fix: preserve typmod for extension types in column type resolution (#295)

[tianzhou]

Summary

• pgvector types with dimensions (e.g., vector(384), halfvec(384)) were losing their typmod during schema inspection because the resolved_type query only returned dt.typname for non-pg_catalog base types
• Now extracts the typmod portion from format_type(atttypid, atttypmod) using a POSIX regex and appends it to the type name, preserving dimensions like vector(384) while maintaining existing schema qualification logic

Fixes #295

Test plan

• Full test suite passes (go test ./...) — all packages green
• Cross-schema extension type test (add_column_cross_schema_custom_type) passes — validates fix doesn't break existing citext/hstore handling
• Manual validation with pgvector: create table with halfvec(384) column and HNSW index, verify pgschema plan preserves dimensions

🤖 Generated with Claude Code

[greptile-apps]

Greptile Summary

Fixed pgvector dimension loss by extracting typmod from format_type() for non-pg_catalog base types.

• Modified column type resolution query to preserve type modifiers (e.g., vector(384)) for extension types
• Uses POSIX regex '\([^)]*\)' to extract typmod portion from format_type(atttypid, atttypmod)
• Applied to both same-schema and cross-schema extension type cases
• Maintains existing behavior for pg_catalog types (varchar, numeric, etc.) which use separate character_maximum_length and numeric_precision fields
• Generated Go code correctly reflects the SQL changes

Confidence Score: 5/5

• This PR is safe to merge with minimal risk
• The change is surgical and well-targeted: it only modifies the type resolution logic for non-pg_catalog base types to preserve typmod. The regex pattern is simple and correct. Standard PostgreSQL types remain unchanged. The fix has been validated by existing test suite passing, and the generated Go code correctly reflects the SQL changes.
• No files require special attention

Important Files Changed

Filename	Overview
ir/queries/queries.sql	Added typmod preservation for extension types using format_type() and regex extraction
ir/queries/queries.sql.go	Generated Go code correctly reflects SQL query changes for typmod preservation

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[Column Type Resolution] --> B{Type Category?}
    B -->|Domain/Enum/Composite| C[Use dt.typname with schema qualification]
    B -->|Array Base Type| D["Use et.typname + [] with schema qualification"]
    B -->|Non-Array Base Type| E{Schema Location?}
    E -->|pg_catalog| F["Use c.udt_name (Standard types handled separately)"]
    E -->|Same as table schema| G["dt.typname + extract typmod (Preserves vector(384))"]
    E -->|Different schema| H["schema.dt.typname + extract typmod (Preserves dimensions)"]
    G --> I["Typmod Extraction: substring(format_type FROM '([^)]*)')"]
    H --> I
    I --> J["Result: vector(384) or halfvec(384)"]
    F --> K["Result: varchar or numeric (Dimensions stored in separate fields)"]

Loading

_{Last reviewed commit: 73f0244}

[Copilot]

Pull request overview

This pull request fixes issue #295 where pgvector extension types with dimensions (e.g., vector(384), halfvec(384)) were losing their type modifiers (typmod) during schema inspection. The root cause was that the column type resolution query only returned the base type name (dt.typname) for non-pg_catalog types, without including the typmod information.

Changes:

• Modified SQL queries to extract typmod from format_type(atttypid, atttypmod) using a POSIX regex pattern and append it to extension type names
• Applied the fix consistently to both GetColumns and GetColumnsForSchema queries
• Preserved existing schema qualification logic while adding typmod support for extension types

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
ir/queries/queries.sql	Updated column type resolution logic in two queries (GetColumns and GetColumnsForSchema) to extract and preserve typmod for extension types using format_type() and regex extraction
ir/queries/queries.sql.go	Generated Go code from the updated SQL queries (auto-generated by sqlc)

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.