(PECL memcache >= 0.2.0)

Memcache::incrementIncrement item's value


Memcache::increment(string $key, int $value = 1): int|false

Memcache::increment() increments value of an item by the specified value. If item specified by key was not numeric and cannot be converted to a number, it will change its value to value. Memcache::increment() does not create an item if it doesn't already exist.


Do not use Memcache::increment() with items that have been stored compressed because subsequent calls to Memcache::get() will fail.

Also you can use memcache_increment() function.



Key of the item to increment.


Increment the item by value.

Return Values

Returns new items value on success or false on failure.


Example #1 Memcache::increment() example


/* procedural API */
$memcache_obj = memcache_connect('memcache_host', 11211);
/* increment counter by 2 */
$current_value = memcache_increment($memcache_obj, 'counter', 2);

/* OO API */
$memcache_obj = new Memcache;
$memcache_obj->connect('memcache_host', 11211);
/* increment counter by 3 */
$current_value = $memcache_obj->increment('counter', 3);


See Also

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User Contributed Notes 5 notes

jay dot paroline at escapemg dot com
15 years ago
Instead of checking the value before incrementing, you can simply ADD it instead before incrementing each time. If it's already there, your ADD is ignored, and if it's not there, it's set.

If you add($memcacheKey, 0) and then increment($memcacheKey, 1) in that order, you avoid all possible race conditions. If two threads are running this code concurrently, you will always end up with your value being 2 no matter which order the threads execute in.
15 years ago
Please note:
If the key does not exist, memcache does NOT return false (as you might expect) but 0.
You won't get any hint that the key did not exist and still does not exist and that nothing was incremented.
perroazul64 at gmail dot com
13 years ago
When the key doesn't exist it may return either bool(false) or int(0) (I get different return values on different servers), so be careful if you check for something like ($memcache->increment($key) === false).
ian at blip dot fm
15 years ago
Be careful to use Memcache::decrement() and never Memcache::increment() with a negative value.

The check that prevents Memcache::decrement() from going negative is not in place with Memcache::increment(), so you can end up with a garbage integer on the order of 18 quintillion stored in place of the expected value.
19 years ago
if no variable exists, even if you specify an increment value, the result will be null.

if you're using this for a mutex, chk if its null, and if so, then ADD the variable.
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