Atnalya 26.6 EXPORT PARTITION with position matching + extra columns in source

[k-morozov]

From 26.3 #2111

Changelog category (leave one):

• New Feature

Changelog entry (a user-readable short description of the changes that goes to CHANGELOG.md):

Added the export_merge_tree_part_schema_mismatch_mode setting. With ignore_extra_source_columns_by_position (default: strict), EXPORT PART/EXPORT PARTITION allows a source table with extra trailing columns — they are simply
ignored instead of failing with NUMBER_OF_COLUMNS_DOESNT_MATCH.

Documentation entry for user-facing changes

...

CI/CD Options

Exclude tests:

• Fast test
• Integration Tests
• Stateless tests
• Stateful tests
• Performance tests
• Aarch64 tests
• All with ASAN
• All with TSAN
• All with MSAN
• All with UBSAN
• All with Coverage
• All Regression
• Disable CI Cache

Regression jobs to run:

• Fast suites (mostly <1h)
• Aggregate Functions (2h)
• Alter (1.5h)
• Benchmark (30m)
• ClickHouse Keeper (1h)
• Iceberg (2h)
• LDAP (1h)
• OAuth (5m)
• Parquet (1.5h)
• RBAC (1.5h)
• SSL Server (1h)
• S3 (2h)
• S3 Export (2h)
• Swarms (30m)
• Tiered Storage (2h)

[github-actions]

Workflow [PR], commit [c162ded]