# Predefined Constants

The constants below are defined by this extension, and will only be available when the extension has either been compiled into PHP or dynamically loaded at runtime.

MySQL Memcache Plugin related

`MYSQLND_MEMCACHE_DEFAULT_REGEXP` (string)
  Default regular expression (PCRE style) used for matching `SELECT` statements that will be mapped into a MySQL Memcache Plugin access point, if possible. It is also possible to use mysqlnd_memcache_set(), but the default approach is using this regular expression for pattern matching.

Assorted

The version number of this plugin can be obtained by using `MYSQLND_MEMCACHE_VERSION` or `MYSQLND_MEMCACHE_VERSION_ID`. `MYSQLND_MEMCACHE_VERSION` is the string representation of the numerical version number `MYSQLND_MEMCACHE_VERSION_ID`, which is an integer such as 10000. Developers can calculate the version number as follows.

Version (part) | Example
--- | ---
Major*10000 | 1*10000 = 10000
Minor*100 | 0*100 = 0
Patch | 0 = 0
MYSQLND_MEMCACHE_VERSION_ID | 10000

`MYSQLND_MEMCACHE_VERSION` (string)
  Plugin version string, for example, 1.0.0-alpha.
`MYSQLND_MEMCACHE_VERSION_ID` (int)
  Plugin version number, for example, 10000.