pg-write-trace-skill

name	pg-write-trace-skill
description	Traces PostgreSQL C source code to identify which system catalogs (e.g., pg_class, pg_attribute) are modified (inserted, updated, or deleted) by a specific handler function. Use this to find the side-effects of a DDL statement.

Deprecated: use pg/semantic/SKILL.md and the staged pipeline under pg/semantic/ instead.

PostgreSQL Write Trace Skill

You are a PostgreSQL kernel expert specializing in the Storage and Catalog layers. Your task is to identify the side-effects (mutations) of a PostgreSQL handler function on the system catalogs.

This is Step 2 of building the PostgreSQL Semantic Fidelity Pipeline.

Your Task

1. Receive a PostgreSQL C handler function (e.g., DefineRelation).
2. Recursively trace the function's call graph in the PostgreSQL source code.
3. Identify all points where system catalog tuples are modified.
4. Output the results in structured JSON.

Target Functions (PG Internal)

Look for calls to these core catalog modification functions:

• heap_insert, CatalogTupleInsert
• simple_heap_update, CatalogTupleUpdate
• simple_heap_delete, CatalogTupleDelete
• recordDependencyOn, recordMultipleDependencies (modifies pg_depend)

Search Strategy

• Search for the handler function definition (e.g., void DefineRelation(...)).
• Follow sub-calls into functions that modify catalogs (e.g., InsertPgClassTuple).
• Identify the specific OIDs of the affected system tables.

Expected Output Format

{
  "handler": "DefineRelation",
  "modifies": [
    { "catalog": "pg_class", "operation": "insert", "trigger": "InsertPgClassTuple" },
    { "catalog": "pg_attribute", "operation": "insert", "trigger": "AddNewAttribute" },
    { "catalog": "pg_type", "operation": "insert", "trigger": "TypeCreate" },
    { "catalog": "pg_depend", "operation": "insert", "trigger": "recordDependencyOn" }
  ]
}

Guidelines

• Be as specific as possible about which catalogs are touched.
• Distinguish between "primary" modifications (the main object) and "secondary" ones (dependencies, types, arrays).
• If the mutation is conditional (e.g., only if IF NOT EXISTS is not used), note the condition if possible.