Kestrer

How to Write Hygienic Rust Macros

Macro hygiene is the concept of macros that work in all contexts; they don't affect and aren't affected by anything around them. Ideally all macros would be fully hygienic, but there are lots of pitfalls and traps that make it all too easy to accidentally write unhygienic macros. This guide attempts to provide a comprehensive resource for writing the most hygienic macros.

Understanding the Module System

First, a little aside on the details of Rust's module system, and specifically paths; it is

ian-whitestone

Presto Specific

• Don’t SELECT *, Specify explicit column names (columnar store)
• Avoid large JOINs (filter each table first)
  • In PRESTO tables are joined in the order they are listed!!
  • Join small tables earlier in the plan and leave larger fact tables to the end
  • Avoid cross joins or 1 to many joins as these can degrade performance
• Order by and group by take time
  • only use order by in subqueries if it is really necessary
• When using GROUP BY, order the columns by the highest cardinality (that is, most number of unique values) to the lowest.

santisbon

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baryon

adapter:
  #ss代理， 在国内购买一台云服务器，安装好ShadowSocks代理服务器，iPhone版安装Wingy APP （SMART LIMITED的深蓝紫色免费版）。使用的本文的自定义配置YAML
  - id: proxyAdapter
    type: ss
    #修改ss_host为服务器地址
    host: ss_host
    #修改ss_port为端口号
    port: ss_port
    #修改ss_password为密码
    password: ss_password

joyrexus

collapsible markdown?

CLICK ME

yes, even hidden code blocks!

print("hello world!")

KodrAus

Profiling performance

Using perf:

$ perf record -g binary
$ perf script | stackcollapse-perf.pl | rust-unmangle | flamegraph.pl > flame.svg

NOTE: See @GabrielMajeri's comments below about the -g option.

johnwheeler

Flask-Ask Live Presentation Over the Web

The creator of Flask-Ask will show your group of 3 or more how easy it is to program the Amazon Echo with Python!

You ask 'Alexa' to play songs, get the weather, and report scores. Those 'skills', as they're called, have an open API for building conversational apps. That API is the Alexa Skills Kit, and Flask-Ask is a Python framework that makes working with it easy.

Developing with Flask-Ask is fun. It's a novel experience to write and test conversational code,

bastman

Docker - How to cleanup (unused) resources

Once in a while, you may need to cleanup resources (containers, volumes, images, networks) ...

delete volumes

// see: https://github.com/chadoe/docker-cleanup-volumes

$ docker volume rm $(docker volume ls -qf dangling=true)

$ docker volume ls -qf dangling=true | xargs -r docker volume rm

vasanthk

System Design Cheatsheet

Picking the right architecture = Picking the right battles + Managing trade-offs

Basic Steps

1. Clarify and agree on the scope of the system

• User cases (description of sequences of events that, taken together, lead to a system doing something useful)
  • Who is going to use it?
  • How are they going to use it?

jloveland

# Reference:
https://www.cloudgear.net/blog/2015/5-minutes-kubernetes-setup/

# install homebrew and cask
ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"

# install virtualbox
brew cask install virtualbox

# install dockertoolbox