Fixing software bugs and adding new features are two of the major maintenance
tasks. Software bugs and features are reported as change requests. Developers
consult these requests and often choose a few keywords from them as an ad hoc
query. Then they execute the query with a search engine to find the exact
locations within software code that need to be changed. Unfortunately, even
experienced developers often fail to choose appropriate queries, which leads to
costly trials and errors during a code search. Over the years, many studies
attempt to reformulate the ad hoc queries from developers to support them. In
this systematic literature review, we carefully select 70 primary studies on
query reformulations from 2,970 candidate studies, perform an in-depth
qualitative analysis (e.g., Grounded Theory), and then answer seven research
questions with major findings. First, to date, eight major methodologies (e.g.,
term weighting, term co-occurrence analysis, thesaurus lookup) have been
adopted to reformulate queries. Second, the existing studies suffer from
several major limitations (e.g., lack of generalizability, vocabulary mismatch
problem, subjective bias) that might prevent their wide adoption. Finally, we
discuss the best practices and future opportunities to advance the state of
research in search query reformulations.Comment: 81 pages, accepted at TOSE