On: WebSockets cost us $1M on our AWS bill

[antisthenes]

99% of the time, it's either a quadratic (or exponential) algorithm or a really bad DB query.

[dd82 → antisthenes]

can also be a linear algorithm that does N+1 queries. ORMs can be very good at hiding this implementation detail

[Quekid5 → dd82]

> a linear algorithm that does N+1 queries.

That's what quadratic means.

[sgerenser → Quekid5]

Typically implemented accidentally: https://www.tumblr.com/accidentallyquadratic

[nwellnhof → Quekid5]

No, N+1 is still linear.

[jon_richards → Quekid5]

Not really what they're talking about https://stackoverflow.com/questions/97197/what-is-the-n1-sel...

[DylanSp → antisthenes]

It wasn't a financial cost, but the biggest single performance improvement I've seen firsthand came from optimizing a SQL query. One of our Professional Services people had written a query that did repeated self-joins on a fairly large table, which took ~15 minutes to run. A DBA-turned-dev on our team rewrote it using MSSQL's PIVOT operator, and the query started executing in less than a second.