durango

Mozilla Public License, version 2.0

1. Definitions

1.1. "Contributor"

     means each individual or legal entity that creates, contributes to the
     creation of, or owns Covered Software.

1.2. "Contributor Version"

durango

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.

durango

Go Cheat Sheet

Index

1. Basic Syntax
2. Operators

• Arithmetic
• Comparison
• Logical
• Other

3. Declarations

durango

Go Cheat Sheet

Index

1. Basic Syntax
2. Operators

• Arithmetic
• Comparison
• Logical
• Other

3. Declarations

durango

WAL-G PITR

This gist summarises a way to simulate point-in-time recovery (PITR) using WAL-G. Most of the material is adapted from Creston's tutorial.

Setup

First we initialize a database cluster

pg_ctl init -D cluster

durango

import React, { useReducer, useEffect, useRef } from 'react';
import firebase from 'firebase/app';
import equal from 'deep-equal';

function filterKeys(raw, allowed) {
  if (!raw) {
    return raw;
  }
  let s = new Set(allowed);
  return Object.keys(raw)

durango

-- 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%' 

durango

package main

import (
	"fmt"
)

type MyEmitter map[string]chan string

func main() {
	myEmitter := MyEmitter{}

durango

Neo4j directed path through multiple relationships with property filter

From Stackoverflow Question

Being new to Cypher and Neo4j, I am having trouble constructing my query for my use-case. I am building a simple ACL (access control list) and am looking for a path through permission relationships an up a hierarchy as well. A picture may better explain it:

Key:

durango

List of Cryptocurrency exchanges with Websocket API

• binance

• bitfinex

• bittrex