Nosql-memcached related

First, memcached

1.1. Installation

Cd/usr/local/src
wget http://memcached.org/latest
TAR-ZXVF memcached-1.x.x.tar.gz
CD memcached-1.x.x
./configure && make && make test && make install

1.2. Install the Client

Pip Install python-memcached

1.3. Start Memcache

Memcached-d-M 10-u root-l 127.0.0.1-p 12000-c 256-p/export/servers/memcache/logs/memcache.pid

-P Specify port number (default 11211)

-m specifies the maximum amount of memory to use (default 64MB)

-T thread count (default 4)

-L connected IP address, default is native

-D starts with the daemon process

-C Maximum Simultaneous connection number, default is 1024-p to develop Memecache PID file

-H Printing Help information

Second, memcached module

2.1, PYTHON-MEMCACHD module natively support cluster operation, the principle is to maintain a host list in memory, and the weight of the host in the cluster and the host in the list of repeated occurrences of the number is proportional.

Host weights
1.1.1.1 1
1.1.1.2 2
1.1.1.3 1

then the list of hosts in memory is: host_list=[' 1.1.1.1 ', ' 1.1.1.2 ', ' 1.1.1.2 ', ' 1.1.1.3 ',]

2.2, see an example, Python operation memcache Cluster

MC = Memcache. Client ([' 1.1.1.1:12000 ', 1), (' 1.1.1.2:12000 ', 2), (' 1.1.1.3:12000 ', 1)], debug=true)
Mc.set (' K1 ', ' v1 ')

2.3, Memcache common operation:

• Storage command: Set/add/replace/append/prepend/cas
• Get command: Get/gets
• Other commands: Delete/stats.

①, Add Method:

Import Memcache

MC = Memcache. Client ([' 192.168.48.128:11211 '], debug=true)
# Mc.set ("foo", "Bar")
# ret = mc.get ("foo")
Mc.add (' K1 ', ' v1 ')
Mc.add (' K1 ', ' v1 ')
# Print (ret)

②, replace method:

Replace modifies the value of a key, or the exception if key does not exist.

Import Memcache

MC = Memcache. Client ([' 192.168.48.128:11211 '], debug=true)
# Mc.set ("foo", "Bar")
# ret = mc.get ("foo")
Mc.add (' K1 ', ' v1 ')
# mc.add (' K1 ', ' v1 ')
# Print (ret)
Mc.replace ("K1", "666")
Print (Mc.get ("K1"))
Results:
666

③, set, and Set_multi methods

Set: Sets a key-value pair, if key does not exist, is created if key exists, then modified;
Set_multi: Sets multiple key-value pairs, if key does not exist, is created and modified if key exists.

Import Memcache

MC = Memcache. Client ([' 192.168.48.128:11211 '], debug=true)
Mc.set ("K10", "V10")
Mc.set_multi ({"K11": "V11", "K12": "V12"})

the difference between the Set method and the Add method: set = add + Replace

④, delete, and Delete_multi methods

Delete: Deletes a specified key-value pair in the memcached;
Delete_multi: Deletes the specified number of key-value pairs in memcached.

Import Memcache

MC = Memcache. Client ([' 192.168.48.128:11211 '], debug=true)
# Mc.set ("K10", "V10")
# Mc.set_multi ({"K11": "V11", "K12": "V12"})

Mc.delete ("K10")
Mc.delete_multi (["K11", "K12"])

⑤, get, and Get_multi methods

Get: Gets a key value pair;
Get_multi: Gets multiple key-value pairs.

Import Memcache
MC = Memcache. Client ([' 192.168.48.128:11211 '], debug=true)
Mc.set ("K10", "V10")
Mc.set_multi ({"K11": "V11", "K12": "V12"})
val = mc.get (' K1 ')
Print (val)

Item_dict = Mc.get_multi ([' K11 ', ' K12 '])
Print (item_dict)

⑥, append, and Prepend methods

Append: Modifies the value of the specified key, appending the content after the value;
Prepend: Modifies the value of the specified key to insert the contents before the value.

Import Memcache
MC = Memcache. Client ([' 192.168.10.128:12000 '], debug=true)
Mc.append (' K1 ', ' after ')
Val1 = Mc.get (' K1 ')
Print (VAL1)
Mc.prepend (' K1 ', ' brefore ')
Val2 = Mc.get (' K1 ')
Print (VAL2)
#结果:
V1afterafter
Breforev1afterafter

⑦, Other methods:

Stats: View historical operations

gets and CAS: the problem of data contention and dirty data (data confusion) must be bypassed by using the cache system to share data resources

Suppose that the remaining number of a product in a mall is saved in memcache, Product_count = 900
A user Refresh page reads from Memecache to Product_count = 900
b User Refresh page read from Memecache to Product_count = 900
A, a, a user buys a product and modifies the value of Product_count
A modified, Product_count = 899
b after modification, Product_count = 899
But the correct number should be 898, and the data will be chaotic.
If you want to avoid this situation, you can use Get and CAs

• Note: To add the Cache_cas parameter to the client

Import Memcache
MC = Memcache. Client ([' 192.168.48.131 '],cache_cas=true)
Mc.set (' count ', "100")
Print (Mc.gets ("Count"))
# Mc.set ("Count", ' 1000 ')
result = Mc.cas ("Count", "99")
Print (Result)
Print (Mc.get ("Count"))

Nosql-memcached related