Failure: 25.8.13 Stable - RegressionTestsRelease / Iceberg (1) - SHOW DATABASES differs when show_data_lake_catalogs_in_system_tables is toggled

[CarlosFelipeOR]

Version: 25.8.13.10194.altinitystable

Description

The Iceberg regression tests fail in show_databases_queries due to an assertion expecting identical SHOW DATABASES output with show_data_lake_catalogs_in_system_tables enabled and disabled.

When the setting is enabled, the Iceberg catalog database appears in the result; when disabled, it does not, causing the assertion to fail.

Query with setting enabled

SET show_data_lake_catalogs_in_system_tables = 1;
SHOW DATABASES;

Result:

INFORMATION_SCHEMA
default
iceberg_database_name
information_schema
system

Query with setting disabled

SET show_data_lake_catalogs_in_system_tables = 0;
SHOW DATABASES;

Result:

INFORMATION_SCHEMA
default
information_schema
system

Analysis

The failure occurs in the Iceberg show_databases_queries scenario, which explicitly sets show_data_lake_catalogs_in_system_tables to both 1 and 0 and asserts that the output of SHOW DATABASES is identical in both cases.

This behavior is related to the upstream issue #89189, which was addressed by PR #89914. That PR ensures that Iceberg / DataLakeCatalog databases are consistently shown in SHOW DATABASES, regardless of the value of show_data_lake_catalogs_in_system_tables.

In the 25.8.13 build, PR #88341 was backported, but its follow-up fix PR #89914 was not. As a result, toggling the setting still affects the output of SHOW DATABASES, causing the test assertion to fail.

Therefore, the failure is not test-related, but due to a missing upstream fix in this release.

Resolution

Backport PR #89914 to the 25.8.13 branch to fully address issue #89189 and ensure that SHOW DATABASES behavior is consistent regardless of the show_data_lake_catalogs_in_system_tables setting.

Verification

Verify the backport of PR #89914 on 25.8 after re-running the Iceberg regression tests:

• 25.8 Stable – backport applied and Iceberg tests re-run
• 25.8 Antalya – backport applied and Iceberg tests re-run

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CI Run

https://github.com/Altinity/ClickHouse/actions/runs/20555519332/job/59039195104

Artifacts and Reports

https://altinity-build-artifacts.s3.amazonaws.com/index.html#PRs/1258/608389689cb3b533aa872e2c3ac50308299070c9/regression/x86_64/with_analyzer/zookeeper/without_thread_fuzzer/iceberg1/

[CarlosFelipeOR]

Analysis and Resolution have been added to this issue.

To finalize this, we are now waiting for the backport of PR #89914, which was requested in the #releases-25_8 Slack channel. Once the backport is available, the Iceberg tests will be re-run to confirm that the issue is resolved.

[CarlosFelipeOR]

After PR #1266 applying the backport, a new Iceberg failure was observed in the show_data_lake_catalogs_in_system_tables scenario.

This failure happened because the default value of show_data_lake_catalogs_in_system_tables differs between upstream 25.8 (default = 1) and Altinity 25.8 Stable (default = 0). The test was assuming a single default value for all 25.8 builds, which is not true after the backports.

The test logic was updated to explicitly handle the 25.8 Altinity Stable case, while preserving the existing expectations for upstream builds.

Commit: 0f9bcf5

[CarlosFelipeOR]

After the previous fix, another Iceberg failure was observed in the show_tables_queries scenario.

This failure was also caused by behavioral differences in 25.8 Altinity builds after the applied backports, where SHOW TABLES is no longer affected by the show_data_lake_catalogs_in_system_tables setting. The test was still expecting an empty result when the setting was disabled, which is no longer valid for this build.

The test logic was updated to treat 25.8 Altinity builds consistently with the newer behavior, and the fix was applied in commit f4c832b

[CarlosFelipeOR]

All regression tests, including the Iceberg suite, are now passing on PR #1266:
https://github.com/Altinity/ClickHouse/actions/runs/20738642453

PR #1266 has been merged successfully.

To fully close this issue, we are now waiting for the same backports to be applied to Antalya 25.8. Once available, the Iceberg tests will be re-run there as well.