On 29 January 2010 13:43, listread <listread@xxxxxxx> wrote: > Would this support the idea of putting a lock column in the table to be > locked? If an admin had cause to go into a table with a DB gui tool, at > least he would see the semaphore as a "warning". > > The same table would also simplify code and make the sb more portable. > > As for speed, you have to query that (those) records to be updated anyway at > some point - a special lock table would require another query and if it that > lock table was for ALL the other tables in the system, it would be getting > more hits than any one table. > > This has been very educational for me - thanks for the discussion. > You could easily extend this to be table locking. Assuming that the key is tableid/rowid, then you would need to include logic to handle tableid/null to indicate the whole table. Obviously, you can't put a table lock on if another user has a row or table lock. It does get a little more messy, but perfectly doable in a single SQL query. Where you put the lock is pretty much up to you, but the extra columns have no bearing on the table. They aren't data for that table. A semaphore table would be small. You can easily remove all the locks from all the tables/rows simply by truncating the semaphore table. The other way around all of this is to not do any locking at all. Simply log when a row is saved and when you go to save the row include ... where rows_last_edited_datetime = the_datetime_I_read_when_I_started_editing_the_row But I don't like that method. It is first saves wins, rather than locking. -- ----- Richard Quadling "Standing on the shoulders of some very clever giants!" EE : http://www.experts-exchange.com/M_248814.html EE4Free : http://www.experts-exchange.com/becomeAnExpert.jsp Zend Certified Engineer : http://zend.com/zce.php?c=ZEND002498&r=213474731 ZOPA : http://uk.zopa.com/member/RQuadling -- PHP Database Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
