| Welcome to WebmasterWorld Guest from 126.96.36.199 |
register, free tools, login, search, pro membership, help, library, announcements, recent posts, open posts,
|Pubcon Platinum Sponsor 2014|
|[mysql] how do u optimize Select Newest N result from BIG range|
TABLE thread (
ctime INT, (creation time)
PRIMARY KEY threadid, auto_increment
select .. from thread where forumid=1 and ctime>$one_month_ago order by ctime DESC
EXPLAIN gives "use index" and NO filesort, thus mysql will find by index as stop as soon as LIMIT exceed
but i now modify "forumid=1" to "forumid IN($idlist)", and EXPLAN gives "use index, filesort", which will get ALL match result from table into tmpfile, and sort as soon as LIMIT of rows is found.
btw: $idlist is not too much, but "thread"s in it is too many rows
All trademarks and copyrights held by respective owners. Member comments are owned by the poster.
WebmasterWorld is a Developer Shed Community owned by Jim Boykin.
© Webmaster World 1996-2014 all rights reserved