Miles McGuire

Cache rules everything around me

[Miles McGuire @_minuteman3]

@samlambert Now that’s some serious IOPS

[Miles McGuire @_minuteman3]

@samlambert :feelsgoodman:

[Ruby on Rails @rails]

Intercom uses #Rails to enable hundreds of engineers to ship changes quickly without slow, centralized reviews. But running migrations across hundreds of tables and terabytes of MySQL data comes with real risks. In his #RailsWorld 2025 @_minuteman3 will share the changes they made to reduce risk and enable their engineers to safely move fast.
https://t.co/VVCbixXU2e @intercom

[Miles McGuire @_minuteman3]

@mhenrixon @ciaran_lee @qizler Worth a note here - with ignored columns we were listing off every column on the table in the query, the ignored columns had been dropped in many cases. So moving to select * was a pure saving, didn’t result in more data in the result set.

[Miles McGuire @_minuteman3]

@mhenrixon @ciaran_lee @qizler In the same cost saving exercise we elsewhere made big wins by *not* using select * and not loading big, heavy fields in contexts they’re not needed. Always need to consider context, measure, verify. select * is a good default though!

[Miles McGuire @_minuteman3]

@_exoconnor @ciaran_lee We also shaved off about half the query throughput - lots of redundant loads of the same object, easy to have it creep in over time in a big codebase. We already keep a copy of the object for every request, more on that here https://t.co/UoI4y7NVPC, so we just reused it!

[Miles McGuire @_minuteman3]

@_exoconnor @ciaran_lee This was an odd case - the table is super wide and serves upwards of 4 billion queries per day, basically the intercom god object. Column names are obviously all strings and many fields are just ints, tinyints, etc. things add up super fast at scale!

[Ciaran Lee @ciaran_lee]

The things that make a difference at scale are so wild.

Using ignored_columns in Rails results in SQL queries that list each column to be read, versus just "SELECT *". For tables with many columns, this meant we were sending ~20 TB of extra text to the database per day.

[Miles McGuire @_minuteman3]

@dihmeetree @samlambert @intercom I’m already there but haven’t been active in a while! I’ll make sure to say hi.

[Miles McGuire @_minuteman3]

@afomera I’m nervous too and sorry to be missing your talk - apparently we’re on at the same time! Best of luck - I’m sure you’ll be great.

[Miles McGuire @_minuteman3]

@rosapolis You’ll be great! Looking forward to the talk.

[DHH @dhh]

Okay, that's nuts. We sold out in 20 minutes!! I love this Rails Renaissance energy. I haven't felt this much excitement since the very earliest days of Rails. I can't wait to see all 1,000 lucky Rails World attendees in September.

[Miles McGuire @_minuteman3]

@_ginid My setup is similar if a bit less clean than yours - feels like there’s wires everywhere in this pic. But I’m still very happy with it!

[Miles McGuire @_minuteman3]

@_ginid Nice. Yeah I have an Audient id14, 58dB of gain over bus power but I’d need a cloud lifter for an sm7b all the same too.

[Miles McGuire @_minuteman3]

@ps5_ireland Got one. Thanks! After months of half assing it gave you a follow (+ notifications) and had one in less than 24 hours.

[Miles McGuire @_minuteman3]

@wrossmck We can call it “gravy”

[Miles McGuire @_minuteman3]

@_ginid I didn’t realise I was a
Coffee monster but based on this formula I am a double coffee monster.

[Miles McGuire @_minuteman3]

@sarahthenolan 57 point bump this year. Points sharply rose since we started college though, they were in the high 400s before we graduated. https://t.co/yPi8C87Dd1 funny to think I couldn’t get into our course now.

[Miles McGuire @_minuteman3]

@opinionatedpie Got one for the home office at the start of lockdown. 100% recommended.