94 lines
3.5 KiB
Python
94 lines
3.5 KiB
Python
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"""Reference LEXICAL baseline retrievers that mirror the production system.
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These exist so (a) the eval-set author can VERIFY a query's labels and check
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that paraphrase queries genuinely defeat lexical matching, and (b) later agents
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have an honest "current system" to beat.
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`SqliteFtsRetriever` builds an in-memory SQLite FTS5 index over the corpus and
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runs the SAME query shape the production local store uses:
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words -> '"w1" OR "w2" ...' MATCH, ORDER BY bm25(), importance as tiebreak.
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(README "SQLite: FTS5 with BM25".) This is the closest faithful, dependency-free
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baseline. The Postgres tsvector path is documented in the README; its ranking
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differs (weighted A/B/C/D + importance-first default) but for a quality ceiling
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comparison the FTS5/BM25 relevance ordering is the right lexical reference.
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"""
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from __future__ import annotations
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import re
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import sqlite3
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from collections.abc import Sequence
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from .types import Memory, MemoryId
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# FTS5 reserved-ish tokens; we quote every term anyway, but strip embedded quotes.
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_WORD_RE = re.compile(r"[A-Za-z0-9_]+")
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class SqliteFtsRetriever:
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"""Faithful FTS5/BM25 lexical baseline (mirrors local_store search)."""
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name = "sqlite_fts5_bm25"
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def __init__(self, sort_by: str = "relevance") -> None:
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# "relevance": ORDER BY bm25(), importance DESC (best for quality eval)
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# "importance": ORDER BY importance DESC, ... (production default)
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self.sort_by = sort_by
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self._con: sqlite3.Connection | None = None
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def build_index(self, corpus: Sequence[Memory]) -> None:
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con = sqlite3.connect(":memory:")
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con.execute(
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"""
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CREATE VIRTUAL TABLE memories_fts USING fts5(
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content, category, tags, expanded_keywords,
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memory_id UNINDEXED, importance UNINDEXED
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)
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"""
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)
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con.executemany(
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"INSERT INTO memories_fts(content, category, tags, expanded_keywords, memory_id, importance)"
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" VALUES (?,?,?,?,?,?)",
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[
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(m.content, m.category, m.tags, m.expanded_keywords, m.id, m.importance)
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for m in corpus
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],
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)
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con.commit()
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self._con = con
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def _fts_query(self, query: str) -> str:
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words = _WORD_RE.findall(query.lower())
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if not words:
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return ""
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return " OR ".join(f'"{w}"' for w in words)
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def retrieve(self, query: str, k: int) -> list[MemoryId]:
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assert self._con is not None, "call build_index first"
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match = self._fts_query(query)
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if not match:
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return []
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if self.sort_by == "importance":
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order = "importance DESC, bm25(memories_fts)"
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else:
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order = "bm25(memories_fts), importance DESC"
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try:
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rows = self._con.execute(
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f"SELECT memory_id FROM memories_fts WHERE memories_fts MATCH ? "
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f"ORDER BY {order} LIMIT ?",
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(match, k),
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).fetchall()
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except sqlite3.OperationalError:
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# mirror production LIKE fallback on FTS syntax errors
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like = f"%{query}%"
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rows = self._con.execute(
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"SELECT memory_id FROM memories_fts WHERE content LIKE ? OR tags LIKE ? "
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"ORDER BY importance DESC LIMIT ?",
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(like, like, k),
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).fetchall()
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return [r[0] for r in rows]
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def close(self) -> None:
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if self._con is not None:
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self._con.close()
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self._con = None
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