Should we remove redis-object-cache plugin ?

VirtuBox · 2019-09-15T21:27:41+00:00

Hello, another question for you about redis-object-cache plugin. Currently the plugin is installed by default with the flag --wpredis but several users fac...

dejioke

alexlii1971 redundant system in this context means multi system, i.e multi droplets, multi vps, multi AWS instances in a case whereby you are auto scaling. So it it does not affect multiple websites in a single system, i.e in a single vps or droplet or single cloud instance

alexlii1971

dejioke thanks for message, but I did not get your point.

Anyway, here is a question:

There are two sites on one server, can I enable Wp-Redis on one site and Wp-rocket on another site?

or, do you recommend this method? If not, why?

Thanks

dejioke

alexlii1971 yes you can enable Wp-Redis on one site and Wp-rocket on another site on the same server.
Because Flags are not server-wide, they are per-site-settings.

Choice of settings on each site depends on requirements/preferences of the site.

kingkool68

michacassola I used to run a multi-server WordPress setup using EasyEngine v3 a couple years ago. Slides from a talk I developed about how it was set up http://kingkool68.com/scaling-wordpress-on-aws/#/

I also used Redis for full page caching because I could run one Redis instance to support multiple nodes without any sort of caching conflicts. We had object caching enabled which helped speed up the backend which used several ill-performant queries to power data in custom columns in the WordPress backend.

alexlii1971

VirtuBox I often use WP-Rocket with Nginx fastcgi_cache to decrease server load by using to layer of cache.

This post is great tutorial for cache setting, and anyone would like to explain the term of "layer of cache" here, anyway to set "layer of cache" please?

Thanks

steelliberty

jond1
Hi JonD -- I am very much in a place where I want to expand to a high availability WP cluster -- Do you have any documentation or can suggest some third party docs ? Thank you . .

jond1

steelliberty I haven't had time to finish my documentation unfortunately, been tied up on some projects at my day job. I'd be happy to work with you individually if you want my assistance on it.

https://davidveksler.com/2019/10/20/high-traffic-wordpress-architecture-using-aws-lightsail/ This is something like what I based mine on, but I'm not using Lightsail. My bill is about $500/mo and I can handle any amount of traffic without a sweat. I do offer consulting services if you would like to engage with me directly.

steelliberty

jond1 I installed the object-cache.php file in the wp-content director and removed redis plugin. which removed the redis object-cache.php drop in -- but I am unable to determine that the cache is working .. I install debug-bar and it shows now object-cache and I tried the admin tools dashboard and it was not able to detect any cache .. the redis-server is running and I can store keys and retrieve .. the permissions are correct on the pj-object -- Do you have any idea why it does not appear to be working ? Thank you

jond1

Look in the Query Monitor tool to see if Object Cache is active. Such as this.

slitweb

VirtuBox Hello there!
Currently I am also wondering how exactly caching with --wpredis is done.
For example:
I have setup a WordPress Multisite with subdirectories and --wpredis
I am using Object Cache Pro plugin (by Till Krüss) instead of the preinstalled free object cache plugin by Till Krüss to handle redis object cache in WordPRess.
I know that Nginx Helper plugin also gets installed. And I have always been wondering what this does as there is still no documentation on this.
So from what you wrote in your post above, I am assuming that you use Nginx Helper to handle Full page caching via redis server in this particular constellation.

It would be super helpful, if there was more documentation on this; especially if one uses Cloudflare and Nitropack on a site like this as well.

My questions are:

Do I have have to check the checkbox "enable purge" in Nginx Helper in Network Admin? Then what next? Do I pick redis and if I do that, which redis database will be used? The same as for Object caching? Object caching is using 0. Or should I rather pick fast cgi for page caching? And what next?
In any case: If I select Nginx Helper to handle server side page caching, this will be set on network admin. If I purge cache on any network site within the multisite installation, will the entire page cache of the entire multisite be purged each time? Is this a good solution?
Will cloudflare and / or Nitropack be able to work with this setup properly? Because currently its a mess when it comes to purging / clearing cache.

marty

This would have been better in a new thread. :-)

slitweb Currently I am also wondering how exactly caching with --wpredis is done.

All page caching on WordOps is handled via conf files - different configurations are included depending on which option you use (--wpredis, --wpfc etc). If you look at the site level conf file you'll see how this works (wo site edit <domain>).

slitweb I know that Nginx Helper plugin also gets installed. And I have always been wondering what this does as there is still no documentation on this.

Nginx Helper isn't part of WordOps, it's a plugin from the main WP repository - lots of info on it there:
https://wordpress.org/plugins/nginx-helper/
Short answer is, it's (mainly) for handling purging of the page cache. It doesn't 'do' any caching.

Re 1. Yes if you want relevant pages to be purged, e.g. if someone publishes a new post and you want the homepage to immediately show that new post etc. Pick redis if you're using redis for page caching, pick nginx if you're using nginx for page caching. Simple as that. Again, this is for purging, nothing to do with selecting page caching method.

Re 2. From the Nginx Helper plugin? Probably, never tested it with multisite. You can check by purging and then checking a page from each site before/after - look at the headers returned to see if there is a hit or miss from the cache.

Re 3. Depends what you're doing with those. Choose where you want page caching, don't just do it in everything or it will be a mess. :-)

slitweb

marty
Thanks for your reply.

marty All page caching on WordOps is handled via conf files - different configurations are included depending on which option you use (--wpredis, --wpfc etc). If you look at the site level conf file you'll see how this works (wo site edit <domain>).

Yes, I know. My question was not related to that. I meant for example:

Scenario:
I setup a simple WordPress page with --wpredis.
Nginx helper gets installed (I know its a plugin from the wp repo and that it is not part of wordops... 😉) . Reason for its auto installation and activation through wordops wo site command: its "purging" functionality - to allow a site's admin clearing page cache from within WordPress.
Redis Object Cache (free plugin) also gets auto installed through wordops wo site command. Reason for its installation: being able to connect this wordpress site with local Redis Server and actually be able to provide object caching functionality to this wordpress site.

Next, what do I do?
Then I must pick the Redis option inside Nginx Helper, right? Because it does not make sense to use the Nginx Fastcgi page cache, as the required conf settings won't be available to this site, right? And thus it doesn't make sense to be able to purge it.
if I dont pick Redis or any option in Nginx helper, the site will still be page cached? In this scenario via redis? Or will the page cache be
My problem here is: Redis is a great object caching tool. But I am not so convinced using it for page caching. Why is it automatically used for page caching? This can not be disabled...

To disable it, I will have to set the site to --wp oder --wpfc, right? So this vhost loads the correct nginx configurations.

I will however still be able to use redis object caching, because redis server is available on my machine and I merely need a connector - in this case Redis Object Cache oder Redis Object cache Pro or any other tool that is able to connect a wordpress site to my redis server. Usually these tools provide more granular options for redis table selection, cache groups, settings for woocommerce and much more. I highly recommend using Redis Object Cache Pro for that purpose. It comes bundled with monthly costs, but object caching on a larger shop system with woocommerce and being able to control it perfectly is crucial in my opinion.

Also I am not sure, how to make more granular settings regarding page caching at all without these helper tools...

So while we are at this topic:
If I set WP Cache constant to true on a site that has been created using wordops site command with merely --wp - then what happens under the hood? Is anything happening at all?
Some form of page caching is being applied, because in that case, I am seeing several issues regarding event tracking and event firing when using PixelYourSite. I was thinking that maybe there is something in PixelYourSite's code that is responding to WP Cache constant set to true. But if in fact no page cache is applied... then .. gosh my brain.

marty

slitweb Next, what do I do? ...

If you install a site with --wpfc, you're using Nginx page caching, so set Nginx Helper to purge Nginx.

If you install a site with --wpredis, you're using Redis for page caching, so set Nginx Helper to purge Redis. If you also want Redis Object Cache, you enable that plugin.

If you want to use Nginx page cache + Redis object cache, you can do that too, but it’s not directly supported by WordOps. You can make it work by creating the site with --wpredis (so Redis server gets installed) and then updating the site to --wpfc.

slitweb So while we are at this topic:

This isn't really related to WordOps. Pixel tracking scripts like PixelYourSite are client-side JavaScript, so page caching won't affect their behavior beyond whether the tracking code is present in the page (you can check this via “View Page Source”). From there, it’s all JavaScript running in the browser. If you’re still having issues, it's best to reach out to PixelYourSite support.

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