DB cache flush

  • Resolved mandigo97

    (@lukomandigo97)


    1 year, 2 months ago

    Hello, I have been using the w3 cache plugin for about 2 weeks. I subscribed. My saves are set up like this:

    Page cache Disk: Enhanced

    Object Cache (Redis)

    Database Cache (Redis)

    The big problem is that I noticed an awful lot of cache deletions.

    What can I do about it? From the debug I found out that rankmath seo is clearing the cache. I managed to solve this, but still these numbers:

    Calls/period: 1,138,147

    Calls/sec: 385.0

    Hit rate: 5 %

    Cache flushes: 18,086

    Time taken: 1,366,482 ms

    What I’m still using is woocommerce. But I don’t know how to proceed. Unfortunately, I don’t know much about debugging. There was 1 flush event, that’s also woocommerce, but it doesn’t run more than ten thousand times per minute. I would like some help and ideas on what is causing this. Unfortunately, it is quite difficult to create a cache on the site like this.

Viewing 8 replies - 1 through 8 (of 8 total)
  • Plugin Contributor Marko Vasiljevic

    (@vmarko)

    1 year, 2 months ago

    Hello @lukomandigo97

    Thank you for reaching out and I am happy to help!
    Can you please share if those nubers are for Page Cahcing or DB caching and depending on that, have you enabled the Purge logs for specific module that will show what triggered the purge?

    Thanks!

    Thread Starter mandigo97

    (@lukomandigo97)

    1 year, 2 months ago

    This is the db cache. What I find strange is that the radish itself never emptied. It has 5GB of storage space, but it fills up very quickly. The hit rate is around 90%, which is pretty good. The DB cache is very low, only between 5-10%, which I mentioned. But why isn’t redis deleted when the flush all command is run? Is it possible that the problem isn’t the deletion, but that redis itself is full and the db cache is deleted because there isn’t enough space to store it?

    Redis policy: allkeys-lru

    Cache lifetime: 3 days

    Plugin Contributor Marko Vasiljevic

    (@vmarko)

    1 year, 2 months ago

    Hello @lukomandigo97

    Thank you your feedback.
    Can you please try to mannually flush Redis:

    • FLUSHDB – clears currently active database
    • FLUSHALL – clears all the existing databases

    Are you using a single Redis instance for both Object Cahcing and DB Cahcing

    Thanks!

    Thread Starter mandigo97

    (@lukomandigo97)

    1 year, 2 months ago

    The command has been executed.

    If I understand correctly, they need to be stored in a separate redis instance? Or do I need to create a redis namespace? I haven’t done this before 🙂

    Plugin Contributor Marko Vasiljevic

    (@vmarko)

    1 year, 2 months ago

    Hello @lukomandigo97

    Thank you for your feedback.
    This depends on the website, however ideally you should use a separate Redis instance to avoid this.
    The reason is that you are using both DB and Object Caching, and there are a lot of objects to be cached 😀
    You may want to only use Object Caching instead of using both

    I hope this helps!

    Thread Starter mandigo97

    (@lukomandigo97)

    1 year, 2 months ago

    I managed to set a new database id. But I don’t see much change, the hit rate is now around 15-20%. I don’t really understand the flush number, it has decreased, but does this show the flush number at that minute or all-time? Unfortunately it’s still quite slow, or is there another idea?

    The statistics don’t indicate it, but the database size is this: db1:keys=228751,expires=228747,avg_ttl=236149554

    Thread Starter mandigo97

    (@lukomandigo97)

    1 year, 2 months ago

    and 1 more comment, if this means anything. The object cache is not used in the statistics.

    But if I go to the object cache menu item, this is what I get:

    Object caching via Redis is currently enabled.

    Plugin Contributor Marko Vasiljevic

    (@vmarko)

    1 year, 2 months ago

    Hello @lukomandigo97

    Can you please share the website URL and what exactly is slow?

    Thanks!

Viewing 8 replies - 1 through 8 (of 8 total)

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