Question

I'm hoping to find a way to sniff out potentially inefficient T-SQL within stored procedures, in this case detecting not just cursors in stored procedures, but preferably nested cursors.

With the script below based on sys.dm_sql_referenced_entities, from a given starting stored procedure I can see a recursive downstream call stack, including a column indicating whether the text CURSOR was found within the procedure definition.

This is helpful, but it isn't capable of telling me:

whether more than one cursor exists within a procedure
whether nested cursors are used (and of course, the truly perfect solution for that would also have to detect a call to stored procedure containing a cursor, from within a cursor)

Being able to do this I think is probably beyond the abilities of querying sys tables, and involves parsing the SQL itself - does anyone know of a technique or tool that could accomplish this, or perhaps an entirely different approach that could tell me the same information.

auto first = s.find("%24");               // Look for first %24
auto second = s.find("%24", first + 1);   // Look for second %24
std::cout << s.substr(first + 3, second - (first + 3)); // This is the substring you're looking for

EDIT: I am marking this as "solved" even though I think some improvements could be made to the below solution - I think it is "good enough" for most scenarios, but I think a fully recursive solution that can traverse an "infinitely" deep call chain is possible.

Answer 1

Maybe there is a more efficient way, but you could search the procedure code. It's not foolproof though in that it could get some false positives, but you shouldn't miss any. It doesn't ignore comments and variable names so it's quite possible to pick up some extra stuff.

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.POST;
import javax.ws.rs.Produces;
import javax.ws.rs.QueryParam;
import javax.ws.rs.core.Response;

I found a few nested cursors on our server I didn't know about. Interesting. :)

Possible to detect cursors (nested cursors) within T-SQL code?

1 个答案: