Selectively disabling database or object caching

  • Resolved verysiberian

    (@verysiberian)


    2 years, 4 months ago

    Hello,

    My site uses a snippet to automatically generate a unique ID for a user at various points in the workflow (related to passing an exam). This worked normally until today, when someone processed several of them in relatively short period of time. About 15 users ended up with identical IDs when they’re supposed to be unique. There is nothing in the code that explains this. Three days ago, I enabled database caching (memcached) and object caching (memcached) through your plugin. I am not blaming the plugin for this behavior — after all, I enabled these options — but am wondering:

    1. Is database or object caching a plausible cause of this abnormal behavior?

    2. Is it possible to selectively disable database and/or object caching for certain operations like this one that did not go well, or must it be an all-or-nothing setting?

    Thanks,
    Very Siberian

Viewing 6 replies - 1 through 6 (of 6 total)
  • Plugin Contributor Marko Vasiljevic

    (@vmarko)

    Hello @verysiberian

    Thank you for reaching out and I am happy to assist you with this.
    If the issue was specifically related to OC or DB caching, it would be manifested immediately and not after 3 days.
    To test this, you should disable the options and see if the problem continues to persist. In DB cahcing and Object Caching options, You should make sure that the caching is not enabled for logged-in users also, and as for the second question, you can add the specific query stems that should not be cached in Performance>Database Cache, or exclude the words, pages:
    Ignored query stems:
    Reject query words:
    Reject constants:
    Never cache the following pages:
    As for the Object Cache, if you know the cache group name, you can add it in the Performance>Object Cache>Non-persistent groups:

    I hope this helps!

    Thanks!

    Thread Starter verysiberian

    (@verysiberian)

    Thank you! And I must not have been clear, but the issue did occur immediately, not three days later. You may have thought that this was related to my other support ticket, but it was not. ??

    I appreciate the suggestions and will try them.

    Best regards,
    Very Siberian

    Thread Starter verysiberian

    (@verysiberian)

    Sorry, one more question: there is no option to disable caching for logged in users under object caching. By contrast, such an option is visible for database caching. Please let me know if I’m missing something. Thanks!

    Plugin Contributor Marko Vasiljevic

    (@vmarko)

    Hey @verysiberian

    Thank you for the clarification.
    I was referring to your statement in this form post:

    Three days ago, I enabled database caching (memcached) and object caching (memcached) through your plugin.

    This worked normally until today,

    Sorry if I misunderstood. ??
    As for the Object Cashing, make sure that the option Enable caching for wp-admin requests is not enabled.

    Thanks!

    Thread Starter verysiberian

    (@verysiberian)

    Thanks for clarifying!

    Thread Starter verysiberian

    (@verysiberian)

    Hello again,

    I really appreciate your plugin and your replies. If you can tolerate a couple more questions, I should be all set for a while. ??

    1. Object caching: I need to make sure that it does not occur for logged in users. You wrote:

    As for the Object Cashing, make sure that the option Enable caching for wp-admin requests is not enabled.

    I did that, but basically all of my logged in users are not seeing the WP admin backend. They are logged into the site and doing things on the frontend. Hence, my question is whether that setting you listed will be sufficient to prevent object caching for any logged in users.

    2. What are your recommendations for database cache and object cache when the two visible choices are Shared Server: Disk and Multiple Servers: Memcached? Which is the preferred option? For page caching, your plugin natively provides a recommendation (Shared Server: Disk Enhanced is Best), so I’m wondering about the other two.

    Best regards,
    Very Siberian

Viewing 6 replies - 1 through 6 (of 6 total)
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