Skip to content

Router

RouterRetriever #

Bases: BaseRetriever

Router retriever.

Selects one (or multiple) out of several candidate retrievers to execute a query.

Parameters:

Name Type Description Default
selector BaseSelector

A selector that chooses one out of many options based on each candidate's metadata and query.

required
retriever_tools Sequence[RetrieverTool]

A sequence of candidate retrievers. They must be wrapped as tools to expose metadata to the selector.

required
Source code in llama-index-core/llama_index/core/retrievers/router_retriever.py
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
class RouterRetriever(BaseRetriever):
    """Router retriever.

    Selects one (or multiple) out of several candidate retrievers to execute a query.

    Args:
        selector (BaseSelector): A selector that chooses one out of many options based
            on each candidate's metadata and query.
        retriever_tools (Sequence[RetrieverTool]): A sequence of candidate
            retrievers. They must be wrapped as tools to expose metadata to
            the selector.

    """

    def __init__(
        self,
        selector: BaseSelector,
        retriever_tools: Sequence[RetrieverTool],
        llm: Optional[LLM] = None,
        objects: Optional[List[IndexNode]] = None,
        object_map: Optional[dict] = None,
        verbose: bool = False,
    ) -> None:
        self._llm = llm or Settings.llm
        self._selector = selector
        self._retrievers: List[BaseRetriever] = [x.retriever for x in retriever_tools]
        self._metadatas = [x.metadata for x in retriever_tools]

        super().__init__(
            callback_manager=Settings.callback_manager,
            object_map=object_map,
            objects=objects,
            verbose=verbose,
        )

    def _get_prompt_modules(self) -> PromptMixinType:
        """Get prompt sub-modules."""
        # NOTE: don't include tools for now
        return {"selector": self._selector}

    @classmethod
    def from_defaults(
        cls,
        retriever_tools: Sequence[RetrieverTool],
        llm: Optional[LLM] = None,
        selector: Optional[BaseSelector] = None,
        select_multi: bool = False,
    ) -> "RouterRetriever":
        llm = llm or Settings.llm
        selector = selector or get_selector_from_llm(llm, is_multi=select_multi)

        return cls(
            selector,
            retriever_tools,
            llm=llm,
        )

    def _retrieve(self, query_bundle: QueryBundle) -> List[NodeWithScore]:
        with self.callback_manager.event(
            CBEventType.RETRIEVE,
            payload={EventPayload.QUERY_STR: query_bundle.query_str},
        ) as query_event:
            result = self._selector.select(self._metadatas, query_bundle)

            if len(result.inds) > 1:
                retrieved_results = {}
                for i, engine_ind in enumerate(result.inds):
                    logger.info(
                        f"Selecting retriever {engine_ind}: " f"{result.reasons[i]}."
                    )
                    selected_retriever = self._retrievers[engine_ind]
                    cur_results = selected_retriever.retrieve(query_bundle)
                    retrieved_results.update({n.node.node_id: n for n in cur_results})
            else:
                try:
                    selected_retriever = self._retrievers[result.ind]
                    logger.info(f"Selecting retriever {result.ind}: {result.reason}.")
                except ValueError as e:
                    raise ValueError("Failed to select retriever") from e

                cur_results = selected_retriever.retrieve(query_bundle)
                retrieved_results = {n.node.node_id: n for n in cur_results}

            query_event.on_end(payload={EventPayload.NODES: retrieved_results.values()})

        return list(retrieved_results.values())

    async def _aretrieve(self, query_bundle: QueryBundle) -> List[NodeWithScore]:
        with self.callback_manager.event(
            CBEventType.RETRIEVE,
            payload={EventPayload.QUERY_STR: query_bundle.query_str},
        ) as query_event:
            result = await self._selector.aselect(self._metadatas, query_bundle)

            if len(result.inds) > 1:
                retrieved_results = {}
                tasks = []
                for i, engine_ind in enumerate(result.inds):
                    logger.info(
                        f"Selecting retriever {engine_ind}: " f"{result.reasons[i]}."
                    )
                    selected_retriever = self._retrievers[engine_ind]
                    tasks.append(selected_retriever.aretrieve(query_bundle))

                results_of_results = await asyncio.gather(*tasks)
                cur_results = [
                    item for sublist in results_of_results for item in sublist
                ]
                retrieved_results.update({n.node.node_id: n for n in cur_results})
            else:
                try:
                    selected_retriever = self._retrievers[result.ind]
                    logger.info(f"Selecting retriever {result.ind}: {result.reason}.")
                except ValueError as e:
                    raise ValueError("Failed to select retriever") from e

                cur_results = await selected_retriever.aretrieve(query_bundle)
                retrieved_results = {n.node.node_id: n for n in cur_results}

            query_event.on_end(payload={EventPayload.NODES: retrieved_results.values()})

        return list(retrieved_results.values())