Re: often PREPARE can generate high load (and sometimes minutes long unavailability)

Hello

I got a example of code, that generate relatively high load with minimal connections.

This code is +/- bad - it repeatedly generate prepare statement, but somewhere uses prepared statements as protections against SQL injections and they can use same use case.

Pseudocode (I can send a test case privately):

Script a:

 -- A,B are in RAM

  for i in 1 .. N loop

    insert into A values();

    for j in 1 .. M loop

      insert into B values();

    end loop;

  end loop;

Script b:

-- query is extremely fast - returns 0 or 1 rows usually

40 threads execute

while true loop

  pr = PREPARE SELECT * FROM A LEFT JOIN B ON ..

  EXECUTE pr(...)

  sleep(10 ms)

end loop