KDB Basic Search Query Syntax

Here are some query examples demonstrating the query syntax.

Exact word or phrase matching

In order to search for exact word or phrase (group of words) surround the word or phrase in double quotes.

Example :- "spectrum", "spread spectrum"

Wildcard Searches

System 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

System 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 "spectrum" use the fuzzy search:

spectrum~

This search will find terms like spectrum and spectral.

Proximity Searches

Lucene supports finding words are a within a specific distance away. To do a proximity search use the tilde, "~", symbol at the end of a Phrase. For example to search for a "Spread" and "spectrum" within 10 words of each other in a document use the search:

"Spread spectrum"~10

Boolean Operators

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

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 "spread spectrum" or just "spread" use the query:

"spread spectrum" spread

or

" spread spectrum " OR spread

AND

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 "spread spectrum" and "Rule part 15" use the query:

" spread spectrum " AND " Rule part 15"

+

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 "spectrum" and may contain "equipment" use the query:

+spectrum equipment

NOT

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 "spread spectrum" but not "rule part 15" use the query:

"spread spectrum" NOT "rule part 15"

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

NOT "spread spectrum"

-

The "-" or prohibit operator excludes documents that contain the term after the "-" symbol.

To search for documents that contain "spread spectrum" but not "rule part 15" use the query:

"spread spectrum" -"rule part 15"

Escaping Special Characters

System supports escaping special characters that are part of the query syntax. The current list special characters are

+ - && ()|| ! " ~ * ?

To escape these character use the \ before the character. For example to search for 15.231(e) use the query:

15.231\(e\)