Re: [sqlite] Asynchronous I/O and shared cache

I meant the mutex that is a member of the BtShared struct (BtShared.mutex). Grabbed by the call to sqlite3VdbeMutexEnterArray() at the top of sqlite3VdbeExec() and not released until that function returns. Okay, now I see that and I don't like it at all. Of course it doesn't eliminate ability

Re: [sqlite] Asynchronous I/O and shared cache

According to the documentation : database connection in read-uncommitted mode does not attempt to obtain read-locks before reading from database tables as described above. This can lead to inconsistent query results if another database connection modifies a table while it is being read, but it

Re: [sqlite] Asynchronous I/O and shared cache

Thanks, I will try to use the shared cache with Async I/O Each shared-cache has its own mutex... So, does it possible to have more than one shared cache within a single process ? One shared cache by db ? -- View this message in context:

Re: [sqlite] Asynchronous I/O and shared cache

So, does it possible to have more than one shared cache within a single process ? Open the same database twice, using two different handles. At least I think it will work. Nope, it won't. That's the purpose of shared cache: if you open the same database several times with different

Re: [sqlite] Asynchronous I/O and shared cache

To be more precise I would like to parallelize writes operations on different tables, so potentially in different db (files). It's why I think about using multi databases (1 by table), the shared cache system and the asynchronized I/O.. So if a shared cache is shared accross different

Re: [sqlite] Asynchronous I/O and shared cache

Shared cache instance is created on file-by-file basis, i.e. if you open connections to file1.db and file2.db they will have different cache instances and any manipulations with these database files won't influence one another at all (any write operations can be executed in parallel). But if you

Re: [sqlite] Asynchronous I/O and shared cache

I'm confused according to Dan Kennedy : Each shared-cache has its own mutex. The mutex is held for the duration of each sqlite3_step() call. So the way you're defining it here, you can't have real concurrency when using shared-cache mode in any case. So, it's a little bit antagonist to say

Re: [sqlite] Asynchronous I/O and shared cache

I don't know what Dan meant by his words but AFAIK there's no mutex making exclusive grab of shared cache by sqlite3_step() call. There is only mutex making sqlite3_step() execution exclusive for connection object. Pavel On Wed, Nov 18, 2009 at 8:40 AM, presta harc...@gmail.com wrote: I'm

Re: [sqlite] Asynchronous I/O and shared cache

On Nov 18, 2009, at 10:03 PM, Pavel Ivanov wrote: I don't know what Dan meant by his words but AFAIK there's no mutex making exclusive grab of shared cache by sqlite3_step() call. There is only mutex making sqlite3_step() execution exclusive for connection object. I meant the mutex that is

[sqlite] Asynchronous I/O and shared cache

Hello, I'm wondering if shared cache and read uncommited isolation level with asyncronous I/O enabled is possible ? In sqlite3async.c I see a shared mutex between read and write operations, so I doubt that it is possible to have real concurrency between read and write... Regards -- View

[sqlite] Asynchronous I/O and shared cache

Hello, I'm wondering if shared cache and read uncommited isolation level with asyncronous I/O enabled is possible ? In sqlite3async.c I see a shared mutex between read and write operations, so I doubt that it is possible to have real concurrency between read and write... Regards -- View

Re: [sqlite] Asynchronous I/O and shared cache

On Nov 18, 2009, at 1:25 PM, presta wrote: Hello, I'm wondering if shared cache and read uncommited isolation level with asyncronous I/O enabled is possible ? I haven't tried, but I assume it is possible. The two features don't really interact. In sqlite3async.c I see a shared mutex