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Keyword Searches

Keyword searches are parsed into a series of terms and operators.

Terms can be a single word — plankton or carbon — or a phrase surrounded by double quotes — "ocean acidification"

Operators allow you to customize the text search in the following ways:  

Wildcards

Wildcard searches can be run on individual terms, using:

? to replace a single character:

carbon?te

* to replace zero or more characters:,

ocean acid*

Boolean Operators

The preferred operators are:

+ (this term must be present)

- (this term must not be present)

"coral calcification" +biota -pacific

- biota must be present

- pacific must not be present

- "coral calcification" is optional - its presense increases the relevance

Fuzzy Matching

We can search for terms that are similar to, but not exactly like our search terms, using the "fuzzy" operator: ~. This uses the Damerau-Levenshtein distance to find all terms with a maximum of two changes, where a change is the insertion, deletion or substitution of a single character, or transposition of two adjacent characters. The default edit distance is 2, but you can specify the distance:

"carbon"~3

Proximity Searches

While a phrase query (eg "john smith") expects all of the terms in exactly the same order, a proximity query allows the specified words to be further apart or in a different order. In the same way that fuzzy queries can specify a maximum edit distance for characters in a word, a proximity search allows us to specify a maximum edit distance of words in a phrase:

"primary production"~3