hum, maybe a 'global variable' + a 'counter' function could do the job? select add_and_return(@global_var,1) could return old global_var value +1, and set the global_var to +1
just a idea.. like GET_LOCK(str,timeout) do, but without timeout 2013/5/15 Gordan Bobic <[email protected]> > On 05/15/2013 09:06 PM, Michael Widenius wrote: > >> >> Hi! >> >> "Gordan" == Gordan Bobic <[email protected]> writes: >>>>>>> >>>>>> >> Gordan> How difficult would be be to implement working >> Gordan> auto-increment functionality on the BlackHole engine? >> >> Gordan> This would be really useful for what I'm trying to do at >> Gordan> the moment. Since it is not available and there are no >> Gordan> sequences in MariaDB and MySQL, I have to resort to a >> Gordan> hack such as a single-int-field table doing the >> Gordan> auto-increment, and an insert trigger on the blackhole >> Gordan> table to insert a null into the auto-increment >> Gordan> tracking table, get LAST_INSERT_ID() to set the >> Gordan> value in the auto-increment table, and then delete >> Gordan> the record. >> >> What problem is that you wanted to solve? >> Normally blackhole is used just for creating a slave of a slave that >> doesn't have to hold any data (only the logs). >> > > The problem is a huge volume logging application that needs to have > uniquely enumerated records for auditing purposes. > > > Gordan> Even with InnoDB log files and tablespace on tmpfs >> Gordan> this makes the performance nosedive by a factor of 4 >> Gordan> if the trigger doesn't bother cleaning up the >> Gordan> auto-increment table, and a factor of 13 if it >> Gordan> deletes the record immediately after inserting it. >> Gordan> The actual times I tested with 24 inserter threads >> Gordan> on a 24-thread server are 8m vs. 30m vs. 105m, i.e. >> Gordan> a massive drop. >> >> Why not use in memory tables for this? >> (ENGINE=MEMORY) >> > > My tests show that ENGINE=MEMORY has terrible concurrency. It behaves > essentially the same as MyISAM as far as write-concurrency is concerned. > Sure, it's faster than MyISAM in the single-thread case, but my testing has > shown that it doesn't scale past that single thread at all. Unfortunately, > the application in question has hundreds of concurrent writers. Performance > in my testing has been an order of magnitude worse with ENGINE=MEMORY than > with ENGINE=InnoDB with ibdata and ib_log files on tmpfs. > > Gordan > > > ______________________________**_________________ > Mailing list: > https://launchpad.net/~maria-**developers<https://launchpad.net/~maria-developers> > Post to : > maria-developers@lists.**launchpad.net<[email protected]> > Unsubscribe : > https://launchpad.net/~maria-**developers<https://launchpad.net/~maria-developers> > More help : > https://help.launchpad.net/**ListHelp<https://help.launchpad.net/ListHelp> > -- Roberto Spadim SPAEmpresarial
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