Re: Change of Logging Status: Implications?

Will Hartung - Master Rallyeist (villy@collinscomp.com) wrote: : Human beings are horribly unreliable in computer terms. It gets even : worse with Online 5.X because of its index locking scheme. If you have : a document table that has something like an incrementing document : number as its primary key, when someone inserts a row into that table, : NO ONE ELSE will be able to insert a row, until the transaction is : committed. This is because a lock is placed not only on the new row, : but on the next INDEX entry, preventing someone from inserting a higher : valued entry. What you're referring to is Adjacent Key Locking, and it used to work exactly the other way around. When you insert a row, it TEST-locks the next higher key value, but only holds a lock on the current key value. Prior to 4.11 and 5.01, this meant that when someone inserted a row, no one else could insert the next LOWEST index entry -- there was never a problem with inserting a higher entry. As of 4.11 and 5.01, AKL was changed to use intent-exclusive locks on inserts, thus eliminating any problem with adjacent inserts (however, other AKL side-effects remained). AKL has been replaced by Key-Value Locking in DSA. June ---- June Tong Informix Software ---- ---- Senior Consultant (415) 926-6140 ---- ---- International Support junet@informix.com ---- ---- Location-du-jour: Beijing ---- * * Standard disclaimers apply * - Please do not send me requests/questions by mail. When I have the knowledge - and time permits, I try to answer questions on comp.databases.informix, but - travel schedule, time, and volume make responding to personal requests - difficult and often slow. Please call your local Informix Technical Support - organization for assistance with technical issues.