iphone - improve INSERT into sqlite - ios

Question

In my app, I need to INSERT multiple times some entry.
Each time, I am using this function:
- (int) insertFunction:(NSString *)stringa{
NSDate * start = [NSDate date];
sqlite3_stmt *statement;
NSString *file = [self getWritableDBPath];
if (sqlite3_open([file UTF8String] , &_database) == SQLITE_OK)
{
NSString *insertSQL = [NSString stringWithFormat:#"%#",stringa];
const char *insert_stmt = [insertSQL UTF8String];
sqlite3_prepare_v2(_database, insert_stmt, -1, &statement, NULL);
if (sqlite3_step(statement) == SQLITE_DONE)
{
//NSLog(#"Contact added");
} else {
NSLog(#"Failed to add contact");
}
sqlite3_finalize(statement);
}
sqlite3_close(_database);
int row_id = (int)sqlite3_last_insert_rowid(_database);
NSLog(#"SINGLE INSERT took: %f", -[start timeIntervalSinceNow]);
return row_id;
}
that took about 0.020 second, and make my app frezing about 5 second.
-EDIT- My getWritableDBPath is:
- (NSString *) getWritableDBPath {
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory , NSUserDomainMask, YES);
NSString *documentsDir = [paths objectAtIndex:0];
return [documentsDir stringByAppendingPathComponent:DATABASE_NAME];
}
What I can do to improve that time? For example, avoiding to open the data base each time? In this case how?
Thanks in advance

Answer 1

You might want to look at the closeDatabase call, if the version of SQLite you are using is new enough it will probably have placed your writes into the WAL and will be committing them into the main database. Although 5 seconds does seems quite slow.
For your other comment about leaving the database open, simply call the open one time only and hold onto the sqlite3* handle in a class variable, and then close it when the class gets dealloc'ed, you will see much better performance.