The pg_trgm module provides GiST and GIN index operator classes that allow you to create an index over a text column for the purpose of very fast similarity searches. Returns the “ distance” between the arguments, that is one minus the strict_word_similarity() value. Returns the “ distance” between the arguments, that is one minus the word_similarity() value. Returns the “ distance” between the arguments, that is one minus the similarity() value. Returns true if its arguments have a similarity that is greater than the current similarity threshold set by pg_trgm.similarity_threshold. Thus, the strict_word_similarity function is useful for finding the similarity to whole words, while word_similarity is more suitable for finding the similarity for parts of words. # SELECT strict_word_similarity('word', 'two words'), similarity('word', 'words')

In the first string, the set of trigrams is. # SELECT word_similarity('word', 'two words') ( Deprecated instead use SET pg_trgm.similarity_threshold.) The threshold must be between 0 and 1 (default is 0.3). Sets the current similarity threshold that is used by the % operator. ( Deprecated instead use SHOW pg_trgm.similarity_threshold.) This sets the minimum similarity between two words for them to be considered similar enough to be misspellings of each other, for example. Returns the current similarity threshold used by the % operator. Since we don't have cross-word trigrams, this function actually returns greatest similarity between first string and any continuous extent of words of the second string. Same as word_similarity, but forces extent boundaries to match word boundaries. Strict_word_similarity ( text, text ) → real

Returns a number that indicates the greatest similarity between the set of trigrams in the first string and any continuous extent of an ordered set of trigrams in the second string. (In practice this is seldom useful except for debugging.) Returns an array of all the trigrams in the given string. The range of the result is zero (indicating that the two strings are completely dissimilar) to one (indicating that the two strings are identical).

Returns a number that indicates how similar the two arguments are.

String similarity