Potential Indexer Performance issue for large catalogs - Locking Entire CL table to identity the latest version to be processed

[senthilengg]

Summary

Retrieving the last id with Order By version_id DESC may cause performance issues when the *_cl table piled up with lot of rows and quietly possible for stores with large catalogs

magento2/lib/internal/Magento/Framework/Mview/View/Changelog.php

Line 315 in 410b59d

$select = $this->connection->select()->from($changelogTableName)->order('version_id DESC')->limit(1);

The performance degrade can be moderate to severe based on the number of rows present in cl table.

Examples

Insert few hundred thousand to million rows in CL table and run the query ever minute

Order BY DESC with Limit as per Mysql will be slow

Proposed solution

Since its always run in batches the version id can be manipulated easily

magento2/lib/internal/Magento/Framework/Mview/View.php

Line 315 in 410b59d

$batchSize = isset($this->changelogBatchSize[$this->getChangelog()->getViewId()])

$currentVersionId = $lastVersionId + $batchSize;

Above math can help avoid locking the entire table and the indexer will get updated in a responsive fashion than waiting for the entire rows to complete.

If 100,000 rows in CL then currently indexer status will not get updated until 100K complete in 20 batches assuming per batch 5000 but with the above proposed change it will get update for every batch.

Benefits

1. More responsive indexer status

Admin panel shows actual progress instead of freezing for minutes & sometime for hours.

2. Less DB locking and faster concurrency

Frequent state updates reduce long-running locks.

3. Improved fault tolerance

If the process stops after N batches, next run resumes from version_id N.

4. Better observability and diagnosability

Logs and monitoring tools can see actual batch progression.

Release note

No response

Triage and priority

• Severity: S0 - Affects critical data or functionality and leaves users without workaround.
• Severity: S1 - Affects critical data or functionality and forces users to employ a workaround.
• Severity: S2 - Affects non-critical data or functionality and forces users to employ a workaround.
• Severity: S3 - Affects non-critical data or functionality and does not force users to employ a workaround.
• Severity: S4 - Affects aesthetics, professional look and feel, “quality” or “usability”.

[m2-assistant]

Hi @senthilengg. Thank you for your report.
To speed up processing of this issue, make sure that the issue is reproducible on the vanilla Magento instance following Steps to reproduce.

• For more details, review the Magento Contributor Assistant documentation.
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