Hi,
We were looking at the ways we can optimize our application. Our app does a
simple sqlite3_exec and sends the callback as below. The data is just a
map<string, vector<string> >
int sqlite3TableCallback(void* data, int ncols, char** values, char** headers)
{
map<string, vector<string> >& table = *(( map<string,
vector<string> >*) data);
for (int i = 0; i < ncols; i++)
{
if(values[i])
table.Data[headers[i]].push_back(string(values[i]));
else
table.Data[headers[i]].push_back(string());
}
return 0;
}
Here, we wanted to optimize the string construction of string in
table.Data[headers[i]]. We were happy to notice that the headers were pointing
to the same address, hence we are planning to enhance the callback data so that
it can track map<char*, string>, and then in the table.Data[headers[i]] we can
pass reference to the string preventing its construction and destruction.
Agreed, there will be another look-up in the map, for char* to string.
Well, the bottom line, is it safe to assume that char** headers will be
pointing to the same address through out the query (i.e. each time callback is
called for a matching row).
Regards,
Prakash Bande
Altair Engg. Inc.
Troy MI
Ph: 248-614-2400 ext 489
Cell: 248-404-0292
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