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Runtime Configuration

The behaviour of these functions is affected by settings in php.ini.

Memcache Configuration Options
Name Default Changeable Changelog
memcache.allow_failover "1" INI_ALL Available since memcache 2.0.2.
memcache.max_failover_attempts "20" INI_ALL Available since memcache 2.1.0.
memcache.chunk_size "8192" INI_ALL Available since memcache 2.0.2.
memcache.default_port "11211" INI_ALL Available since memcache 2.0.2.
memcache.hash_strategy "standard" INI_ALL Available since memcache 2.2.0.
memcache.hash_function "crc32" INI_ALL Available since memcache 2.2.0.
memcache.protocol ascii INI_ALL Supported since memcache 3.0.0
memcache.redundancy 1 INI_ALL Supported since memcache 3.0.0
memcache.session_redundancy 2 INI_ALL Supported since memcache 3.0.0
memcache.compress_threshold 20000 INI_ALL Supported since memcache 3.0.3
memcache.lock_timeout 15 INI_ALL Supported since memcache 3.0.4
Session Configuration Options Affecting Memcache Behavior
Name Default Changeable Changelog
session.save_handler "files" INI_ALL Supported since memcache 2.1.2
session.save_path "" INI_ALL Supported since memcache 2.1.2
For further details and definitions of the INI_* modes, see the Where a configuration setting may be set.

Here's a short explanation of the configuration directives.

memcache.allow_failover bool
Whether to transparently failover to other servers on errors.
memcache.max_failover_attempts int
Defines how many servers to try when setting and getting data. Used only in conjunction with memcache.allow_failover.
memcache.chunk_size int
Data will be transferred in chunks of this size, setting the value lower requires more network writes. Try increasing this value to 32768 if noticing otherwise inexplicable slowdowns.
memcache.default_port string
The default TCP port number to use when connecting to the memcached server if no other port is specified.
memcache.hash_strategy string
Controls which strategy to use when mapping keys to servers. Set this value to consistent to enable consistent hashing which allows servers to be added or removed from the pool without causing keys to be remapped. Setting this value to standard results in the old strategy being used.
memcache.hash_function string
Controls which hash function to apply when mapping keys to servers, crc32 uses the standard CRC32 hash while fnv uses FNV-1a.
memcache.protocol string
memcache.redundancy int
memcache.session_redundancy int
memcache.compress_threshold int
memcache.lock_timeout int
session.save_handler string
Use memcache as a session handler by setting this value to memcache.
session.save_path string
Defines a comma separated of server urls to use for session storage, for example "tcp://host1:11211, tcp://host2:11211". Each url may contain parameters which are applied to that server, they are the same as for the Memcache::addServer() method. For example "tcp://host1:11211?persistent=1&weight=1&timeout=1&retry_interval=15"