Dan, Can you explain to me how within the context of the test_server.c code that the sqlite3_enable_shared_Cache will improve concurrency, for a single DB file access? I just don't see where any concurrency is gained. Sure maybe some memory savings. But I must be brain dead, because I don't see how it could improve concurrency given that a single thread is used to perform db access. And all clients are queued and blocked upon the single threads message queue. Thanks, Ken
Dan Kennedy <[EMAIL PROTECTED]> wrote: > Which in that case whats the point of a shared cache? > What is it shared against, since all threads must send > data to the shared server anyways and none may access > it concurrently. The idea is to have a single cache shared accessed by more than one logical connection (read: more than one transaction context). It's meant to reduce IO and memory usage in the case that a process opens more than one connection to the same database file. It's quite a specialised feature. Only really useful if you are implementing an embedded server. Dan > One thing that Other database engines do is allow read and writes to occur > without blocking. That is a Reader never blocks a writer and a Writer never > blocks a reader. SQLITE does not do this, Only a single writer or Multiple > readers, but not both concurrently. > > I'm not trying to pick on sqlite, just pointing out that it really doesn't > perform multi threading or even conncurrent access very well in a read/write > environment. Read Only, its great. Single threaded Read/Write ... Very good > as well. > > Regards, > Ken > > > > > > Doug Nebeker wrote: > > Yes I did the same experiment with a lock that made > thread A wait > > > until B was finished. So actually only one thread can be active at > the time. > > > I don't see how the outcome of this experiment can be of any > > > interest, as there is no time reduction any longer. But your guess > is > > > right that, it works. > > > >How would multiple threads be faster than a single one when you are > accessing a single resource? > > Assumably the thread that is accessing the database either spends some > time gathering data to write > or processing data it read. The single resource isn't in use during > that time. > > This email was sent to you by Reuters, the global news and information > company. > To find out more about Reuters visit www.about.reuters.com > > Any views expressed in this message are those of the individual sender, > except where the sender specifically states them to be the views of Reuters > Limited. > > Reuters Limited is part of the Reuters Group of companies, of which Reuters > Group PLC is the ultimate parent company. > Reuters Group PLC - Registered office address: The Reuters Building, South > Colonnade, Canary Wharf, London E14 5EP, United Kingdom > Registered No: 3296375 > Registered in England and Wales > > > > ----------------------------------------------------------------------------- > To unsubscribe, send email to [EMAIL PROTECTED] > ----------------------------------------------------------------------------- > > ----------------------------------------------------------------------------- To unsubscribe, send email to [EMAIL PROTECTED] -----------------------------------------------------------------------------
