In Git you can add a submodule to a repository. This is basically a sub-repository embedded in your main repository. This can be very useful. A couple of usecases of submodules:
- Separate big codebases into multiple repositories.
| # | |
| # If all files excluded and you will include only specific sub-directories | |
| # the parent path must matched before. | |
| # | |
| /** | |
| !/.gitignore | |
| ############################### | |
| # Un-ignore the affected subdirectory |
| require 'minitest/spec' | |
| require 'minitest/autorun' | |
| module Helpers | |
| module Let | |
| def let(name, &blk) | |
| define_method name do | |
| @let_assigments ||= {} | |
| @let_assigments[name] ||= send(:"original_#{name}") |
| -- show running queries (pre 9.2) | |
| SELECT procpid, age(clock_timestamp(), query_start), 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(clock_timestamp(), query_start), usename, query | |
| FROM pg_stat_activity | |
| WHERE query != '<IDLE>' AND query NOT ILIKE '%pg_stat_activity%' |
| 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 |
| # encoding: utf-8 | |
| # Be sure to restart your server when you modify this file. | |
| # Add new inflection rules using the following format | |
| # (all these examples are active by default): | |
| # ActiveSupport::Inflector.inflections do |inflect| | |
| # inflect.plural /^(ox)$/i, '\1en' | |
| # inflect.singular /^(ox)en/i, '\1' | |
| # inflect.irregular 'person', 'people' | |
| # inflect.uncountable %w( fish sheep ) |