[Qt-interest] Qsqlite performance with multiple processes ?

[Stephen Collyer]

I was trying to see if I could feasibly replace a dependency on Mysql
by using sqlite. I suspect for my needs I could get away with it (very
few writes) but it would take me too long to rewrite the DB access
layer at the moment, so I won't be doing it anyway.

2009/3/31 Bill KING <bill.king at trolltech.com>

> Also, if you're looking at performance/locking from a multi-process
> situation, sqlite's not really the right tool for the job. A more full
> featured db engine would be recommended then. There are some
> zero-administration dbs out there, firebird's a good example.
>
> Stephen Collyer wrote:
> > I've taken a look at the Sqlite driver code in
> > sql/drivers/sqlite2/qsql_sqlite2.cpp
> > and I see the following code:
> >
> > 195     // keep trying while busy, wish I could implement this better.
> > 196     while ((res = sqlite_step(currentMachine, &colNum, &fvals,
> > &cnames)) == SQLITE_BUSY) {
> > 197         // sleep instead requesting result again immidiately.
> > 198 #if defined Q_WS_WIN32
> > 199         Sleep(1000);
> > 200 #else
> > 201         sleep(1);
> > 202 #endif
> >
> > This seems to imply that if a sqlite DB is locked for write by another
> > process,
> > then this code would block the calling process for 1 second before a
> > retry.
> > This would seem to make the sqlite driver unusable for any real
> > multiprocess
> > applications.
> >
> > So:
> >
> > 1) is my conclusion correct, or am I confused ?
> > 2) why has such a huge retry interval been chosen ?
> > 3) does anyone have real experience with qslite in a multiprocess app ?
> >
> > --
> >
> > Stephen Collyer
> > ------------------------------------------------------------------------
> >
> > _______________________________________________
> > Qt-interest mailing list
> > Qt-interest at trolltech.com
> > http://lists.trolltech.com/mailman/listinfo/qt-interest
> >
>
>
> --
> Bill King, Software Engineer
> Qt Software, Nokia Pty Ltd
> Brisbane Office
>
>


-- 
--

Stephen Collyer
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