postgres

Commit Graph

Author	SHA1	Message	Date
Tom Lane	80a5cf643a	Improve contrib/pg_trgm's heuristics for regexp index searches. When extracting trigrams from a regular expression for search of a GIN or GIST trigram index, it's useful to penalize (preferentially discard) trigrams that contain whitespace, since those are typically far more common in the index than trigrams not containing whitespace. Of course, this should only be a preference not a hard rule, since we might otherwise end up with no trigrams to search for. The previous coding tended to produce fairly inefficient trigram search sets for anchored regexp patterns, as reported by Erik Rijkers. This patch penalizes whitespace-containing trigrams, and also reduces the target number of extracted trigrams, since experience suggests that the original coding tended to select too many trigrams to search for. Alexander Korotkov, reviewed by Tom Lane	11 years ago
Bruce Momjian	7e04792a1c	Update copyright for 2014 Update all files in head, and files COPYRIGHT and legal.sgml in all back branches.	12 years ago
Robert Haas	cacbdd7810	Use appendStringInfoString instead of appendStringInfo where possible. This shaves a few cycles, and generally seems like good programming practice. David Rowley	12 years ago
Tom Lane	6f5b8beb64	Make contrib/pg_trgm also support regex searches with GiST indexes. This wasn't addressed in the original patch, but it doesn't take very much additional code to cover the case, so let's get it done. Since pg_trgm 1.1 hasn't been released yet, I just changed the definition of what's in it, rather than inventing a 1.2.	12 years ago
Tom Lane	3ccae48f44	Support indexing of regular-expression searches in contrib/pg_trgm. This works by extracting trigrams from the given regular expression, in generally the same spirit as the previously-existing support for LIKE searches, though of course the details are far more complicated. Currently, only GIN indexes are supported. We might be able to make it work with GiST indexes later. The implementation includes adding API functions to backend/regex/ to provide a view of the search NFA created from a regular expression. These functions are meant to be generic enough to be supportable in a standalone version of the regex library, should that ever happen. Alexander Korotkov, reviewed by Heikki Linnakangas and Tom Lane	12 years ago

5 Commits (5f508b6dea19b66961c645bf5e5c427ac3af8359)