elisboa

#!/usr/bin/env bash
# ---
#!/bin/bash -x

echo -e "### WELCOME TO $0\n"

if [[ -z ${DEST_DIR} ]]
then
    TIMESTAMP=$(date +%s)
    echo -e "Setting destination dir as ${TIMESTAMP}"

saurabhnanda

Tuning ZFS + Postgres to outperform EXT4 + Postgres

Please refer to ZFS 2-3x slower than EXT4 to see how ZFS defaults + Postgres defaults severely underperform EXT4 defaults + Postgres defaults (and also to know more about the system on which these benchmarks were performed). This page documents how to tune ZFS + Postgres to give better performance for the tpcb-like benchmark.

BIG FAT WARNING

Please do not copy these settings blindly because I am myself not clear on why/how these settings had the impact they did. For example, I cannot explain why full_page_writes=off independently did not give that much boost, nor did an optimized PG configuration. However, putting both of them together gave a 2-4x boost compared to baseline numbers.

Benchmark results

phill-tornroth

"""
 Copies a parameter group in RDS, particularly useful for doing cross-region copies (which AWS documents,
 but doesn't actually support at the time of this writing.

 Usage:  python cp-parameter-group.py us-west-1:lookerdb-56 us-west-2:lookerdb-56
"""

import boto3
import sys

vinnix

$ ./bitcoin-qt --version
Bitcoin Core version v0.15.99.0-5180a86 (64-bit)
Copyright (C) 2009-2017 The Bitcoin Core developers

[vinnix@vnxsam bin]$ valgrind --leak-check=full --show-leak-kinds=all --leak-check=yes ./bitcoind  
==2817== Memcheck, a memory error detector
==2817== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.
==2817== Using Valgrind-3.12.0 and LibVEX; rerun with -h for copyright info
==2817== Command: ./bitcoind
==2817== 

silveraid

# Create a folder for our new root structure
$ export centos_root='/centos_image/rootfs'
$ mkdir -p $centos_root
# initialize rpm database
$ rpm --root $centos_root --initdb
# download and install the centos-release package, it contains our repository sources
$ yum reinstall --downloadonly --downloaddir . centos-release
$ rpm --root $centos_root -ivh centos-release*.rpm
$ rpm --root $centos_root --import  $centos_root/etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
# install yum without docs and install only the english language files during the process

anvk

--- PSQL queries which also duplicated from https://github.com/anvk/AwesomePSQLList/blob/master/README.md
--- some of them taken from https://www.slideshare.net/alexeylesovsky/deep-dive-into-postgresql-statistics-54594192

-- I'm not an expert in PSQL. Just a developer who is trying to accumulate useful stat queries which could potentially explain problems in your Postgres DB.

------------
-- Basics --
------------

-- Get indexes of tables

vinnix

CREATE OR REPLACE FUNCTION public.json_append(data json, insert_data json)
RETURNS json
IMMUTABLE
LANGUAGE sql
AS $$
    SELECT ('{'||string_agg(to_json(key)||':'||value, ',')||'}')::json
    FROM (
        SELECT * FROM json_each(data)
        UNION ALL
        SELECT * FROM json_each(insert_data)

wsdookadr

CREATE OR REPLACE FUNCTION public.json_append(data json, insert_data json)
RETURNS json
IMMUTABLE
LANGUAGE sql
AS $$
    SELECT ('{'||string_agg(to_json(key)||':'||value, ',')||'}')::json
    FROM (
        SELECT * FROM json_each(data)
        UNION ALL
        SELECT * FROM json_each(insert_data)

RobinCPC

How to use ConqueGDB in Vim

Install ConqueGDB in Vim

• Install Vim plugin manager Vundle
• Install ConqueGDB or
• Clone my vimrc

Debug C/C++:

Kartones

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)