shilpisingh-oracle/SQL-Optimization

1"""Utility helpers: safety checks, SQL normalization, result hashing."""2import re3import hashlib4import sqlparse5 6DANGEROUS_PATTERNS = [7    r"\bDROP\b",8    r"\bTRUNCATE\b",9    r"\bDELETE\b\s+FROM\b.*\bWHERE\b.*",  # allow DELETE with WHERE10    r"\bALTER\b.*DROP\b",11]12 13 14def is_sql_safe(sql: str) -> bool:15    """Return True if SQL appears safe to run (basic checks).16 17    Blocks DROP, TRUNCATE, ALTER ... DROP and DELETE without WHERE.18    This is a heuristic and not a guarantee.19    """20    up = sql.upper()21    # block plain DELETE without WHERE22    if re.search(r"\bDELETE\b\s+FROM\s+[\w\.]+\s*(;|$)", up):23        return False24    for pat in DANGEROUS_PATTERNS:25        if re.search(pat, up, flags=re.IGNORECASE):26            # allow DELETE with WHERE27            if re.search(r"\bDELETE\b.*\bWHERE\b", up, flags=re.IGNORECASE):28                continue29            return False30    return True31 32 33def normalize_sql(sql: str) -> str:34    """Normalize SQL for comparison/hashing (whitespace, casing, remove comments)."""35    # remove SQL comments36    parsed = sqlparse.format(sql, strip_comments=True)37    # remove extra whitespace and lowercase38    normalized = " ".join(parsed.split())39    return normalized.lower()40 41 42def hash_result(rows) -> str:43    """Create a stable hash for query result rows (list of tuples or pandas DataFrame)."""44    m = hashlib.sha256()45    if hasattr(rows, 'to_csv'):46        s = rows.to_csv(index=False)47        m.update(s.encode('utf-8'))48    else:49        # assume iterable of rows50        for r in rows:51            m.update(repr(r).encode('utf-8'))52    return m.hexdigest()53