pechorin

tmux cheatsheet

As configured in my dotfiles.

start new:

tmux

start new with session name:

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Frontend Development

Attention: the list was moved to

https://github.com/dypsilon/frontend-dev-bookmarks

This page is not maintained anymore, please update your bookmarks.

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Finally, Simple Form support Boostrap 3. 👏

But I found it still dosen't support some components in Bootstrap 3. Or may be in the future. But I can't wait, so I find a solution to support them. It was inspired by heartcombo/simple_form#531 (comment) .

This is a final solution and I used in my project.

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-- show running queries (pre 9.2)
SELECT procpid, age(query_start, clock_timestamp()), usename, current_query 
FROM pg_stat_activity 
WHERE current_query != '<IDLE>' AND current_query NOT ILIKE '%pg_stat_activity%' 
ORDER BY query_start desc;

-- show running queries (9.2)
SELECT pid, age(query_start, clock_timestamp()), usename, query 
FROM pg_stat_activity 
WHERE query != '<IDLE>' AND query NOT ILIKE '%pg_stat_activity%' 

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YARD CHEATSHEET http://yardoc.org

cribbed from http://pastebin.com/xgzeAmBn

Templates to remind you of the options and formatting for the different types of objects you might want to document using YARD.

Modules

Namespace for classes and modules that handle serving documentation over HTTP

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-- Order by one indexed column (FAST)
newsdesk_production=# explain analyze select * from pressreleases order by published_at DESC limit 100;
                                                                                   QUERY PLAN                                                                                    
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Limit  (cost=0.00..249.91 rows=100 width=1207) (actual time=26.070..716.453 rows=100 loops=1)
   ->  Index Scan Backward using pressreleases_published_at_index on pressreleases  (cost=0.00..964766.62 rows=386042 width=1207) (actual time=26.067..716.343 rows=100 loops=1)
 Total runtime: 716.709 ms
(3 rows)

- Order by two separately indexed columns (SLOW)

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Types of index scans

Indexes

Sequential Scan:

• Read every row in the table
• No reading of index. Reading from indexes is also expensive.

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Pry Cheat Sheet

• Youtube Tutorial 2013

Command Line

• pry -r ./config/app_init_file.rb - load your app into a pry session (look at the file loaded by config.ru)
• pry -r ./config/environment.rb - load your rails into a pry session

Debugger

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Latency Comparison Numbers (~2012)
----------------------------------
L1 cache reference                           0.5 ns
Branch mispredict                            5   ns
L2 cache reference                           7   ns                      14x L1 cache
Mutex lock/unlock                           25   ns
Main memory reference                      100   ns                      20x L2 cache, 200x L1 cache
Compress 1K bytes with Zippy             3,000   ns        3 us
Send 1K bytes over 1 Gbps network       10,000   ns       10 us
Read 4K randomly from SSD*             150,000   ns      150 us          ~1GB/sec SSD

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require 'logger'

module Dim
  class Logger < ::Logger
    def initialize(*)
      super
      @formatter = NoTimestampFormatter.new
    end
  end