slattery

CARTO at GIS Day - Yale

November 17, 2016

Michelle Ho, [email protected]

Mehak Sachdeva, [email protected], @MehakSachdeva_

This link is here: http://bit.ly/1117-yale

slattery

Extends Dynamic Classification of CartoDB Choropleth Map to include a legend. Makes use of a custom legend example and the cdb.geo.ui.Legend.Custom() method. Default CartoDB.css round bullets are overwritten to produce rectangles.

slattery

1. Delete all containers

    $ docker ps -q -a | xargs docker rm
   

-q prints only the container IDs -a prints all containers

Notice that it uses xargs to issue a remove container command for each container ID

2. Delete all untagged images

slattery

Leader Election With Ruby & PostgreSQL

The Problem

I have a table with millions of rows that needs processing. The type of processing is not really important for this article. We simply need to process some data with Ruby --or any other user-space programming language.

A Solution

slattery

// Handy plv8 console object (debugging)
var console = (function(){
    var columns = 100;
    function logString(level, str) {
        var chunk = str.substring(0, columns);
        var overflow = str.substring(columns);
        plv8.elog(level, chunk);
        if (overflow.length) logString(level, " | "+overflow);
    };

slattery

CREATE OR REPLACE FUNCTION plv8x.json_eval(code text) RETURNS plv8x.json AS $$
    return JSON.stringify(
        eval("(function(){return #code})").apply(this)
    );
$$ LANGUAGE plls IMMUTABLE STRICT;
CREATE OR REPLACE FUNCTION plv8x.json_eval(data plv8x.json, code text) RETURNS plv8x.json AS $$
    return JSON.stringify(
        eval("(function(){return #code})").apply(JSON.parse(data))
    );
$$ LANGUAGE plls IMMUTABLE STRICT;

slattery

/* public.plv8_startup()
 *
 *      Allow to have multiple per-schema plv8_init functions.
 *
 *   USAGE:
 *
 *      1. Add the following line to the end of your postgresql.conf file:
 *
 *          plv8.start_proc = 'public.plv8_startup'
 *

slattery

PL/v8

PL/v8 is a trusted procedural language that is safe to use, fast to run and easy to develop, powered by V8 JavaScript Engine.

Contents

Implemented features are as follows.

slattery

#! /bin/bash
sudo apt-get install npm

cd /var/django

npm install moment moment-timezone

sudo -u postgres psql -d template1 -c "create extension plv8;"

sudo -u postgres psql -d template1 << EOF

slattery

Listen / Notify for automatic object updates - pattern in postgreSQL Presented at the San Francsico PostgreSQL User Group Meetup 8/17/15

by Eric Eslinger [email protected] github.com/ericeslinger

This example uses listen/notify calls in PostgreSQL that trigger on row update to pass events from the database to a listening node.js web application that in turn uses socket.io to pass events