fix: preserve INCLUDE columns on CREATE INDEX (#385)

[tianzhou]

Summary

• Index INCLUDE columns were being merged into regular indexed columns because the inspector used indnatts (total columns) instead of indnkeyatts (key columns only)
• Added IncludeColumns field to Index IR struct and updated the SQL query to separately extract include columns from positions indnkeyatts+1 through indnatts
• Updated diff generation to emit INCLUDE (...) clause and structural equality comparison

Fixes #385

Test plan

• Added INCLUDE index test case to existing testdata/diff/create_index/add_index/
• Run: PGSCHEMA_TEST_FILTER="create_index/" go test -v ./cmd -run TestPlanAndApply
• All 150+ diff tests pass with no regressions

🤖 Generated with Claude Code

[greptile-apps]

Greptile Summary

This PR fixes a bug where index INCLUDE columns were being merged into the regular key-column list because the inspector iterated up to indnatts (total columns) rather than indnkeyatts (key columns only). The fix adds an IncludeColumns []string field to the Index IR struct, updates the SQL query to extract the two sets separately, emits the INCLUDE (...) clause in the correct PostgreSQL syntax position, and extends indexesStructurallyEqual to compare the new field.

Confidence Score: 5/5

Safe to merge — the fix is correct and well-tested with no blocking issues.

All findings are P2 (unused NumKeyColumns field in sqlc-generated code, consistent with the pre-existing unused NumColumns). The core bug fix correctly uses indnkeyatts vs indnatts to separate key and INCLUDE columns, the generated SQL clause ordering is valid PostgreSQL syntax (INCLUDE before NULLS NOT DISTINCT and WHERE), and the structural-equality comparison handles the ordered nature of INCLUDE columns correctly.

No files require special attention.

Important Files Changed

Filename	Overview
ir/queries/queries.sql	Correctly splits key columns (1..indnkeyatts) from INCLUDE columns (indnkeyatts+1..indnatts); adds num_key_columns which is unused in Go code
ir/queries/queries.sql.go	sqlc-generated: adds NumKeyColumns and IncludeColumns with scan order matching SELECT list; NumKeyColumns unused
ir/ir.go	Adds IncludeColumns []string to Index struct with omitempty json tag
ir/inspector.go	Assigns indexRow.IncludeColumns to Index struct; column-building loop unchanged since it iterates ColumnDefinitions only
internal/diff/index.go	Emits INCLUDE (...) after key-column list, before NULLS NOT DISTINCT and WHERE — correct PostgreSQL syntax order
internal/diff/table.go	Extends indexesStructurallyEqual with ordered positional comparison of IncludeColumns
testdata/diff/create_index/add_index/new.sql	Adds INCLUDE index test fixture
testdata/diff/create_index/add_index/diff.sql	Expected diff output includes correct INCLUDE clause
testdata/diff/create_index/add_index/plan.json	Plan JSON updated with new index entry
testdata/diff/create_index/add_index/plan.sql	Plan SQL updated with INCLUDE index
testdata/diff/create_index/add_index/plan.txt	Plan text output updated

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[pg_index row] --> B{indnkeyatts vs indnatts}
    B -->|generate_series 1..indnkeyatts| C[column_definitions
column_directions
column_opclasses]
    B -->|generate_series indnkeyatts+1..indnatts| D[include_columns]
    C --> E[Index.Columns]
    D --> F[Index.IncludeColumns]
    E --> G[generateIndexSQLWithName]
    F --> G
    G --> H["CREATE INDEX ... (key_cols)\nINCLUDE (include_cols)\n[NULLS NOT DISTINCT] [WHERE ...];"]
    E --> I[indexesStructurallyEqual]
    F --> I
    I -->|equal| J[no-op]
    I -->|differs| K[DROP + CREATE]

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_{Reviews (1): Last reviewed commit: "fix: preserve INCLUDE columns on CREATE ..." | Re-trigger Greptile}

[greptile-apps]

Unused NumKeyColumns field

NumKeyColumns is scanned from the database but never read anywhere in inspector.go — column counts are already derived implicitly from the lengths of ColumnDefinitions and IncludeColumns. The pre-existing NumColumns field had the same issue before this PR. Both fields could be removed from the query, struct, and scan to reduce noise, but they're harmless as-is.

[tianzhou]

Acknowledged — both NumKeyColumns and NumColumns are unused in Go code (column counts come from array lengths). This is a pre-existing pattern; removing them would be unrelated cleanup. Keeping them harmless and consistent with the SQL query structure.

[Copilot]

Pull request overview

Fixes schema inspection and diff/DDL generation so Postgres index INCLUDE columns are preserved (instead of being incorrectly merged into key columns), addressing issue #385.

Changes:

• Update index inspection query to treat indnkeyatts as the key-column count and separately extract INCLUDE columns from indnkeyatts+1..indnatts.
• Extend the IR index model with IncludeColumns, and update diff structural equality + SQL generation to emit INCLUDE (...).
• Add/update a regression test case under testdata/diff/create_index/add_index/ to cover CREATE INDEX with INCLUDE.

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
ir/queries/queries.sql	Fixes index column extraction by separating key vs INCLUDE columns using indnkeyatts / indnatts.
ir/queries/queries.sql.go	Regenerates/updates sqlc output to include new query fields and scanning for INCLUDE columns.
ir/ir.go	Adds IncludeColumns to the Index IR struct for non-key stored columns.
ir/inspector.go	Populates Index.IncludeColumns from query results during inspection.
internal/diff/index.go	Emits INCLUDE (...) clause in generated CREATE INDEX SQL when applicable.
internal/diff/table.go	Includes IncludeColumns in indexesStructurallyEqual to detect structural changes correctly.
testdata/diff/create_index/add_index/new.sql	Adds a desired-state index containing INCLUDE (name) for regression coverage.
testdata/diff/create_index/add_index/plan.txt	Updates expected plan summary/DDL to include the INCLUDE index.
testdata/diff/create_index/add_index/plan.sql	Updates expected plan SQL output for INCLUDE clause.
testdata/diff/create_index/add_index/plan.json	Updates expected plan JSON step for the INCLUDE index.
testdata/diff/create_index/add_index/diff.sql	Updates expected diff SQL to include INCLUDE (...).

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