A scoping review does not need to search as many databases as possible. In most cases, two to three well-chosen databases can provide appropriate coverage, while additional databases may simply create duplicate results, increase workload, and make your search strategy harder to justify.

What do databases actually do in a scoping review?

A database is a source of literature, and each database has its own strengths, subject coverage and indexing system. Using multiple databases is intended to capture the breadth of literature on your topic, reduce the risk of missing key studies, and balance subject-specific sources with broader databases.

However, different databases have a lot of overlap. Searching seven broad databases does not necessarily give you seven times the coverage. It can simply return many of the same papers.

The goal is therefore not to search everywhere. Your goal is to search the right places for your topic. Database selection should reflect the literature you need to find and the disciplinary landscape of your research area.

Why don’t you need lots of databases?

Searching too many databases does not automatically make a scoping review more rigorous. It can make the process more repetitive because databases in education, social sciences and health may index many of the same journals.

There is also a practical cost. Each database has its own search operators, filters and export settings, creating additional work. For many students, the marginal benefit of adding a fifth or sixth database may be very small compared with the time required.

Database selection can also affect how clearly you justify your methods. Including databases that do not align with your topic can raise questions about whether you understand the disciplinary landscape. Adding engineering or economic databases simply because you feel you need “more” databases does not necessarily strengthen the review.

A clean, justified search strategy is more useful than an inflated list of sources.

So how many databases do you actually need?

For most scoping reviews, two to three well-chosen databases is more than enough.

A simple framework is:

1. One subject-specific database

   Choose the database most closely aligned with your field. For example:

   • Education → ERIC

   • Health → CINAHL, Medline

   • Psychology → PsycINFO

   • Business → Business Source Complete

2. One broad database

   Use a broader database to help capture interdisciplinary material:

   • Scopus

   • Web of Science

3. One optional specialist or supplementary database

   Add this only if it genuinely relates to your area:

   • Qualitative work → SocINDEX

   • Technology → IEEE Xplore

   • Global health → Global Health

   • Policy papers → ProQuest

Anything beyond this may add little value unless you are conducting a highly technical review or working on a doctoral-level systematic review.

Why is your justification more important than the number of databases?

The number of databases you use is not, by itself, what makes your search strategy strong. What matters is whether your choices make sense for your topic and whether you can clearly justify them.

A long list of databases can give the impression of a comprehensive search, but redundant or irrelevant databases may simply create more results and more work without meaningfully improving coverage.

When setting up your scoping review, focus on selecting databases that correspond to your subject area and the literature you need to identify. Your methods section should make that logic clear.

If you're applying this to your own work and want a second pair of eyes: research support