On 14.11.2007 12:50 CE(S)T, Martijn Tonies wrote: > Yves, > > Did you read this reply I send earlier? I think it does what you > want without needing to "lock" anything, thus making it portable.
>> I would suggest the following -- >> >> create a table called "SEQUENCES": Yes, I've read it and actually put a flag on that message, but then I decided to go for the other flagged message that explained SELECT ... FOR UPDATE. I did some tests with multiple client windows and found that the locking is good enough. I use it for finding new ID values and for telling whether a new value is unique where UNIQUE constraints won't help me (because I want the values to be caseless unique e.g.). SELECT ... FOR UPDATE works fine when I always use the same function to access that table. It is supported by MySQL, PostgreSQL and Oracle. I only need a small workaround for SQLite (which gets the "FOR UPDATE" stripped off and instead requires the programmer to have started an EXCLUSIVE transaction before; else -> Exception). Sequences, if I got that right, need the new value to be stored immediately, i.e. outside of an active transaction. This requires a second connection to the database which probably causes more implementation work for my web application. I don't need LOCK TABLES anymore now. And at last, I can say that this is indeed not a simple topic as I've thought and maybe I've read most of the related documentation now anyway... -- Yves Goergen "LonelyPixel" <[EMAIL PROTECTED]> Visit my web laboratory at http://beta.unclassified.de -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
