setup:upgrade is changing indexer mode to `save` from `schedule` slowing it down immensely

[ioweb-gr]

I have a fairly large catalog on a website and I've noticed that sometimes setup:upgrade takes a very very long time to complete. More than 30 minutes.
It's not always occuring which makes it hard to track but by carefully examining what is happening I noticed that the command is dropping and recreating the database triggers when the indexers are set on scheduled mode. However with the indexers on save mode, the backend takes a very long time to save products and especially categories.

So our only option on big catalogs is to use the indexers on schedule mode.

By examining further I went and forced a check on the mview_state table to see what script is changing the indexer mode during setup:upgrade and so the command threw an exception as expected when executing the following query

UPDATE `mview_state` SET `view_id` = ?, `mode` = ?, `status` = ?, `updated` = '2021-06-30 05:57:46', `version_id` = ? WHERE (state_id=5)

View.php:225, Magento\Framework\Mview\View->unsubscribe()
TriggerCleaner.php:63, Magento\Framework\Mview\TriggerCleaner->removeTriggers()
Installer.php:1726, Magento\Setup\Model\Installer->removeUnusedTriggers()
UpgradeCommand.php:145, Magento\Setup\Console\Command\UpgradeCommand->execute()
Command.php:255, Magento\Setup\Console\Command\UpgradeCommand->run()
Application.php:1009, Magento\Framework\Console\Cli->doRunCommand()
Application.php:273, Magento\Framework\Console\Cli->doRun()
Cli.php:115, Magento\Framework\Console\Cli->doRun()
Application.php:149, Magento\Framework\Console\Cli->run()
magento:36, {main}()

Then I was able to see that the functions
\Magento\Framework\Mview\View::unsubscribe
\Magento\Framework\Mview\View::subscribe

Are executed for all indexers regardless, which will trigger dropping and re-adding the database triggers.

However dropping a trigger and recreating in a fairly large database is taking a long time to complete causing significant downtime.

It seems I'm not the only one facing this issue https://magento.stackexchange.com/questions/330245/magento-2-indexers-sometimes-switchon-their-own-to-update-on-save-when-config

Preconditions (*)

1. 2.4.1

Steps to reproduce (*)

1. A fairly large catalog with lots of categories (over 5000) and products (over 60k with over 200 attributes)
2. The indexers set on schedule mode.
3. Execute setup:upgrade

Expected result (*)

1. I expect that setup:upgrade finishes fast and doesn't recreate the triggers if it's not needed. If the trigger exists, it shouldn't drop and recreate it. Only If it does not exist should it create it.
2. It should never change the mode from schedule to save. The user has put it for a reason there

Actual result (*)

1. setup:upgrade is always recreating the triggers causing huge downtime during the command execution
2. sometimes the indexers never revert back to the scheduled mode and stay on save mode

Additional Information

• Confirmation note, AC, and suggested approach setup:upgrade is changing indexer mode to save from schedule slowing it down immensely #33386 (comment)

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[m2-assistant]

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[ioweb-gr]

I'm not able to test this on the demo instance.

[m2-assistant]

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[ioweb-gr]

Let me add more info here. I tracked down this post

https://maxchadwick.xyz/blog/lessons-learned-during-a-recent-magento-2-deploy

It seems that during operations which lock the tables, dropping the trigger or creating it has to actually wait for all database locks to disappear.

Looking further into the process I noticed that in my case it was trying to build the catalog price replica tables for the indexes which were locking the tables like this

 DELETE FROM `catalogrule_product_price_replica` WHERE (product_id NOT IN ((SELECT `crp`.`product_id` FROM `catalogrule_product_price`

Causing a lot of queries to wait during setup:upgrade making the downtime extremely high. Unfortunately even if you build the files in a different server the setup:upgrade procedure has to run on the production.

This should never ever happen and cause such unpredictable downtimes

This is what the end result in mytop looks like in such cases

[onlinebizsoft]

I think I have same issue. Will track this behavior and see

[ioweb-gr]

I've seen it happen in 3 installations on 3 different servers and now before setup:upgrade I make sure all indexers are green to avoid the issue. I will report back if this stops occuring like this but it would be great if it can be verified

[ioweb-gr]

Just an update, while following this practice the downtimes have reduced significantly because the locks are staying for a smaller period. The issue still persists but is minified like this.

Basically I can verify that if the indexers are running on scheduled mode, the issue can happen with setup:upgrade if they have items in the backlog

[m2-assistant]

Hi @engcom-Delta. Thank you for working on this issue.
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[engcom-Delta]

Hi @ioweb-gr
it works fine on Magento 2.4-develop instance, I would request to try once again & confirm .Hence added the label ''Needs update'

Thanks