Support for query splitting to Replica in core

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Created on 29 May 2019, over 5 years ago

Updated 3 September 2024, 5 days ago

I understand how to configure the $database['default']['replica'][] settings so that I can point to 1..N replica servers.

I do not understand how to get anything but my custom-written queries to leverage the Replica servers.

This seems to me like a core feature to supporting multiple databases in core, but I see no clear path to handling this logic, nor do I see a clear place to override this

I've even tried

 if (!isset($options['target']) && stripos($query, 'SELECT') === 0) {
        $options['target'] = 'replica';
      }
      return parent::query($query, $args, $options);

in
Drupal\Core\Database\Driver\mysql\Connection function query(
but whatever other processes are involved with loading any page in Drupal appear to mark the replica as invalid, so I never actually have any queries that execute against the replica in this scenario.

This seems to me like a core scaling issue for Drupal, so I'm not clear on if I'm just misunderstanding how this is supposed to work, or if the only recommendation is to use an external process such as proxySQL or other mechanism to split read/write queries across master/slave (primary/replica)

✨ Feature request

Status

Needs work

Version

11.0 🔥

Component

MySQL driver →

Last updated 5 days ago

Maintained by
🇺🇸United States @David Strauss

Created by

🇺🇸United States craigmc

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needs-review-queue-bot
The Needs Review Queue Bot → tested this issue. It either no longer applies to Drupal core, or fails the Drupal core commit checks. Therefore, this issue status is now "Needs work".

Apart from a re-roll or rebase, this issue may need more work to address feedback in the issue or MR comments. To progress an issue, incorporate this feedback as part of the process of updating the issue. This helps other contributors to know what is outstanding.

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Environment: PHP 8.1 & MariaDB 10.3.22
last update 12 months ago
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Environment: PHP 8.1 & MySQL 8
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Environment: PHP 8.1 & MySQL 8
last update 12 months ago
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Comment 10 months ago →
🇯🇴Jordan Anas_maw
This is a very important issue, especially for high-traffic websites.
Comment 5 days ago →
🇪🇪Estonia hkirsman
+1

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