Hey, The thing with Oracle is that once a row is assigned a ROWID, it never changes. It doesn't matter if the row grows and has to move within the block (or if it has to move to another block, for that matter). That's why ROWIDs work in Oracle.
But apparently, that's not the case with MySQL (personally, I see that as a design flaw, but that's just my opinion :) so a ROWID in MySQL is really just a synonym for the primary key, and is probably only useful to people who are porting from Oracle (or some other database which has ROWIDs). Dean. -----Original Message----- From: [EMAIL PROTECTED] [mailto:horizonx@;noos.fr] Sent: Thursday, 14 November 2002 9:52 pm To: [EMAIL PROTECTED] Subject: Re: _rowid Hi Benjamin, > > Isn't _rowid some type of internal variable? What is its exact > purpose and > > significance? Thanks for nailing the matter down. > http://lists.mysql.com/cgi-ez/ezmlm-cgi?1:msn:39492:cnfpdcnkgalicmjgekef "My main concern is that if we would make ROWID's available for the end user, some may use this instead of auto_increment columns and cause a lot of problems. Internally it shouldn't be that hard to allow one to allow one to use a pseudo ROWID column to access a row but this would only be really usable for some very special applications. In most cases the current keys are just fast enough. Regards, Monty" Somehow Oracle does not share this view and makes true rowid available. Would some type of rowid feature lock help in making sure the user has read the relevant manual section and understands the caveats associated with rowid? > > > Do you have an example where _rowid would be more useful than > > > simply having an AUTO_INCREMENT column? A software developer could use Mysql to manage a very large memory space that needs indexing for certain variables (rows). Since that space is managed in the same way he RAM would be, stale data is simply marked and made available for reuse. The speed benefits make it worth loosing the ability to delete rows, use ALTER or OPTIMIZE, although I can't do without REPAIR ... As outlined in the link you found, true rowid takes no space whatsoever, no row, no key. Also what happens to an AUTO_INCREMENT column when there are over 4 billions plus rows? Regards, Terry --------------------------------------------------------------------- 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
