Redis regular expression operation in PHP applications

Redis is a high-performance key-value storage system that supports a variety of data structures, including strings, hash tables, lists, sets, ordered sets, etc. At the same time, Redis also supports regular expression matching and replacement operations on string data, which makes it highly flexible and convenient in developing PHP applications.

To use Redis for regular expression operations in PHP applications, you need to install the phpredis extension first. This extension provides an API for communicating with the Redis server. The installation method can be achieved by running the following command in the terminal:

pecl install redis

After the configuration is completed, after starting the Redis server and PHP application, you can use regular expressions to operate the Redis database. The following are five regular expression operations for Redis.

1. Get keys matching the specified pattern

Redis command: KEYS pattern

This command can return all key names matching the specified pattern. The pattern pattern can include the following special characters:

• *: Match any number of characters
• ?: Match any single character
• []: Match the specified character set Any character of

#For example, the following command can be used to obtain all keys starting with "user":

$redis->keys('user*');

2. Get the corresponding key of the specified key Value

Redis command: GET key

This command returns the string value corresponding to the specified key. If the key does not exist, returns nil. For example, the following command can be used to get the value of a key named "username":

$value = $redis->get('username');

3. Set key value

Redis command: SET key value [EX seconds] [ PX milliseconds] [NX|XX]

This command can be used to set the value of the specified key. If the key already exists, the original value will be overwritten. Among them, the optional parameters seconds and milliseconds represent the expiration time of the key value, and the units are seconds and milliseconds respectively. NX and XX are mutually exclusive options. When setting the key value, specifying the NX option means setting it only if the key does not exist, while specifying the XX option means setting it only if the key already exists.

For example, the following command can be used to set the value of the key named "username" to "redis" and the expiration time to 600 seconds:

$redis->set('username', 'redis', 600);

4. All keys matching the specified pattern Name

Redis command:SCAN cursor [MATCH pattern] [COUNT count]

This command is used to iterate all key names in the database, optional parameters pattern and count Same as the KEYS command, it can be used to match key names in a specified pattern and set the number of key names returned. In order to avoid returning too many key names in one operation, this command splits the iteration operation into multiple times and returns a portion of the key names in each operation. Each key name is returned with a cursor, which can be passed as a parameter to the SCAN command in the next iteration operation.

For example, the following command can be used to get all key names starting with "user":

$cursor = 0;
$pattern = 'user*';
$keys = [];
do {
    $result = $redis->SCAN($cursor, 'MATCH '.$pattern);
    $cursor = $result[0];
    $keys = array_merge($keys, $result[1]);
} while ($cursor != 0);

5. Regular expression replacement string value

Redis command:EVAL script numkeys key [key ...] arg [arg ...]

This command can execute a customized Lua script, and the regular expression of string values ​​can be realized through Lua script replacement operation. Among them, the script parameter is the code of the Lua script, and the key can be one or more key names. These key names can be used in the Lua script to obtain and modify the corresponding values. arg is an optional parameter that can be used to pass other parameters to the Lua script.

The following is an example of using a Lua script to implement the replacement process:

local key = KEYS[1]
local pattern = ARGV[1]
local replacement = ARGV[2]
redis.call('SET', key, string.gsub(redis.call('GET', key), pattern, replacement))

This script can be used to replace specific content in the string value with the key name key. The pattern and replacement parameters in the script represent regular expressions and replacement strings respectively. Use the string.gsub() function to perform string replacement operations.

For example, the following command can be used to execute the above Lua script and replace all numbers in the key value named "username" with "":

$redis->eval($script, ['username'], ["/%d+/", '']);

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