[MAINTENANCE] Use the upstream sqlalchemy-redshift dialect instead of the GX fork

[joshua-stauffer]

Summary

sqlalchemy-redshift 1.0.0 (released 2026-04-28) migrated to SQLAlchemy 2 and Python 3.10+ — the reason the GX fork was created in the first place. This drops gx-sqlalchemy-redshift in favor of upstream.

The fork is 15 commits ahead / 40 behind upstream main, and its substantive changes are the SQLAlchemy 2 requirement, pypi repackaging, and pkg_resources removal. Upstream 1.0.0 rewrote dialect.py far more thoroughly, so its migration supersedes the fork's. Last fork push was 2026-02-03.

No library code changes are required. Upstream publishes the same sqlalchemy_redshift import namespace and exports every symbol great_expectations/compatibility/aws.py imports.

A latent bug this also fixes

setup.py listed redshift in sqla1x_only_keys, so the extra carried sqlalchemy<2.0.0:

BEFORE redshift:    ['psycopg2-binary>=2.7.6', 'sqlalchemy-redshift>=0.8.8', 'sqlalchemy<2.0.0']
AFTER  redshift:    ['psycopg2-binary>=2.7.6', 'sqlalchemy-redshift>=1.0.0', 'sqlalchemy>=1.4.0']

That constraint pinned sqlalchemy-redshift back to 0.8.14 (April 2023) regardless of the declared floor, so pip install 'great_expectations[redshift]' has been silently installing a three-year-old dialect. Related fallout was already handled once in #11857.

Backward compatibility

pip install 'great_expectations[gx-redshift]' is a published, documented command, so the extra is kept as a deprecated alias that resolves identically to redshift. Verified:

+ sqlalchemy==2.0.51
+ sqlalchemy-redshift==1.0.0

Its requirements file duplicates requirements-dev-redshift.txt rather than using --requirement, because parse_requirements in setup.py doesn't resolve file references — it would emit the literal --requirement ... string as a requirement. test_deprecated_gx_redshift_extra_matches_redshift keeps the duplicate honest.

Worth flagging for reviewers: pip has no deprecation mechanism for extras, so there's no warning we can emit. The signal only reaches people reading docs, not people running a pinned install command. The eventual removal should get its own major-version callout rather than riding in quietly.

Changes

File	Change
setup.py	redshift moved from sqla1x_only_keys to sqla_keys; gx-redshift marked as a deprecated alias
reqs/requirements-dev-redshift.txt	floor raised to >=1.0.0
reqs/requirements-dev-gx-redshift.txt	now the upstream dialect, documented as a deprecated alias
reqs/requirements-dev-sqlalchemy.txt	points at the canonical -redshift file
.github/workflows/ci.yml	redshift matrix uses the redshift marker (was gx-redshift, with redshift commented out)
.github/workflows/data_source_cleanup.yml	invoke deps -m redshift
tests/test_packaging.py	retargeted at the canonical file; added the alias sync guard
docs/.../_sql.md, _sql_dialect_installation_commands.md	one Redshift row; the stale "GX fork with SQLAlchemy 2.0" admonition replaced with the deprecation note

tasks.py needed no functional change — a redshift entry already existed in MARKER_DEPENDENCY_MAP pointing at the right file, and both marker names resolve to the pytest marker redshift.

Verification

Run locally:

• tests/test_packaging.py + tests/test_markers.py — 4 passed.
• Installed [redshift] from this branch into a clean env: resolves sqlalchemy 2.0.51 / sqlalchemy-redshift 1.0.0, gx-sqlalchemy-redshift absent. All 12 symbols in compatibility/aws.py import; redshift+psycopg2:// resolves to sqlalchemy_redshift.dialect.RedshiftDialect_psycopg2.
• [gx-redshift] dry-run resolves identically.
• The new sync assertion was mutation-tested — it fails when either file's dep set or version specifier drifts. (The pre-existing union-equality assertions in test_requirements_files do not catch drift in these files, since a change lands on both sides of the equality; that's why the alias needed its own guard.)
• ruff check / ruff format --check clean; both workflow YAMLs parse.

Not verifiable locally: the actual Redshift integration tests need credentials and only run in the redshift CI job, which requires a non-draft PR. Leaving this as draft until that job is green — that's the real gate on this change, since it's the only thing that exercises the upstream dialect against a live cluster.

Out of scope

The fork's repo and its gx-sqlalchemy-redshift PyPI package remain published as-is; retiring those is separate from this change.

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