dbt adapter conformance¶

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

Every still-failing test falls into one of these categories:

No persistent views. Delta has no view primitive, so a materialized='view' model is a transient DuckDB catalog view, and the tests that swap a model table → view (TestSimpleMaterializationsDuckDB::test_base, changing_relation_type) have nowhere durable to land. Rewriting Delta data on a materialization change is deliberately not done.
Deliberate rejection of silently-divergent merge configs. merge_on_using_columns and a clause action: error have no delta-rs equivalent, so duckrun raises instead of running something else; test_ducklake_valid_single_update stays red on purpose. merge_clauses and merge_update_set_expressions are translated and pass.
delta-rs and DuckDB limits. sync_all_columns needs column drops, which delta-rs cannot do (schema evolution is add-only); QuotingFalse expects a compile error for unquoted identifiers with spaces, which DuckDB permits.

dbt adapter conformance — duckrun¶

┌────────────────────────────────────────────────────────┐
│ ✅ 153 passed   ❌ 4 failed   💥 0 errors   ⏭️ 10 skipped │
│ 167 total · 92% 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
`drop_relation`	`██████████` 100%	3	0	0	3
`empty`	`██████████` 100%	2	0	0	2
`ephemeral`	`██████████` 100%	3	0	0	3
`fast_seed`	`██████████` 100%	4	0	0	4
`get_columns_in_relation`	`██████████` 100%	2	0	0	2
`incremental_microbatch`	`██████████` 100%	14	0	0	14
`simple_snapshot`	`██████████` 100%	10	0	0	10
`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
`utils`	`█████████░` 88%	28	0	4	32
`persist_docs`	`████████░░` 80%	4	0	1	5
`incremental`	`████████░░` 76%	22	2	5	29
`changing_relation_type`	`░░░░░░░░░░` 0%	0	1	0	1
Total	`█████████░` 92%	153	4	10	167

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 (22/29 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 |