fixed sort order for mapped task instances

[manipatnam]

order_by=rendered_map_index on the listMapped and listTaskInstances endpoints had a bug:

1. Lexicographic ordering for 10+ mapped instances — the CAST(map_index AS String) fallback produces string comparison: "10" sorts before "2", "20" before "3", etc. A Dag with 12 mapped tasks returned them as 0, 1, 10, 11, 2, 3 … instead of 0, 1, 2, 3 … 10, 11.

closes: #67451

Root cause

SortParam resolved rendered_map_index to a single column for ORDER BY. With a nullable primary column and a string-cast fallback, there was no stable integer secondary key, so UUID ordering determined page membership for tasks without map_index_template.

Fix

Extend SortParam.to_replace to accept list[Column] as a compound sort: a single user-facing sort key expands into multiple ORDER BY columns. Both listMapped and listTaskInstances now map rendered_map_index to [TI._rendered_map_index, TI.map_index],producing:

ORDER BY _rendered_map_index ASC,   -- NULL when no map_index_template
         map_index            ASC,  -- integer, always present
         id                   ASC   -- UUID, absolute tiebreaker

Scenario	Result
No map_index_template (common case)	All _rendered_map_index NULL → tie on key 1 → sorted by integer map_index → 0, 1, 2, 10, 11 …
With map_index_template	Sorted alphabetically by custom label, then map_index for ties
Retried TI (newer UUID, same map_index)	UUID is last tiebreaker only — no longer pushed off the first page

Changes

airflow/api_fastapi/common/parameters.py

• SortParam.__init__ type annotation extended: dict[str, str | Column | list[Column]] | None
• SortParam._resolve() — when a to_replace value is a list, each column is expanded into its own sort entry using the column's ORM
  .key as attr_name, so row_value() resolves it via getattr without any additional lookup.
• SortParam.row_value() — guard updated to skip list-form values (they are already expanded in _resolve()).

airflow/api_fastapi/core_api/routes/public/task_instances.py

• listMapped and listTaskInstances SortParam both gain "rendered_map_index": [TI._rendered_map_index, TI.map_index] in their to_replace dicts.

Tests

• Updated the two rendered_map_index / -rendered_map_index cases in the existing test_mapped_instances_order parametrize to expect numeric order (list(range(100)) / list(range(109, 9, -1))) instead of the previous lexicographic expectations (sorted(range(110), key=str)).
• New test_rendered_map_index_order_with_template: verifies that when all TIs have a custom _rendered_map_index label the sort is alphabetical by label.
• New test_rendered_map_index_order_retried_tis_not_displaced: simulates retries by assigning newer UUIDs to some TIs and verifies all TIs still appear on the first page in map_index order.

---

Was generative AI tooling used to co-author this PR?

• Yes — Claude Code (claude-sonnet-4-6)

Generated-by: Claude Code (claude-sonnet-4-6) following the guidelines

[pierrejeambrun]

Do you have screenshot of before/after to highlight the behavior.

There is also the get_task_instances endpoint that specifies the rendered_map_indexes in the order param, that should probably be also updated.

I think this fixes the part where rendered_map_index is None, but that's actually almost never the case. Unless the dynamic tasks mapping isn't expended yet, rendred_map_index will fallback to the map_index.

[manipatnam]

Tested using the following DAG:

from datetime import datetime

from airflow.decorators import dag, task


@dag(
    dag_id="dynamic_mapped_dag",
    start_date=datetime(2026, 1, 1),
    schedule=None,
    catchup=False,
    tags=["dynamic", "mapped"],
)
def dynamic_mapped_dag():
    @task
    def generate_indexes() -> list[int]:
        return list(range(126))

    @task
    def process(index: int) -> int:
        print(f"Processing map_index={index}")
        return index

    @task(map_index_template="{{ user }}")
    def process_labeled(user: str) -> str:
        print(f"Processing user={user}")
        return user

    process.expand(index=generate_indexes())
    process_labeled.expand(user=["zebra", "apple", "mango", "cherry", "banana"])


dynamic_mapped_dag()

---

Task: process

Before this PR (including #66008 fix)

Default view

When sorted ascending

When sorted descending

---

Using the code in this PR (also includes #66008 fix)

Default behaviour when no filter is applied

When sorted ascending

When sorted descending

Default behaviour when map_index 124 and 123 are retried

---

Task: process_labeled (Nothing changed)

Before this PR (including #66008 fix)

Default view

When sorted ascending

When sorted descending

Default view when map_index cherry and mango are retried

---

Using the code in this PR (also includes #66008 fix)

Default behaviour when no filter is applied

When sorted ascending

When sorted descending

Default behaviour when map_index cherry and mango are retried

[pierrejeambrun]

LGTM thanks.

CI isn't happy some tests need adjustment.

One nit / question and good to go I believe.

Error see comment

[pierrejeambrun]

Pagination isn't working anymore:

Screen.Recording.2026-05-27.at.13.46.50.mov