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72 lines
2.6 KiB
Python
72 lines
2.6 KiB
Python
from __future__ import annotations
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import logging
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import sqlglot
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from sqlglot import exp
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logger = logging.getLogger(__name__)
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def extract_table_refs(sql: str, dialect: str = "postgres") -> list[tuple[str, ...]]:
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"""Return a deduped list of warehouse-table refs found in `sql` as
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tuples of normalized (lowercase, unquoted) name parts.
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Skips CTE self-references. Returns refs in the order they first appear
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so callers can present consistent error messages. Each tuple is the
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fully-qualified name as written in the SQL: `("staging", "shipments")`,
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`("analytics", "marts", "listings")`, or `("listings",)`.
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On parse failure returns []; coverage check is best-effort and must
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not break source writes when the SQL has unusual syntax.
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"""
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try:
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tree = sqlglot.parse_one(sql, dialect=dialect)
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except Exception as e:
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logger.debug("sql_table_extractor: parse failed (%s); skipping coverage", e)
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return []
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cte_names = {cte.alias_or_name.lower() for cte in tree.find_all(exp.CTE)}
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seen: set[tuple[str, ...]] = set()
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out: list[tuple[str, ...]] = []
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for t in tree.find_all(exp.Table):
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name = (t.name or "").lower()
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if not name or name in cte_names:
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continue
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parts: list[str] = []
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catalog = t.args.get("catalog")
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db = t.args.get("db")
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if catalog and getattr(catalog, "name", None):
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parts.append(catalog.name.lower())
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if db and getattr(db, "name", None):
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parts.append(db.name.lower())
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parts.append(name)
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ref = tuple(parts)
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if ref not in seen:
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seen.add(ref)
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out.append(ref)
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return out
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def normalize_table(value: str) -> tuple[str, ...]:
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"""Split a `table:` field value into normalized, lowercased parts."""
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return tuple(p.strip('"').strip("`").lower() for p in value.split(".") if p)
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def ref_matches_source_table(ref: tuple[str, ...], source_table: str) -> bool:
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"""True iff `ref` is a suffix of `source_table` (or vice versa for the
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1-part bare-name case).
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Examples:
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ref=(marts, listings) table=ANALYTICS.MARTS.LISTINGS → True
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ref=(analytics, marts, x) table=ANALYTICS.MARTS.X → True
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ref=(listings,) table=ANALYTICS.MARTS.LISTINGS → True (bare matches last)
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ref=(staging, shipments) table=ANALYTICS.MARTS.SHIPMENTS → False (db differs)
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"""
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src = normalize_table(source_table)
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if not src or not ref:
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return False
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if len(ref) > len(src):
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return False
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return src[-len(ref) :] == ref
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