On Wed, 14 Sep 2016 16:27:37 +0530
SinhaK <sinha.shailend...@gmail.com> wrote:

> strlen(MyString.str().c_str())

BTW, as a matter of style, 


gets you to the same place sooner.   

> MyString<<"select TokenNo,Price ,sum(QTY) from 'Stream0' where 
> TokenNo=?1 and Side=66 group by Price order by Price desc limit 5";

You should group by TokenNo, Price.  You should not have 


in single quotes; that makes it a string.  

But I agree with Teg: SQLite is providing you with transactions you
don't need, and puts an interpreted language exactly where you don't
want it: in a performance-critical spot.  The C++ standard library has
all the bits you need, and is almost as convenient to use.  

You have only one table, and probably just a few simple queries.
std::set gives you lower_bound and upper_bound.  Hand those two
iterators to std::accumulate, and you have GROUP BY.  Call that for 5
prices.  Not very much code, and I bet 100x faster than SQL.  If more
than one thread is updating the table, obviously protect your set with
a mutex.  


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