24.02.2017 2:41, Leyne, Sean wrote: > >>> These connections perform only a few heavy weight SQL statements >> (taking max 3-4 of real execution time). >> > Most of the time is spent in the Firebird engine waiting for the next >> fetch, >> due to network latencies. >> >> In the engine ? > > Yes, the engine would be **waiting** for the next fetch request from the > client.
Engine never waits for the client ! This is against client-server architecture. >> Probably you want to say in the application\client ? Also it is >> very interesting how do you evaluate that numbers. > > Consider: > - Timeout set to 10 minutes > - a SELECT, which when tested using local IBExpert, that takes 1 minutes to > execute and return a result set of 10,000 rows > - the real client application which takes 0.2 seconds per row to perform some > required operation. > > Based on your logic, the SELECT would be killed after 10 minutes, with only > 3,000 rows having been processed by the client application. > > Following my logic, any time waiting for a "fetch" would not count, and thus > all 10,000 rows would be processed -- > but the transaction/connection would be 'active' for 33 minutes. Following *logic* developer should set timeout based on application processing time or (much better) fetch whole resultset, *commit* ASAP, and then process data. You describe very bad application (sorry) which holds open transaction 33 times longer than necessary. >> The main question is - do you need such benefit at all, and, if so, how >> much >> efforts you are willing to spend on it ? > > Yes, 'cus for me the true cost of a statement is not elapsed time but > "working time". > > Sitting waiting doesn't cost anything. Wrong. It costs memory and creates long runnig transactions at least. >> If you insist on changes in implementation, please, specify exactly what >> you >> need and where it is implemented in a such way. > > Add logic to stop and start the timer in locations where the server is waiting > for client requests/"fetch" operations. No, sorry, without me. This is against my feeling of common sence and against all my experience. I could agree to completely exclude fetches from timeout scope, i.e. stop timer right after execute()\open(), but i'm not sure it is correct way. > Where else is it implemented? > > I really don't know anywhere, however: Because it is not exists. > 1- I don't know of any other engines which allow for results to be fetched in > "pages". > It is the fact that the results can be fetch in "pages" with Firebird that, > IMO, raises > the need for the additional level of 'accounting'. I see no relation of batch fetches (if you speak about it) with all said above. > 2- my review of the MS SQL and Oracle documentation, all I found was about > how the client > could be configured to stop execution, not to have the server stop an > operation itself. MSSQL implements timeouts at client side: https://blogs.msdn.microsoft.com/khen1234/2005/10/20/theres-no-such-thing-as-a-query-timeout/ https://msdn.microsoft.com/en-us/library/system.data.sqlclient.sqlcommand.commandtimeout(v=vs.110).aspx I already described this approach and show why server side timeouts was choosen instead. Server-side statement timeouts implemented in MySQL: https://dev.mysql.com/worklog/task/?id=6936 : "If SELECT statement execution is completed before the timer expires then we cancel the timer" http://mysqlserverteam.com/server-side-select-statement-timeouts/ : "timer is cancelled if the SELECT statement completes within the time limit that was set" i interpret "statement execution is completed" above as "full fetch is done". PostgreSQL docs is very limited: https://www.postgresql.org/docs/9.9/static/runtime-config-client.html see "statement_timeout" I found no docs re. statement timeouts in Oracle Regards, Vlad ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, SlashDot.org! http://sdm.link/slashdot Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel
