Hi Again Sasha, You will find that explain is not always accurate. It makes guesses about the date based on statistics stored with the table files. It does not actually run the query, however if you dumped the table and reimported the table table on Linux you would probably get the same result.
Ken ----- Original Message ----- From: "sascha mantscheff" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Wednesday, March 20, 2002 6:40 AM Subject: different row count in explain select on different systems > I run mysql on a SuSe 7.3 and a FreeBSD 4.5 server. > The FreeBSD mysql version is 3.23.49. > The linux mysql version is 3.23.33. > > I just copied a large table using mysqldump | mysql from the linux server to > the FreeBSD server. > > An explain statement on a select on this table shows different row counts on > both systems: > > #SUSE: mysql> explain select id from boardmessages where board=4301 and > parent=0 order by id desc limit 0,20; > +---------------+------+---------------+-------+---------+-------+---- ---+----------------------------+ > | table | type | possible_keys | key | key_len | ref | rows | > Extra | > +---------------+------+---------------+-------+---------+-------+---- ---+----------------------------+ > | boardmessages | ref | board,parent | board | 4 | const | 16671 | > where used; Using filesort | > +---------------+------+---------------+-------+---------+-------+---- ---+----------------------------+ > > > #FREEBSD: mysql> explain select id from boardmessages where board=4301 and > parent=0 order by id desc limit 0,20; > +---------------+------+---------------+-------+---------+-------+---- ---+----------------------------+ > | table | type | possible_keys | key | key_len | ref | rows | > Extra | > +---------------+------+---------------+-------+---------+-------+---- ---+----------------------------+ > | boardmessages | ref | board,parent | board | 4 | const | 13629 | > where used; Using filesort | > +---------------+------+---------------+-------+---------+-------+---- ---+----------------------------+ > > Can anyone explain this strange deviation? > > s.m. > > -------------------------------------------------------------------- - > Before posting, please check: > http://www.mysql.com/manual.php (the manual) > http://lists.mysql.com/ (the list archive) > > To request this thread, e-mail <[EMAIL PROTECTED]> > To unsubscribe, e-mail <[EMAIL PROTECTED]> > Trouble unsubscribing? Try: http://lists.mysql.com/php/unsubscribe.php > > --------------------------------------------------------------------- Before posting, please check: http://www.mysql.com/manual.php (the manual) http://lists.mysql.com/ (the list archive) To request this thread, e-mail <[EMAIL PROTECTED]> To unsubscribe, e-mail <[EMAIL PROTECTED]> Trouble unsubscribing? Try: http://lists.mysql.com/php/unsubscribe.php
