Minimum Should Match

Minimum Should Match is another search technique that allows you to conduct a more controlled search on related or co-occurring topics by specifying the number of search terms or phrases in the query that should occur within the records returned. The boolean operator OR returns results where at least one of the search terms or phrases appears within the records returned. Minimum should match allows you to specify the number of matched terms or phrases required to occur in a document in order to be returned in the results.

To execute a minimum should match query use the following syntax in the example below:

    {mm=2} “lung cancer” COPD lymphoma

The query must begin with {mm= } where the number of terms that have to be matched in the records returned follows the equal sign ( = ), without a space between the equal sign (=) and the number of terms to match. Next, enter a series of search terms and phrases. If there are certain terms or phrases that are required to appear in the records returned include a plus sign ( + ) directly in front of the search term or phrase. For example:

    {mm=2} “lung cancer” +COPD lymphoma “lung disease”

In the above example, COPD will appear in all records returned and at least 2 of the remaining search terms and phrases will appear in the records returned.

It should be noted that minimum should match overrides the selected search operator selected to the right of the search bar. Minimum should match only works with OR boolean queries. When a plus sign (+), which means required, is placed in front of a search term or phrase it is not included in the execution of the minimum should match query because minimum should match is only executed on optional terms and phrases.

Alternatively, to exclude a search term or phrase from appearing in the documents returned, include a minus sign ( - ) directly in front of the search term or phrase. For example:

{mm=2} "lung cancer" -COPD lymphoma "lung disease"

In the example above, COPD will be excluded for the records returned and at least 2 of the remaining search terms or phrases will appear in the records returned.

Minimum should match is most useful when querying a large number of search terms or phrases where only some of the terms are necessary to be considered relevant to the search but OR is too lenient. The results are sorted by relevance where records containing the most number of matched search terms or phrases appear at the top of the results table and as fewer terms or phrases are matched in the records returned the lower down the table the records appear.