[wp-trac] [WordPress Trac] #43112: set_transient uses object-cache as storage instead of cache layer

[WordPress Trac]

#43112: set_transient uses object-cache as storage instead of cache layer
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 Reporter:  batooo       |       Owner:
     Type:  enhancement  |      Status:  closed
 Priority:  normal       |   Milestone:
Component:  Cache API    |     Version:  4.9.1
 Severity:  normal       |  Resolution:  invalid
 Keywords:               |     Focuses:
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Changes (by dd32):

 * status:  new => closed
 * resolution:   => invalid
 * milestone:  Awaiting Review =>


Comment:

 Hi @batooo and welcome to Trac.

 The transient functions are specifically cache functions, and are not
 designed to be used for storage.
 WordPress has three main "option" type stores:
  - Options. Persistent data stored in the Database and cached in memory
  - Object Cache. Non-persistent data not stored in the database and only
 in memory if enabled.
  - Transients. Non-persistent data backed by either the Object cache (if
 enabled) or the Database otherwise.

 Each storage option offers different levels of persistence, depending on
 the actual need of the code. It's expected that Transients will remain
 available for 0 ~ `$timeout` seconds, and it's by design that they may be
 purged from memory instantly.

 If you choose to utilise PHP's APCu functionalities, you should expect the
 transient & object cache data to be dumped upon restart. If you choose to
 use Memcache or Redis as the object cache, the data will be there until
 purged or those services are restarted/etc.
 The time to retrieve such items from the normal key-value object caches is
 generally faster than fetching from MySQL directly (or allowing MySQL to
 handle other queries)

 Since this is by design, I'm closing this as `invalid` but hopefully the
 above will help you understand the uses of the various storage options.

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Ticket URL: <https://core.trac.wordpress.org/ticket/43112#comment:6>
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