visualizer / vendor / phpoffice / phpspreadsheet / docs / topics / memory_saving.md

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1	# Memory saving
2
3	PhpSpreadsheet uses an average of about 1k per cell in your worksheets, so
4	large workbooks can quickly use up available memory. Cell caching
5	provides a mechanism that allows PhpSpreadsheet to maintain the cell
6	objects in a smaller size of memory, or off-memory (eg: on disk, in APCu,
7	memcache or redis). This allows you to reduce the memory usage for large
8	workbooks, although at a cost of speed to access cell data.
9
10	By default, PhpSpreadsheet holds all cell objects in memory, but
11	you can specify alternatives by providing your own
12	[](https://www.php-fig.org/psr/psr-16/PSR-16](https://www.php-fig.org/psr/psr-16/](https://www.php-fig.org/psr/psr-16/) implementation. PhpSpreadsheet keys
13	are automatically namespaced, and cleaned up after use, so a single cache
14	instance may be shared across several usage of PhpSpreadsheet or even with other
15	cache usages.
16
17	To enable cell caching, you must provide your own implementation of cache like so:
18
19	``` php
20	$cache = new MyCustomPsr16Implementation();
21
22	\PhpOffice\PhpSpreadsheet\Settings::setCache($cache);
23	```
24
25	A separate cache is maintained for each individual worksheet, and is
26	automatically created when the worksheet is instantiated based on the
27	settings that you have configured. You cannot change
28	the configuration settings once you have started to read a workbook, or
29	have created your first worksheet.
30
31	## Beware of TTL
32
33	As opposed to common cache concept, PhpSpreadsheet data cannot be re-generated
34	from scratch. If some data is stored and later is not retrievable,
35	PhpSpreadsheet will throw an exception.
36
37	That means that the data stored in cache must not be deleted by a
38	third-party or via TTL mechanism.
39
40	So be sure that TTL is either de-activated or long enough to cover the entire
41	usage of PhpSpreadsheet.
42
43	## Common use cases
44
45	PhpSpreadsheet does not ship with alternative cache implementation. It is up to
46	you to select the most appropriate implementation for your environment. You
47	can either implement [](https://www.php-fig.org/psr/psr-16/PSR-16](https://www.php-fig.org/psr/psr-16/](https://www.php-fig.org/psr/psr-16/) from scratch,
48	or use [](https://packagist.org/search/?q=psr-16pre-existing libraries](https://packagist.org/search/?q=psr-16](https://packagist.org/search/?q=psr-16).
49
50	One such library is [](https://www.php-cache.com/PHP Cache](https://www.php-cache.com/](https://www.php-cache.com/) which
51	provides a wide range of alternatives. Refers to their documentation for
52	details, but here are a few suggestions that should get you started.
53
54	### APCu
55
56	Require the packages into your project:
57
58	```sh
59	composer require cache/simple-cache-bridge cache/apcu-adapter
60	```
61
62	Configure PhpSpreadsheet with something like:
63
64	```php
65	$pool = new \Cache\Adapter\Apcu\ApcuCachePool();
66	$simpleCache = new \Cache\Bridge\SimpleCache\SimpleCacheBridge($pool);
67
68	\PhpOffice\PhpSpreadsheet\Settings::setCache($simpleCache);
69	```
70
71	### Redis
72
73	Require the packages into your project:
74
75	```sh
76	composer require cache/simple-cache-bridge cache/redis-adapter
77	```
78
79	Configure PhpSpreadsheet with something like:
80
81	```php
82	$client = new \Redis();
83	$client->connect('127.0.0.1', 6379);
84	$pool = new \Cache\Adapter\Redis\RedisCachePool($client);
85	$simpleCache = new \Cache\Bridge\SimpleCache\SimpleCacheBridge($pool);
86
87	\PhpOffice\PhpSpreadsheet\Settings::setCache($simpleCache);
88	```
89
90	### Memcache
91
92	Require the packages into your project:
93
94	```sh
95	composer require cache/simple-cache-bridge cache/memcache-adapter
96	```
97
98	Configure PhpSpreadsheet with something like:
99
100	```php
101	$client = new \Memcache();
102	$client->connect('localhost', 11211);
103	$pool = new \Cache\Adapter\Memcache\MemcacheCachePool($client);
104	$simpleCache = new \Cache\Bridge\SimpleCache\SimpleCacheBridge($pool);
105
106	\PhpOffice\PhpSpreadsheet\Settings::setCache($simpleCache);
107	```
108