Short:
It seems that a edited page never gets in the queue for purging.
Description:
Initial conditions
Purge_query_url table: empty
Drupal: cleared cache
Purge_queue: empty
Typical Drupal, there are no additional blocks on the pages, Bartik.
There are three internal pages on the site:
drupalvm.dev/timka
drupalvm.dev/simple
drupalvm.dev/big-with-images
=== Experiment 1 ===
1. Step 1
I visited these pages:
drupalvm.dev
drupalvm.dev/timka
drupalvm.dev/simple
drupalvm.dev/big-with-images
All this pages was added to Purge_query_url
2. Step 2
Now I log in to the site and edit drupalvm.dev/timka page (Edit tab — Save — Main page — drupalvm.dev/timka)
After that in Purge_query_url I have only (I still logged in user):
drupalvm.dev/simple
drupalvm.dev/big-with-images
Purge_query:
empty
3. Step 3
Log out.
Deleted urls will appear in Purge_query_url only when you visit them again.
As a result:
I changed the page, but these changes did not affect the external cache. Edited url was removed from the Purge_query_url (because I visit it while was logged in) table and did not fall into Purge_queue table.
All URLs that I visit until authorized will be removed.
Nothing is added to the Purge_query table.
It turns out that in this case the functional doesn't work?
=== Experiment 2 ===
Add to all pages a block with the Recent content.
Step 1:
Visit all urls:
drupalvm.dev
drupalvm.dev/timka
drupalvm.dev/simple
drupalvm.dev/big-with-images
All these pages was added to Purge_query_url
Step 2:
Log in.
Main page — drupalvm.dev/timka — edit — save — main page.
In the Purge_query_url:
drupalvm.dev/simple
drupalvm.dev/big-with-images
In the Purge_query:
drupalvm.dev/simple
drupalvm.dev/big-with-images
But here should be all pages, because the block with the Recent content is on all pages (and we need update all urls in the external cache). But because of the fact that in the logged in state I visited the main page and drupalvm.dev/timka these URLS do not fall into the queue for purging.
Step 3:
Log out.
If visit drupalvm.dev/timka it will be in the Purge_query_url
But Purge_query consist:
drupalvm.dev/simple
drupalvm.dev/big-with-images
As a result:
It seems that a mechanism works only partially.
In the case where there are common blocks, some of the addresses get in the queue for purging. But the edited page and the visited pages before editing (their URLs were removed from the table) will not get into the purge queue.