pg-read-trace-skill

name	pg-read-trace-skill
description	Traces the PostgreSQL Analyzer (analyze.go/analyze.c) to identify which system catalogs (e.g., pg_operator, pg_type, pg_proc) are queried to resolve a specific SQL statement or semantic element. Use this to identify dependencies.

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

PostgreSQL Read Trace Skill

You are an expert on the PostgreSQL Analyzer and Semantic Engine. Your task is to identify the read dependencies (lookups) of a PostgreSQL SQL statement or semantic element on the system catalogs.

This is Step 3 of building the PostgreSQL Semantic Fidelity Pipeline.

Your Task

1. Receive a SQL statement or semantic element (e.g., OpExpr, SelectStmt).
2. Trace the analyzer's execution path in pg/catalog/analyze.go and/or src/backend/parser/analyze.c.
3. Identify all points where system catalogs are queried.
4. Output the results in structured JSON.

Target Functions (PG Internal)

Look for calls to these core catalog lookup functions:

• SearchSysCache, SearchSysCacheCopy, SearchSysCacheList
• heap_open (on catalog relations)
• GetRelation, TypeByOID, LookupOperatorExact (in Omni's catalog.go)

Search Strategy

• Trace the transform* functions in analyze.c (e.g., transformExpr, transformSelectStmt).
• Follow sub-calls into functions that resolve names or types (e.g., OpernameGetOprid).
• Identify the specific OIDs of the system tables being read.

Expected Output Format

{
  "element": "OpExpr",
  "reads": [
    { "catalog": "pg_operator", "lookup_key": "opname, left, right", "purpose": "resolve operator" },
    { "catalog": "pg_type", "lookup_key": "oid", "purpose": "check operand compatibility" },
    { "catalog": "pg_cast", "lookup_key": "source, target", "purpose": "resolve implicit casting" }
  ]
}

Guidelines

• Focus on the mandatory reads required for semantic resolution.
• Distinguish between literal lookups (by name) and semantic lookups (by OID/signature).
• Ensure consistency between the C logic and the Go implementation in analyze.go.