feat: support SET search_path for functions

[tianzhou]

Part of #227 - 4. Function Metadata

Add support for the SET search_path clause in function definitions, commonly used with SECURITY DEFINER for security hardening.

• Add SearchPath field to Function IR struct
• Extract search_path from pg_proc.proconfig in inspector query
• Generate SET search_path = 'value' clause in DDL output
• Include SearchPath in function equality comparisons

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR adds support for the SET search_path clause in PostgreSQL function definitions, which is commonly used with SECURITY DEFINER functions for security hardening. The implementation extracts the search_path configuration from the database's pg_proc.proconfig and includes it in the generated DDL.

Key changes:

• Added SearchPath field to the Function IR struct for storing the search_path value
• Modified database queries to extract search_path from pg_proc.proconfig using regex
• Updated DDL generation to output the SET search_path clause in function definitions

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
ir/ir.go	Added SearchPath field to Function struct
ir/queries/queries.sql	Added SQL query to extract search_path from pg_proc.proconfig
ir/queries/queries.sql.go	Generated code from updated queries.sql
ir/inspector.go	Added logic to populate SearchPath field when building functions
internal/diff/function.go	Added SET search_path clause generation and equality comparison
testdata/diff/create_function/add_function/.	Test data showing SET search_path clause in function output

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[Copilot]

The regex pattern substring(cfg FROM 'search_path=(.*)') will greedily match everything after the equals sign, including trailing whitespace or other content if the proconfig array contains multiple settings. While this may work for single settings, it could capture unintended characters.

Consider using a more precise pattern that accounts for PostgreSQL's actual storage format, or trimming the result to handle edge cases more robustly.

Suggested change

	(SELECT substring(cfg FROM 'search_path=(.*)') FROM unnest(p.proconfig) AS cfg WHERE cfg LIKE 'search_path=%') AS search_path
	(SELECT btrim(split_part(cfg, '=', 2)) FROM unnest(p.proconfig) AS cfg WHERE cfg LIKE 'search_path=%') AS search_path

[Copilot]

The regex pattern substring(cfg FROM 'search_path=(.*)') will greedily match everything after the equals sign, including trailing whitespace or other content if the proconfig array contains multiple settings. While this may work for single settings, it could capture unintended characters.

Consider using a more precise pattern that accounts for PostgreSQL's actual storage format, or trimming the result to handle edge cases more robustly.

Suggested change

	(SELECT substring(cfg FROM 'search_path=(.*)') FROM unnest(p.proconfig) AS cfg WHERE cfg LIKE 'search_path=%') AS search_path
	(SELECT btrim(split_part(cfg, '=', 2)) FROM unnest(p.proconfig) AS cfg WHERE cfg LIKE 'search_path=%') AS search_path