i'm getting an issue relating to the use of the random() function in a SQL query.
i run 2 PHP scripts very quickly (less than 1 second apart). they use an SQL query like SELECT * FROM table ORDER BY random() LIMIT 5; because the 2 scripts run so close together (in time) i get the same values as a result. this is somewhat difficult to isolate to prove its any one piece of technologies issue. i know at this point you'd like to dismiss it as PHP, PDO, the HTTPd, the browser, caches, anything but sqlite... the probability you are right is very high, agreed, however... after some investigation into how sqlite generates its first random numbers.. (the first after seeding), means the seed is effectively controlling the probability of getting a random number. the platform i'm using is Windows, and the seeding occurs in this function: static int winRandomness(); (somewhere in the windows specific src section of sqlite) in that function, is there any reason why the less volatile source of randomness is appended to the buffer first? wouldn't it be better to have the most volatile values first.. the QueryPerformanceCounter() is a very high frequency counter, it first would give this seed string more volatile bits at its beginning. I'm not sure if this will ultimately solve the problem from the 20th abstraction of my SQL query using random() but its a step in the right direction! when i run the same 2 scripts more than a second apart, i get random numbers. it has something to do with a clock value. i know its a big leap thru 20 abstraction layers from SQL random() to a win32 call deep in sqlite src code, but thats one of the places the clock count is used. _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
