perf: store donation meta data results under correct cache key

[ravinderk]

Bug Report

User Story

As an admin, I want my website to load faster, but currently, I am seeing additional meta queries on each page load ( Query Monitor ).

ref: https://secure.helpscout.net/conversation/759921560/0/?folderId=672194

Current Behavior

We are using WP_Query to get donations or form then by default WordPress loads metadata of each donation to cache within post_meta key.

https://github.com/WordPress/WordPress/blob/32ee2ed5734357d5faa5537d9916ada07f672eaf/wp-includes/meta.php#L888

We have custom meta table for donation and form, so whenever we do meta query then we define meta_type and it is used to search meta query result in cache. We always get cache miss because cache always store under post_meta key instead of donation_meta
https://github.com/WordPress/WordPress/blob/32ee2ed5734357d5faa5537d9916ada07f672eaf/wp-includes/meta.php#L520

We can reduce a lot of query by storing meta cache under correct cache key.

Acceptance Criteria

• Meta query result does store into correct meta cache object. For example, meta cache stores into donation_meta if meta type is donation
• Meta cache updates when editing donation

[kevinwhoffman]

@ravinderk Please complete the issue template so we can understand how this affects the user. It's unclear whether this affects front end or back end performance, or both. Every issue also needs acceptance criteria.

[ravinderk]

@kevinwhoffman This was an old issue which I created. I added few lines to remind myself. I will update this by tomorrow

[ravinderk]

@kevinwhoffman I changed the title and scope of this issue. We will fix donation meta cache related issue in this and i will add another issue for form and donor

[ravinderk]

reopening this issue to test again with #3983 and #3982