Semantic Search

This section lists and briefly describes all the components that are especially useful for semantic search.

ComponentAvailable ClassesDescription
RankerSentenceTransformersRankerOrders documents based on how relevant they are to the query.
Example usage:
In a query pipeline, after a keyword-based Retriever to rank the documents it returns.
ReaderFARMReader
TransformersReader
TableReader
RCIReader
Finds an answer by selecting a text span in documents.
Example usage:
In a query pipeline when you want to know the location of the answer.
RetrieverBM25Retriever

DensePassageRetriever

TableTextRetriever

EmbeddingRetriever

TfidfRetriever
Fetches relevant documents from the DocumentStore.
Example usage:
Coupling Retriever with a Reader in a query pipeline to speed up the search (the Reader only goes through the documents it gets from the Retriever).
QuestionGeneratorQuestionGeneratorWhen given a document, it generates questions this document can answer.
Example usage:
Auto-suggested questions in your search app.