chore(ibis-server): Fix real type & nested composite type mapping for Trino engine

[okayhooni]

• Add real type mapping to RustWrenEngineColumnType.REAL in Trino type mapping
• Preserve original type string for complex/parametric types (array, map, row), consistent with BigQuery and Databricks implementations
• Normalize type string before regex substitution to avoid redundant .lower() call

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Summary by CodeRabbit

Bug Fixes

• Enhanced Trino data type handling with support for the "real" type and improved processing of complex types (arrays, maps, rows).
• Optimized type normalization for more consistent type mapping and fewer unmapped type warnings.

[coderabbitai]

📝 Walkthrough

Walkthrough

Added "real" type mapping to TRINO_TYPE_MAPPING and refactored TrinoMetadata._transform_column_type to normalize lowercased input types and special-case complex parametric types (array, map, row) to return original data_type unchanged.

Changes

Cohort / File(s)	Summary
Type Mapping and Normalization ibis-server/app/model/metadata/trino.py	Added "real" type mapping to TRINO_TYPE_MAPPING; refactored _transform_column_type to normalize lowercased types, special-case complex parametric types, and remove parameters from normalized values before mapping lookup.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~12 minutes

Possibly related PRs

• fix(ibis-server): fix Trino timestamp type mapping for timestamp with time zone #1442: Modifies TRINO_TYPE_MAPPING entries in the same file to adjust Trino-to-RustWrenEngineColumnType mappings.
• fix(ibis): fix ClickHouse Decimal/Numeric and Nullable Type Mapping #1423: Refactors _transform_column_type logic across multiple connectors to normalize parameterized types and extend type mapping dictionaries.
• chore(ibis): refactor the type mapping table #1302: Introduces and updates TRINO_TYPE_MAPPING while refactoring TrinoMetadata._transform_column_type with similar normalization patterns.

Suggested labels

ibis, python

Suggested reviewers

• goldmedal
• douenergy

Poem

A real type mapping blooms, 🌱
Types dance through lowercase streams,
Complex cases shine so bright,
Parameters fade from sight,
Data flows just right! ✨

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.
Title check	✅ Passed	The title clearly describes the main changes: fixing type mapping for both the 'real' type and nested composite types in the Trino engine, which aligns with the PR objectives.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

📝 Coding Plan

• Generate coding plan for human review comments

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[coderabbitai]

Caution

Some comments are outside the diff and can’t be posted inline due to platform limitations.

⚠️ Outside diff range comments (1)

ibis-server/app/model/metadata/trino.py (1)

143-157: ⚠️ Potential issue | 🟡 Minor

Return type annotation does not match implementation.

Line 143 declares RustWrenEngineColumnType, but the method also returns str at line 157 for complex types. Update the signature and docstring to use a union type.

Note: The comment references "Databricks implementations" for consistency, but Databricks does not return raw strings—it always returns RustWrenEngineColumnType values. BigQuery correctly uses the union type approach shown in the proposed fix.

🔧 Proposed fix

-    def _transform_column_type(self, data_type: str) -> RustWrenEngineColumnType:
+    def _transform_column_type(self, data_type: str) -> str | RustWrenEngineColumnType:
         """Transform Trino data type to RustWrenEngineColumnType.
 
         Args:
             data_type: The Trino data type string
 
         Returns:
-            The corresponding RustWrenEngineColumnType
+            The corresponding RustWrenEngineColumnType or original string for
+            complex types

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In `@ibis-server/app/model/metadata/trino.py` around lines 143 - 157, The
_transform_column_type method currently declares a return type of
RustWrenEngineColumnType but returns raw strings for complex/parametric types;
change the signature to return a union (RustWrenEngineColumnType | str) and
update the docstring to state it may return either a RustWrenEngineColumnType or
the original type string for complex types (preserve behavior for
array/map/row). Ensure any needed typing imports (e.g., from typing import Union
or using PEP 604 syntax) are added and keep the logic in _transform_column_type
unchanged except for the annotated return type and docstring.

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Outside diff comments:
In `@ibis-server/app/model/metadata/trino.py`:
- Around line 143-157: The _transform_column_type method currently declares a
return type of RustWrenEngineColumnType but returns raw strings for
complex/parametric types; change the signature to return a union
(RustWrenEngineColumnType | str) and update the docstring to state it may return
either a RustWrenEngineColumnType or the original type string for complex types
(preserve behavior for array/map/row). Ensure any needed typing imports (e.g.,
from typing import Union or using PEP 604 syntax) are added and keep the logic
in _transform_column_type unchanged except for the annotated return type and
docstring.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: b9f42d23-7e7a-4c8c-9dd5-3958e995a7f4

📥 Commits

Reviewing files that changed from the base of the PR and between 642b7ee and 9cb147c.

📒 Files selected for processing (1)

• ibis-server/app/model/metadata/trino.py

[goldmedal]

Thanks @okayhooni 👍