"Dave Gierok" <[EMAIL PROTECTED]> wrote: > I am developing a game on Xbox360 using Sqlite for a lot of our data > manipulation.
That's good to know. I'll be shortly adding a Microsoft logo to the image of companies and projects using SQLite at http://www.sqlite.org/google-talk-slides/logos4.gif :-) > We use the ':memory:' functionality to create our DB in > RAM, because we need our DB manipulations to be very fast - we can't > afford for our queries to cause seeks/loads on the DVD. > > This works very well for us with one exception: It takes a long time to > load the DB. Since we need the DB to be in memory, we create an empty > ':memory:' DB, then load up a file which contains all the SQL (CREATE > TABLE, INSERT INTO) we need to create our tables and execute them on the > memory-DB. This process currently takes 10 seconds (all running the SQL > statements to create the tables), which is not acceptable for our game. > The code below should do what you need. First create your :memory: database. Then open the file that contains the initialization database. Then read a chunk of the file and write that same chunk into the :memory: database by calling sqlite3_raw_write(). The code below messes with internal data structures of SQLite and is not guaranteed to work in future SQLite releases. So beware. /* ** This routine is called to write data directly into the database image ** (presumably taken from a database file created externally). ** ** The database from which the supplied data is taken must have a page-size ** equal to the value of the SQLITE_DEFAULT_PAGE_SIZE macro this file is ** compiled with. */ int sqlite3_raw_write( sqlite3 *db, int nData, int iOffset, unsigned const char *zData ){ Pager *pPager; int pageSize; /* Copy of pPager->pageSize */ int psAligned; /* Copy of pPager->psAligned */ int n; /* Remaining bytes to copy into database pages */ unsigned const char *z; /* Bytes to copy into database pages */ int iPage; /* Page number to copy into */ int iOff; /* Offset on iPage to write to */ int rc = SQLITE_OK; /* Offset on iPage to write to */ unsigned char *p1 = 0; /* First page of database */ assert( db ); assert( nData>=0 ); assert( iOffset>=0 ); assert( db->aDb[0].pBt ); assert( zData || nData==0 ); pPager = sqlite3BtreePager(db->aDb[0].pBt); psAligned = pPager->psAligned; pageSize = pPager->psAligned; z = zData; n = nData; /* This routine may not be used if any statements or a transaction are ** currently active. If this is not the case and we can proceed, grab a ** reference to page 1 and hold it until the end of this function so that ** the transaction is not rolled back because the page reference count ** reaches zero. */ if( pPager->nRef>1 ){ rc = SQLITE_MISUSE; }else{ rc = sqlite3pager_get(pPager, 1, (void **)&p1); } iPage = (iOffset / psAligned) + 1; iOff = (iOffset % psAligned); while( n>0 && rc==SQLITE_OK ){ int bytes; /* Number of bytes to write */ unsigned char *p = 0; /* Page iPage */ bytes = pageSize-iOff; bytes = (bytes<n)?bytes:n; /* Retrieve the page, set it to writable and copy the data to it. The ** first sqlite3pager_write() call starts a new transaction, which is ** committed at the end of this routine. */ if( SQLITE_OK==(rc=sqlite3pager_get(pPager, iPage, (void **)&p)) && SQLITE_OK==(rc=sqlite3pager_write(p)) ){ memcpy(&p[iOff], z, bytes); } if( p ){ sqlite3pager_unref(p); } bytes += (psAligned-pageSize); n -= bytes; z += bytes; iOff = 0; iPage++; } if( rc==SQLITE_OK ){ rc = sqlite3pager_commit(pPager); } if( p1 ){ sqlite3pager_unref(p1); } sqlite3Error(db, rc, 0); return sqlite3ApiExit(db, rc); } -- D. Richard Hipp <[EMAIL PROTECTED]>
