Allow configuring the collation of asset name columns

[1fanwang]

Fresh MySQL-compatible installs fail without latin1_general_cs. Airflow uses single-byte collation to fit 1,500-character indexes.

A database setting now controls ORM and migration collations.

Fixes #31373

Testing Done

Tested against TiDB 8.5.1.

Raw logs

$ airflow db migrate
[info] Creating Airflow database tables from the ORM
pymysql.err.OperationalError: (1273, "Unsupported collation when new collation is enabled: 'latin1_general_cs'")

$ AIRFLOW__DATABASE__SQL_ENGINE_COLLATION_FOR_ASSET_NAMES=latin1_bin airflow db migrate
[info] Creating Airflow database tables from the ORM
[info] Running stamp_revision  -> c7f0a5d2e9b4
[info] Database migration done!

$ mysql -N -B -h 127.0.0.1 -P 14000 -u root airflow_custom -e "
  SELECT CONCAT('tables=', COUNT(*))
  FROM information_schema.tables
  WHERE table_schema = 'airflow_custom';
  SELECT CONCAT(table_name, '.', column_name, '=', collation_name)
  FROM information_schema.columns
  WHERE table_schema = 'airflow_custom'
    AND (table_name LIKE 'asset%' OR table_name LIKE 'dag_schedule_asset_%_reference')
    AND column_name IN ('name', 'uri', 'group')
  ORDER BY table_name, ordinal_position"
tables=75
asset.name=latin1_bin
asset.uri=latin1_bin
asset.group=latin1_bin
asset_active.name=latin1_bin
asset_active.uri=latin1_bin
asset_alias.name=latin1_bin
asset_alias.group=latin1_bin
asset_watcher.name=latin1_bin
dag_schedule_asset_name_reference.name=latin1_bin
dag_schedule_asset_uri_reference.uri=latin1_bin

$ AIRFLOW__DATABASE__SQL_ENGINE_COLLATION_FOR_ASSET_NAMES=latin1_bin airflow db migrate --show-sql-only --from-version 2.7.0 --to-version 3.4.0 > migration.sql
$ grep -c latin1_bin migration.sql
14
$ grep -c latin1_general_cs migration.sql
0

$ uv run --project airflow-core pytest airflow-core/tests/unit/models/test_base.py airflow-core/tests/unit/migrations/test_migration_utils.py -k asset_name_collation -q
12 passed, 1 warning

$ uv run --project airflow-core pytest airflow-core/tests/unit/migrations/test_migration_utils.py::test_migration_stairway airflow-core/tests/unit/models/test_asset.py -q
9 passed, 1 warning

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[potiuk]

Hello @1fanwang - thank you for your contributions to Apache Airflow!

The Airflow community has introduced a limit of 5 open pull requests at a time for contributors without write access to the repository. You currently have 34 open pull requests, so - as a one-time step of introducing the limit - we closed the ones where maintainers have not engaged yet:

• Report failure causes and bound infrastructure replacements #66405 - Report failure causes and bound infrastructure replacements
• Honor AirflowFailException raised inside on_retry_callback #66781 - Honor AirflowFailException raised inside on_retry_callback
• Emit OpenTelemetry spans from airflow CLI entry points #66789 - Emit OpenTelemetry spans from airflow CLI entry points
• Preserve sensor start_date when scheduler advances reschedule to queued #66790 - Preserve sensor start_date when scheduler advances reschedule to queued
• Reuse the resumable core for TriggerDagRunOperator's durable wait #68955 - Reuse the resumable core for TriggerDagRunOperator's durable wait
• Let TriggerDagRunOperator own its execution via a new accessor #69135 - Let TriggerDagRunOperator own its execution via a new accessor
• Add resumable_job.reconnect_failure metric for failed reconnects #70653 - Add resumable_job.reconnect_failure metric for failed reconnects
• Allow configuring the collation of asset name columns #71249 - Allow configuring the collation of asset name columns
• Fix task_instance_history downgrade failing under the PyMySQL driver #71258 - Fix task_instance_history downgrade failing under the PyMySQL driver
• Correct the retry_db_transaction docstring about provide_session #71311 - Correct the retry_db_transaction docstring about provide_session
• Show worker pod logs for tasks that failed before writing any log #71566 - Show worker pod logs for tasks that failed before writing any log
• Reconnect Synapse Spark batches on task retry #72368 - Reconnect Synapse Spark batches on task retry
• Reconnect Azure Data Factory pipelines on task retry #72399 - Reconnect Azure Data Factory pipelines on task retry
• Prevent duplicate Anthropic batches on task retry #72400 - Prevent duplicate Anthropic batches on task retry
• Reconnect AWS Batch jobs after worker crashes #72413 - Reconnect AWS Batch jobs after worker crashes
• Reconnect Airbyte sync jobs after task retries #72414 - Reconnect Airbyte sync jobs after task retries
• Reconnect Data Fusion pipelines after task retries #72415 - Reconnect Data Fusion pipelines after task retries
• Prevent duplicate OpenAI batches on task retry #72416 - Prevent duplicate OpenAI batches on task retry
• Recover Dataproc jobs after worker crashes #72417 - Recover Dataproc jobs after worker crashes
• Recover Athena queries after worker crashes #72419 - Recover Athena queries after worker crashes
• Reconnect Cloud Batch jobs on task retry #72420 - Reconnect Cloud Batch jobs on task retry
• Prevent duplicate ECS submissions on task retry #72421 - Prevent duplicate ECS submissions on task retry
• Recover Databricks SQL statements after task retries #72422 - Recover Databricks SQL statements after task retries
• Reconnect dbt Cloud runs after worker crashes #72423 - Reconnect dbt Cloud runs after worker crashes
• Restore missing serialized Dags without a full reparse #72927 - Restore missing serialized Dags without a full reparse
• Report task failure causes without changing retries #73350 - Report task failure causes without changing retries

These pull requests stay open because maintainers are already engaged in them - they count towards your limit:

• Add durable option to TriggerDagRunOperator to reconnect on retry #68936 - Add durable option to TriggerDagRunOperator to reconnect on retry
• Let deferrable tasks reconnect without polling #68952 - Let deferrable tasks reconnect without polling
• Retry transient database errors in the metastore secrets backend #71307 - Retry transient database errors in the metastore secrets backend
• Return each attempt's own URL from operator extra links #71522 - Return each attempt's own URL from operator extra links
• Return 404 instead of 500 when DagRun is missing in Execution API #72907 - Return 404 instead of 500 when DagRun is missing in Execution API
• Edge: Return 404 for missing task logs and emit failed job metrics #72908 - Edge: Return 404 for missing task logs and emit failed job metrics
• Edge: Return 400 instead of 500 on invalid worker version #72925 - Edge: Return 400 instead of 500 on invalid worker version
• Return 404 for task-state writes after a Dag run is deleted #72926 - Return 404 for task-state writes after a Dag run is deleted

This is not a judgement of you or of your changes. We never told contributors before that opening many pull requests at once was a problem, so there is nothing to feel bad about - and nothing is lost: your branches, commits and the review history stay where they are.

What we ask you to do is to make your first prioritization decision: choose which of the pull requests above matter most to you, and reopen them (up to 5 open at a time, including the ones still open) with the "Reopen pull request" button or gh pr reopen <PR_NUMBER> --repo apache/airflow. Reopen the ones you are ready to follow through - keep them rebased, respond to review comments and fix failing checks.

While your pull requests are waiting for review, the most valuable thing you can do is help in other ways - reviewing other contributors' pull requests, helping with issues, and taking part in the discussions on the devlist and Slack.

Why we introduced the limit, what it means for you and how to reopen or restore a pull request is explained in https://github.com/apache/airflow/blob/main/contributing-docs/32_open_pull_request_limit.rst.

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Drafted-by: Claude Code (Opus 5); reviewed by @potiuk before posting