Search engine manual

» Terms and operators

Search engine provides the ability to create your own queries.

A query is broken up into terms and operators.
There are two types of terms: Single Terms and Phrases.

A Single Term is a single word such as "test" or "hello".
A Phrase is a group of words surrounded by double quotes such as "hello dolly".
Multiple terms can be combined together with Boolean operators to form a more complex query.

Boolean operators allow terms to be combined through logic operators. Search engine supports AND, "+", OR, NOT and "-" as Boolean operators (Note: Boolean operators must be ALL CAPS).

» Operators OR, AND, NOT

The OR operator is the default conjunction operator. This means that if there is no Boolean operator between two terms, the OR operator is used. The OR operator links two terms and finds a matching document if either of the terms exist in a document. This is equivalent to a union using sets. The symbol || can be used in place of the word OR.

To search for documents that contain either "polish jews" or just "polish" use the query:

"Polish Jews" Polish

or

"Polish Jews" OR polish

The AND operator matches documents where both terms exist anywhere in the text of a single document. This is equivalent to an intersection using sets. The symbol && can be used in place of the word AND.
To search for documents that contain "Polish Jews" and "American Jews" use the query:

"Polish Jews" AND "American Jews"


The "+" or required operator requires that the term after the "+" symbol exist somewhere in a the field of a single document.

To search for documents that must contain "polish" and may contain "american" use the query:

+polish american

The NOT operator excludes documents that contain the term after NOT. This is equivalent to a difference using sets. The symbol ! can be used in place of the word NOT.

To search for documents that contain "Polish Jews" but not " American Jews " use the uery:

"Polish Jews" NOT "American Jews"

Note: The NOT operator cannot be used with just one term. For example, the following search will return no results:

NOT "Polish Jews"

» Character wildcard

Search engine supports single and multiple character wildcard searches within single terms (not within phrase queries).

To perform a single character wildcard search use the "?" symbol.

To perform a multiple character wildcard search use the "*" symbol.

The single character wildcard search looks for terms that match that with the single character replaced. For example, to search for "text" or "test" you can use the search:

te?t

Multiple character wildcard searches looks for 0 or more characters. For example, to search for test, tests or tester, you can use the search:

test*

You can also use the wildcard searches in the middle of a term.

te*t

Note: You cannot use a * or ? symbol as the first character of a search.

» Fuzzy searches

Search engine supports fuzzy searches based on the Levenshtein Distance, or Edit Distance algorithm. To do a fuzzy search use the tilde, "~", symbol at the end of a Single word Term. For example to search for a term similar in spelling to "roam" use the fuzzy search:

roam~

This search will find terms like foam and roams.

Starting with search engine an additional (optional) parameter can specify the required similarity. The value is between 0 and 1, with a value closer to 1 only terms with a higher similarity will be matched. For example:

roam~0.8

The default that is used if the parameter is not given is 0.5.