On Mon, Aug 1, 2016 at 1:19 PM, Karan Sikka <karanssi...@gmail.com> wrote: > Following the patch to implement strpos with Boyer-Moore-Horspool, > it was proposed we bring BMH to LIKE as well. > > Original thread: > https://www.postgresql.org/message-id/flat/27645.1220635769%40sss.pgh.pa.us#27645.1220635...@sss.pgh.pa.us > > I'm a first time hacker and I found this task on the TODO list. It seemed > interesting and isolated enough. But after looking at the code in > like_match.c, it's clearly a non-trivial task. > > How desirable is this feature? To begin answering that question, > I did some initial benchmarking with an English text corpus to find how much > faster BMH (Boyer-Moore-Horspool) would be compared to LIKE, and the results > were as follows: BMH can be up to 20% faster than LIKE, but for short > substrings, it's roughly comparable or slower. > > Here are the results visualized: > > http://ctrl-c.club/~ksikka/pg/like-strpos-short-1469975400.png > http://ctrl-c.club/~ksikka/pg/like-strpos-long-1469975400.png
Based on these results, this looks to me like a pretty unexciting thing upon which to spend time. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
