On Fri, May 31, 2013 at 4:25 AM, Alexander Korotkov <aekorot...@gmail.com> wrote: > On Thu, May 30, 2013 at 12:49 PM, Sawada Masahiko <sawada.m...@gmail.com> > wrote: >> >> following emails are discussed about partial match of pg_trgm. I hope >> will this help. >> >> <http://www.postgresql.org/message-id/cahgqgwfjshvv2ngme19wdtw9tefw_w7h2ns4e+yysjkb9wd...@mail.gmail.com> >> as you may know, if search string contains multibyte characters >> trigram key is converted to CRC of 4 byte and it is used as key. >> (but only use upper 3 byte from CRC) >> so we can do partial matching if KEEPONLYALNUM is enabled. > > > Please, read the further discussion on that thread. We can't do partial > matching because of CRC independently of KEEPONLYALNUM. >
Also, a few more questions: 1) When building a trgm index, are there any differences for multi-byte character strings. For example, would a 2 character Japanese string (multi-byte offcourse) produce exactly 3 trigrams to be stored in the index which would later be used while look-up? 2) And if that is so, is there problem in gin_extract_query_trgm(), that is while generating trigrams from a query search term that causes trigrams (stored in the index if answer to (1) is yes) NOT to be used in such a partial matching case? -- Amit Langote -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
