Blake Miner's Blog

I'm pretty sure that if I've played 100 games and won exactly 1 of them, my winning percentage should be 1%. I might be wrong, though.  There is no rounding error when you do 1/100 * 100%.  Single-precision floating point number rounding error?  For some reason, I doubt it... Weird... and stupid... EDIT:  Wrote a C program to make sure that Microsoft's Minesweeper has a bug. $ cat main.c #include <stdio.h> int main() {         float x = 1.0 / 100 * 100;         printf("%f\n", x);         return 0; } $ gcc main.c; ./a.out 1.000000 ... Yep... sure does.

I recently asked  this question on StackOverflow  about how to join to a derived table using an index.  I found out that even if your derived table is generated with tables that use all of the proper indexes, and you try to join that derived table to a base table in your outer query, no indexes are used.  Ever... So, let's start with a contrived example (as we often do)... SELECT * FROM t1 JOIN (SELECT * FROM t2) AS derived_t2 ON t1.f1=derived_t2.f1; OK... so let me get this straight... even if t1.f1 and  t2.f1  are indexed, the join will still be a full table scan?  You betcha! Let me say that again...  whenever you write a subquery and try to join the derived table to your outer query tables, no indexes are ever used .  It's a full table scan. So, I think to myself... "Wow... so that's really stupid, actually... because I have tables that only have a few thousand rows in them, and the query performance is shit.  Like... over 2 seconds... terrible and u

If you're like me, then you are probably building web applications using Node.JS and MySQL (and maybe Redis, too).  If so, you're probably going to need transactions, and you've probably already noticed that the current version of node-mysql doesn't support transactions yet.  :( But that's OK because I have a solution for you.  Check out node-mysql-queues on github .  This project provides pretty good support for MySQL transactions with a fairly simple API.  There are a couple of things to remember, though.  For one, Node.JS is very "callback-centric," so when executing a series of queries, you would normally chain the queries together with a series of callbacks.  node-mysql sort of changes this model, by allowing you to place queries on a queue to be executed in order.  If you only care about doing something when all of your queries are done, you can simply put your callback in the final query.  node-mysql-queues allows you to do the same sort of thing