dbt adapter conformance¶

tests/conformance/ runs the official dbt adapter test suite (dbt-tests-adapter) against duckrun (.github/workflows/cores.yml, conformance job). The card below is published to the job summary and regenerated on every push to main, so it reflects the latest main — which may be ahead of the published PyPI release.

Every still-failing test in the card below falls into one of three categories:

no persistent views — the open Delta format (and deltalake==1.5.0) has no view primitive; a view exists only in some engine's catalog, never on disk. duckrun's durable artifact is always a Delta table, so a materialized='view' model is just a transient DuckDB catalog view, and the tests that swap a model's materialization table → view (TestSimpleMaterializationsDuckDB::test_base, changing_relation_type) have no durable home to land in. Satisfying them would mean rewriting Delta data on a mere materialization change — deliberately not done.
deliberate rejection of silently-divergent merge configs — merge_on_using_columns (and a clause action: error) are dbt-duckdb-specific with no delta-rs equivalent. duckrun raises a clear error rather than accept them and quietly run something else (a silent-divergence data bug), so test_ducklake_valid_single_update stays red on purpose. merge_clauses and merge_update_set_expressions ARE translated onto delta-rs's TableMerger clause list — test_merge_custom_clauses and test_merge_with_set_expressions pass.
delta-rs capability limit — on_schema_change='sync_all_columns' requires dropping columns, which delta-rs can't do (it's add-only), so duckrun's schema evolution is add-only; and QuotingFalse expects a hard compile error for unquoted identifiers with spaces, which DuckDB and delta-rs simply permit.

dbt adapter conformance — duckrun¶

┌───────────────────────────────────────────────────────┐
│ ✅ 149 passed   ❌ 4 failed   💥 0 errors   ⏭️ 5 skipped │
│ 158 total · 94% passing                               │
└───────────────────────────────────────────────────────┘

By suite¶

Suite	Pass rate	✅	❌	⏭️	Total
`aliases`	`██████████` 100%	2	0	0	2
`caching`	`██████████` 100%	2	0	0	2
`concurrency`	`██████████` 100%	2	0	0	2
`constraints`	`██████████` 100%	19	0	0	19
`empty`	`██████████` 100%	2	0	0	2
`ephemeral`	`██████████` 100%	3	0	0	3
`fast_seed`	`██████████` 100%	4	0	0	4
`incremental_microbatch`	`██████████` 100%	14	0	0	14
`simple_snapshot`	`██████████` 100%	9	0	0	9
`store_test_failures`	`██████████` 100%	1	0	0	1
`unit_testing`	`██████████` 100%	5	0	0	5
`unit_testing_incremental`	`██████████` 100%	15	0	0	15
`basic`	`█████████░` 94%	15	1	0	16
`incremental`	`█████████░` 92%	24	2	0	26
`utils`	`█████████░` 88%	28	0	4	32
`persist_docs`	`████████░░` 80%	4	0	1	5
`changing_relation_type`	`░░░░░░░░░░` 0%	0	1	0	1
Total	`█████████░` 94%	149	4	5	158

Incremental / write support¶

Capability		Notes
`materialized='table'` (overwrite)	✅	full rewrite each run (delta_rs overwrite)
first run / `--full-refresh`	✅	overwrites
`append`	✅	append; auto-fenced when the model reads `{{ this }}` (else a blind append); default when no `unique_key`
`merge` (upsert)	✅	update matched + insert new, on `unique_key`; default with `unique_key`
`insert` (insert-only)	✅	insert new keys only (idempotent / dedupe)
`merge_update_columns`	✅	update only the listed columns on match
`merge_exclude_columns`	✅	update every column except the listed ones
`incremental_predicates`	✅	AND-ed into the merge condition (merge strategy)
`merge_update_condition` / `merge_insert_condition`	✅	honored as delta_rs per-clause predicates (gate which rows update / insert)
`on_schema_change='append_new_columns'`	✅	new columns added via delta_rs schema evolution
`on_schema_change='fail'`	✅	raises if the model's columns drift from the table
`partition_by`	✅	Delta partition columns
`on_schema_change='sync_all_columns'`	⚠️	add-only — delta_rs can't drop columns
`delete+insert`	✅	true delete+insert (duplicate-tolerant): delete the matched keys, insert every incoming row, committed as one fenced overwrite pinned to the version read (delta_rs has no two-commit delete+insert)
`microbatch` strategy	✅	per-batch atomic replaceWhere on the `event_time` window (single Delta commit, snapshot-pinned)
`merge_clauses` / `merge_update_set_expressions` / `merge_on_using_columns`	❌	dbt-duckdb-specific, no delta_rs equivalent — rejected with a clear error, never silently ignored
model contracts — column name/type/count	✅	enforced via dbt's `assert_columns_equivalent` preflight before the write
constraints — `not null`	✅	pre-write guard on the staged rows; a null fails the run and leaves the prior table intact
constraints — `check` / `primary_key` / `foreign_key`	❌	not enforceable against a `delta_scan` view; declared but not checked

Not passing — details by suite¶

changing_relation_type — 1 not passing (0/1 pass)

| Outcome | Test | Message | | --- | --- | --- | | ❌ | `TestChangeRelationTypesDuckDB::test_changing_materialization_changes_relation_type` | AssertionError: dbt exit state did not match expected |

incremental — 2 not passing (24/26 pass)

| Outcome | Test | Message | | --- | --- | --- | | ❌ | `TestIncrementalOnSchemaChange::test_run_incremental_sync_all_columns` | dbt_common.exceptions.base.DbtRuntimeError: Runtime Error Binder Error: Referenced column "field2" not found in FROM clause! Candidate bindings: "field1", "fiel | | ❌ | `TestIncrementalOnSchemaChangeQuotingFalse::test__handle_identifier_quoting_config_false` | AssertionError: dbt exit state did not match expected |

basic — 1 not passing (15/16 pass)

| Outcome | Test | Message | | --- | --- | --- | | ❌ | `TestSimpleMaterializationsDuckDB::test_base` | AssertionError: dbt exit state did not match expected |