer) 10

3.6 info

Order:

info

Meaning:
Access to server information and statistics

Example

127.0.0.1:6379> info
# Server
redis_version:4.0.2
redis_git_sha1:00000000
redis_git_dirty:0
redis_build_id:17ae9636a5224df7
redis_mode:standalone
os:Linux 3.10.0-123.el7.x86_64 x86_64
arch_bits:64
multiplexing_api:epoll
atomicvar_api:atomic-builtin
gcc_version:4.8.2
process_id:17733
run_id:b09701789073b432652ef68cb5c7ecd5b6fd9a5c
tcp_port:6379
uptime_in_seconds:404
uptime_in_days:0
hz:10
lru_clock:13443152
executable:/usr/local/redis/bin/./redis-server
config_file:/usr/local/redis/bin/redis.conf
.......Output is omitted.........

3.7 flushdb

Order:

flushdb

Meaning:
Delete all key s in the current database

Example

127.0.0.1:6379[1]> keys *
1) "mysorted"
2) "name"
3) "age"
127.0.0.1:6379[1]> flushdb
OK
127.0.0.1:6379[1]> keys *
(empty list or set)

3.8 flushall

Order:

flushall

Meaning:
Get all key s in all databases

Example

127.0.0.1:6379[1]> set name wiming
OK
127.0.0.1:6379[1]> set age 18
OK
127.0.0.1:6379[1]> keys *
1) "age"
2) "name"
127.0.0.1:6379[1]> select 0
OK
127.0.0.1:6379> keys *
 1) "mylist3"
 2) "mylist"
 3) "myset4"
 4) "myset2"
 5) "mysortedset"
 6) "myset3"
 7) "myhash"
 8) "myset1"
 9) "mylist2"
10) "username"
127.0.0.1:6379> flushall
OK
127.0.0.1:6379> keys *
(empty list or set)
127.0.0.1:6379> select 1
OK
127.0.0.1:6379[1]> keys *
(empty list or set)