MDEV-37494 Diagnostics_area does not always contain apply error info #4263
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ayurchen
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It appears that some error conditions don't store error information in the Diagnostics_area. For example when table_def::compatible_with() check fails error message is stored in Relay_log_info instead. This results in optimistically identical votes and zero error buffer size breaks wsrep-lib logic as it relies on error buffer size to decide whether voting took place. To account for this, first try to obtain error info from Diagnostics_area, then fallback to Relay_log_info. If that fails use some "random" data to distinguish this condition from success in production.
janlindstrom
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It appears that some error conditions don't store error information in the Diagnostics_area. For example when table_def::compatible_with() check fails error message is stored in Relay_log_info instead. This results in optimistically identical votes and zero error buffer size breaks wsrep-lib logic as it relies on error buffer size to decide whether voting took place.
To account for this, first try to obtain error info from Diagnostics_area, then fallback to Relay_log_info. If that fails use some "random" data to distinguish this condition from success in production.
MTR test supplied
Description
TODO: fill description here
Release Notes
TODO: What should the release notes say about this change?
Include any changed system variables, status variables or behaviour. Optionally list any https://mariadb.com/kb/ pages that need changing.
How can this PR be tested?
TODO: modify the automated test suite to verify that the PR causes MariaDB to behave as intended.
Consult the documentation on "Writing good test cases".
If the changes are not amenable to automated testing, please explain why not and carefully describe how to test manually.
Basing the PR against the correct MariaDB version
mainbranch.PR quality check