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Massive concurrent inserts on a node with super_read_only enabled can bypass read only settings

Description

I cannot repeat this on PXC 8.0.33 but I was able to reproduce this on PXC 8.0.30 and PXC 8.0.32.

On one node, create this table and then enable super_read_only:

 

Then, on mysqlslap, run inserts concurrently on this table:

At first, you will see these messages that it's not permitted to insert on this node:

However, after a short while the errors stop spawning and the table gets populated:

From here on, you can also perform your own inserts even if super_read_only is still enabled:

 

 

 

 

 

 

 

 

Environment

None

AFFECTED CS IDs

CS0038757

Activity

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Kamil Holubicki September 12, 2023 at 8:22 AM

I was able to reproduce it locally on 8.0.32.

I confirm that the issue was fixed in 8.0.33. The fix was done by the above-mentioned commit https://github.com/percona/percona-xtradb-cluster/commit/d780c6e01778a0e1037399c7733e68b1c1128524

The issue was that read_only variable was silently/internally modified (set to true) for a short period of time during query execution.

Kamil Holubicki September 11, 2023 at 9:00 AM

AWS instance, Ubuntu 22.04

Checked on versions 8.0.30 and 8.0.32 (from Percona Distribution for PXC)

Setup with 1 node, steps as above.

Not reproducible.

Venkatesh Prasad September 11, 2023 at 7:20 AM

Done

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Yes

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Created September 10, 2023 at 4:53 AM
Updated March 6, 2024 at 8:36 PM
Resolved September 12, 2023 at 8:22 AM