class DuckDBRetriever(BaseRetriever):
def __init__(
self,
database_name: Optional[str] = ":memory:",
table_name: Optional[str] = "documents",
text_search_config: Optional[dict] = {
"stemmer": "english",
"stopwords": "english",
"ignore": r"(\\.|[^a-z])+",
"strip_accents": True,
"lower": True,
"overwrite": True,
},
persist_dir: Optional[str] = "./storage",
node_id_column: Optional[str] = "node_id",
text_column: Optional[str] = "text",
# TODO: Add more options for FTS index creation
similarity_top_k: int = DEFAULT_SIMILARITY_TOP_K,
callback_manager: Optional[CallbackManager] = None,
verbose: bool = False,
) -> None:
self._similarity_top_k = similarity_top_k
self._callback_manager = callback_manager
self._verbose = verbose
self._table_name = table_name
self._node_id_column = node_id_column
self._text_column = text_column
# TODO: Check if the vector store already has data
# Create an FTS index on the 'text' column if it doesn't already exist
if database_name == ":memory:":
self._database_path = ":memory:"
else:
self._database_path = os.path.join(persist_dir, database_name)
strip_accents = 1 if text_search_config["strip_accents"] else 0
lower = 1 if text_search_config["lower"] else 0
overwrite = 1 if text_search_config["overwrite"] else 0
ignore = text_search_config["ignore"]
sql = f"""
PRAGMA create_fts_index({self._table_name}, {self._node_id_column}, {self._text_column},
stemmer = '{text_search_config["stemmer"]}',
stopwords = '{text_search_config["stopwords"]}', ignore = '{ignore}',
strip_accents = {strip_accents}, lower = {lower}, overwrite = {overwrite})
"""
with DuckDBLocalContext(self._database_path) as conn:
conn.execute(sql)
def _retrieve(self, query_bundle: QueryBundle) -> List[NodeWithScore]:
if self._verbose:
logger.info(f"Searching for: {query_bundle.query_str}")
query = query_bundle.query_str
sql = f"""
SELECT
fts_main_{self._table_name}.match_bm25({self._node_id_column}, '{query}') AS score,
{self._node_id_column}, {self._text_column}
FROM {self._table_name}
WHERE score IS NOT NULL
ORDER BY score DESC
LIMIT {self._similarity_top_k};
"""
with DuckDBLocalContext(self._database_path) as conn:
query_result = conn.execute(sql).fetchall()
# Convert query result to NodeWithScore objects
retrieve_nodes = []
for row in query_result:
score, node_id, text = row
node = TextNode(id=node_id, text=text)
retrieve_nodes.append(NodeWithScore(node=node, score=float(score)))
return retrieve_nodes
