2009-08-12 Hide Zen home Pgsql GiST GIN SP-GiST Tsearch2 SAI RVO SAI CAS SOA Supernovae TODO HomePage Astronet Google Rambler Yandex Oddmuse E-R-E dict Index edit We introduce phrase operator ?[n], or phrase conjuction operator, which is similar logical conjuction operator ( AND, &), but preserve order of operands (non-commutative) and constraint distance between them (<=n) Logical conjuction operator (AND, &) is associative , commmutative , distributive , idempotent . In set theory intersection operator is an example of logical conjunction operator. The ? operator is non-commutative , so 'A ? B' ≠ 'B ? A' The ? operator is non-associative ( left-associative ) and evaluates from left to right. =# select '1 ? 2 ? 3'::tsquery = '(1 ? 2) ? 3'::tsquery; ?column? ---------- t but =# select '1 ? 2 ? 3'::tsquery = '1 ? (2 ? 3)'::tsquery; ?column? ---------- f Function *phraseto_...