Multi-Hop Table Retrieval for Open-Domain Text-to-SQL
Xuanliang Zhang Dingzirui Wang Longxu Dou Qingfu Zhu Wanxiang Che
Open-domain text-to-SQL is an important task that retrieves question-relevant
tables from massive databases and then generates SQL. However, existing
retrieval methods that retrieve in a single hop do not pay attention to the
text-to-SQL challenge of schema linking, which is aligning the entities in the
question with table entities, reflected in two aspects: similar irrelevant
entity and domain mismatch entity. Therefore, we propose our method, the
multi-hop table retrieval with rewrite and beam search (Murre). To reduce the
effect of the similar irrelevant entity, our method focuses on unretrieved
entities at each hop and considers the low-ranked tables by beam search. To
alleviate the limitation of domain mismatch entity, Murre rewrites the question
based on retrieved tables in multiple hops, decreasing the domain gap with
relevant tables. We conduct experiments on SpiderUnion and BirdUnion+, reaching
new state-of-the-art results with an average improvement of 6.38%.