Thiago Gomes thiagomgo

PSQL

Magic words:

psql -U postgres

Some interesting flags (to see all, use -h or --help depending on your psql version):

-E: will describe the underlaying queries of the \ commands (cool for learning!)
-l: psql will list all databases and then exit (useful if the user you connect with doesn't has a default database, like at AWS RDS)

Moved to git repository: https://github.com/denji/nginx-tuning

NGINX Tuning For Best Performance

For this configuration you can use web server you like, i decided, because i work mostly with it to use nginx.

Generally, properly configured nginx can handle up to 400K to 500K requests per second (clustered), most what i saw is 50K to 80K (non-clustered) requests per second and 30% CPU load, course, this was 2 x Intel Xeon with HyperThreading enabled, but it can work without problem on slower machines.

You must understand that this config is used in testing environment and not in production so you will need to find a way to implement most of those features best possible for your servers.

normal(explicitly specified start AND end)

  curl -v -X GET -H "range: bytes=1-8" http://localhost:8080/bbb/test

specified ONLY start(end will be specified at the end of file)

  curl -v -X GET -H "range: bytes=10-" http://localhost:8080/bbb/test

specified ONLY one negative value(last N bytes of file will be retrieved)

Multiple SSH Keys settings for different github account

create different public key

create different ssh key according the article Mac Set-Up Git

$ ssh-keygen -t rsa -C "[email protected]"

	# Description:
	# Runs a command on hubot
	# TOTAL VIOLATION of any and all security!
	#
	# Commands:
	# hubot cmd <command> - runs a command on hubot host

	module.exports = (robot) ->
	robot.respond /CMD (.*)$/i, (msg) ->
	# console.log(msg)

	#!/bin/bash
	#
	# This script requires xpath to parse part of the dnscurl.pl output
	# on CentOS/RedHat/Amazon Linux:
	#
	# sudo yum install perl-XML-XPath
	#
	# also, dnscurl.pl (from http://aws.amazon.com/code/Amazon-Route-53/9706686376855511)
	# expects your secrets to be in ~/.aws-secrets
	# using a file format like this (from http://dmz.us/wp/wp-content/uploads/r53/aws-secrets.txt)

	rds-modify-db-parameter-group {param-group-name} \
	--parameters="name=character_set_server, value=utf8, method=pending-reboot" \
	--parameters="name=collation_server, value=utf8_general_ci, method=pending-reboot" \
	--parameters="name=tmp_table_size, value={DBInstanceClassMemory/16}, method=pending-reboot" \
	--parameters="name=max_heap_table_size, value={DBInstanceClassMemory/16}, method=pending-reboot" \
	--parameters="name=query_cache_type, value=1, method=pending-reboot" \
	--parameters="name=query_cache_size, value=131072, method=pending-reboot" \
	--parameters="name=table_open_cache, value=2500, method=pending-reboot" \
	--parameters="name=join_buffer_size, value={DBInstanceClassMemory/64}, method=pending-reboot" \
	--parameters="name=thread_cache_size, value={DBInstanceClassMemory/12582880}, method=pending-reboot" \

	echo "Removing requiretty"
	sed -i "s/^.*requiretty/#Defaults requiretty/" /etc/sudoers
	echo "Complete!"

	# to generate your dhparam.pem file, run in the terminal
	openssl dhparam -out /etc/nginx/ssl/dhparam.pem 2048