How Many Grains of Sand are in a Pile

Everything you need to know about query planning can be understood from this query: SELECT * FROM xy WHERE y = 3 ORDER BY x Imagine we have two indexes, one ordered on y, and one ordered on x. Then two possible plans suggest themselves: Plan 1: scan the y index, restricting it to the values of y such that y = 3, then sort the result by x. Plan 2:...

Everything you need to know about query planning can be understood from this query: SELECT * FROM xy WHERE y = 3 ORDER BY x Imagine we have two indexes, one ordered on y, and one ordered on x. Then two possible plans suggest themselves: Plan 1: scan the y index, restricting it to the values of y such that y = 3, then sort the result by x. Plan 2:...

“This code’s no good,” says Pittsford, pointing at the screen: def update_and_get_balance(account, amount): database.debit(account, amount) return database.get_balance(account) Sol, the author of the code, peers over his shoulder and squints. “What’s wrong with it? It adds the amount, then gets back the new balance.” Pittsford shakes his...

I hope everyone had a good weekend. I went on a hike. It was great. Statistics One of my great school regrets, next to “taking three years of business classes,” is taking less statistics than I did, which was basically the bare minimum. It was, in fact the bare minimum: one probability class and one statistics class. In my defense, my probability...

I hope everyone had a good weekend. I went on a hike. It was great. Statistics One of my great school regrets, next to “taking three years of business classes,” is taking less statistics than I did, which was basically the bare minimum. It was, in fact the bare minimum: one probability class and one statistics class. In my defense, my probability...