fix: preserve newlines in Spark/Databricks compiled_code (create Spark temp tables with an explicit file format)

[haritamar]

Summary

Since 0.23.0 (#946), spark__escape_special_chars replaced \n/\r with spaces. dbt-databricks dispatches databricks → spark → default, so every Databricks customer's compiled_code in dbt_run_results was flattened to one line; any model starting with a -- comment then fails to parse in Elementary Cloud column-level lineage (ParseError: No expression was parsed from '-- ...'), and inline -- comments silently truncate lineage.

#946 attributed the OSS Spark row corruption to INSERT VALUES not supporting \n escapes. That was a misdiagnosis. The actual cause is how the intermediate table is created:

-- spark__edr_get_create_table_as_sql (non-temporary, used for artifact staging on dbt-spark)
create table <tmp> as select ... where 1=0     -- no USING

With Spark 3's default spark.sql.legacy.createHiveTableByDefault=true this is a Hive TEXTFILE table (LazySimpleSerDe/TextInputFormat, confirmed via describe extended). A text serde cannot hold a newline inside a value, so every escaped \n splits a row on read (the 37-tuple insert → 55 rows). The same insert into a using parquet/using delta table round-trips newlines correctly.

Fix (root cause, not a workaround):

- create table {{ relation }} as {{ sql_query }}
+ create table {{ relation }} using {{ elementary.get_config_var("spark_file_format") }} as {{ sql_query }}

with a new spark__get_default_config (spark_file_format: parquet, dbt-spark's own default; fabricspark delegates). spark__escape_special_chars now flattens newlines only when spark_file_format == "hive" (the one format that can't hold them) and otherwise delegates to default__escape_special_chars; databricks__escape_special_chars is removed so dbt-databricks uses the default \\n escaping. This also covers customers running the dbt-spark adapter against Databricks (target type spark), which a Databricks-only override would have missed.

Regression test: test_compiled_code_preserves_newlines runs a model whose compiled SQL starts with a -- comment line (models/one.sql) and asserts the persisted compiled_code keeps that comment on its own line with the query after it. Runs on all targets incl. spark/fabricspark; skipped on dbt-fusion, which currently writes no compiled_code rows in this path.

Verified locally on the Docker Spark Thrift setup: full test_artifacts.py (16 passed incl. test_artifacts_collection_in_multiple_row_batches and the new test), insert-rows/long-string tests, dbt parse --target spark, pre-commit. Also checked spark_file_format: hive one-off: multi-batch test still 37/37 (flattening protects the text table), newline test fails there as expected.

Note for Cloud: affected customers need the package upgrade + a dbt run; flattened models will recompute automatically since the compiled-code hash changes.

Link to Devin session: https://app.devin.ai/sessions/7c9a2683e2d446428a12decba40a004b
Open in Devin Desktop: https://app.devin.ai/desktop/session/7c9a2683e2d446428a12decba40a004b?variant=devin
Requested by: @haritamar

Summary by CodeRabbit

• New Features

  • Added Spark and Fabric Spark defaults, including Parquet as the default Spark file format.
  • Spark-created non-temporary tables now explicitly use the configured file format.

• Bug Fixes

  • Fixed compiled SQL formatting so leading comments and newline characters are preserved.
  • Expanded compiled-code validation for Spark and Fabric Spark.
  • Standardized special-character escaping across Spark-based adapters.

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👋 @haritamar
Thank you for raising your pull request.
Please make sure to add tests and document all user-facing changes.
You can do this by editing the docs files in the elementary repository.

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📝 Walkthrough

Walkthrough

Changes

Compiled SQL newline preservation

Layer / File(s)	Summary
Preserve and validate compiled SQL newlines macros/utils/table_operations/insert_rows.sql, integration_tests/dbt_project/models/one.sql, integration_tests/tests/test_dbt_artifacts/test_artifacts.py	The Databricks escaping macro preserves newline characters. The test model includes a leading comment. The integration test verifies comment placement and the select 1 statement across supported adapters.

Estimated code review effort: 2 (Simple) | ~10 minutes

Merge Risk: 🟡 Moderate · up to 4a0f3

The newline-preservation change improves Spark compiled SQL handling, but the artifact integration test may fail when compiled_code is NULL. Resolve or guard that case before merging.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 3 functions across 1 files. (1 skipped: 1 …	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly describes the main change: preserving newlines in Spark and Databricks compiled_code by using an explicit Spark table file format.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 3 functions across 1 files. (1 skipped: 1 unsupported.)

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Inline comments:
In `@integration_tests/tests/test_dbt_artifacts/test_artifacts.py`:
- Line 220: Guard nullable compiled_code results in the dbt_run_results
query/processing loop before calling lstrip(), either by asserting the fetched
value is not None or by excluding null rows in the query. Preserve processing of
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