The Fermi Paradox

I read a rather interesting story concerning intelligent life

And I think I should post it here since, I really really enjoyed it.

The basic concept revolves around the great Italian Physicist called Enrico Fermi.

He lived during 1901 and 1954 made a lot of breakthroughs in modern physics (the only thing I remember from school though was the Fermi Level of ferrite metals — more here)

The Fermi level is the total chemical potential for electrons (or electrochemical potential for electrons) and is usually denoted by µ or EF

But this is irrelevant to what he said when he looked at the stars:

Yeah, summer, friends, camping, you will end up looking at them at some point…

Where is Everybody?

His point exactly. Based on many assumptions and theories, a simple paradox appears. We cannot see anyone apart from us in the universe (although our observation scope is rather small).

But according to this article, there is a high chance that some other life form ahead of us in technology and advancement that has colonized half his galaxy (which eventually must and will be visible? from us). This is explained thoroughly in the blog post.

But more on those thoughts to the following link :

The Fermi Paradox

What I also liked, and personally believe in part

is the saying by  Oxford University philosopher Nick Bostrom that “no news – is good news” 

 

Credit to P.K. – from the website : www.waitbutwhy.com 

WordPress SEO Sitemap and Heroku

Maybe you have read at a previous post about Heroku and WordPress

that we have been using PostgreSQL as a persistent storage for this current blog.

Aside from the problems with our hosting as it is, from the fact that we could not (and still cannot) run add-on PG4WP effectively with Heroku and WordPress, we found another rather serious problem.

Last night I was browsing Google’s Webmaster Tools

and I found out that my sitemap was not working properly.

Despite the fact that the link was loading (http://www.must-feed.com/sitemap_index.xml) if you got in and tried to load the posts sitemap (http://www.must-feed.com/post-sitemap.xml) it responded with a Not Found (404) page.

Post Sitemaps was Not Found (404)

Looking around the Heroku logs (in terminal write heroku logs) and I found out this really interesting error :

[error] WordPress database error ERROR: date/time field value out of range:
"0000-00-00 00:00:00"\nLINE 1: ...ssword = 'xxasdf' AND post_author
!= 0 AND post_date != '0000-00-0...\n
^ for query 
   SELECT COUNT(ID) FROM wp_posts
   WHERE post_status IN ('publish','inherit') AND
   post_password = '' AND post_author != 0 
   AND post_date != "0000-00-00 00:00:00" AND post_type = 'post' 
made by require('wp-blog-header.php'), wp, WP->main, 
WP->query_posts, WP_Query->query, WP_Query->et_posts, 
do_action_ref_array, call_user_func_array, WPSEO_Sitemaps->redirect, 
WPSEO_Sitemaps->build_sitemap, WPSEO_Sitemaps->build_post_type_map

I digged the code a bit and found out

that the problem was being caused by a query which was ran from WordPress SEO Yoast Plugin.

This query :

SELECT COUNT(ID) FROM $wpdb->posts {$join_filter} 
WHERE post_status IN ('publish','inherit') AND post_password = '' 
AND post_author != 0 AND post_date != "0000-00-00 00:00:00" AND post_type = %s

Had an invalid date for PostgreSQL database.

Not to mention that also, the guy who wrote PG4WP

the module that connects Postgres with WordPress (to be honest that is heavily resource consuming) had thought of sanitizing the query from these cases only at INSERTS:

$sql = str_replace( "0000-00-00 00:00:00", "'now() AT TIME ZONE 'gmt'", $sql);

EDIT: I found out that the above line while writing this post
was SQL Injecting the code which was escaped by  the back slashes of gmt and caused again Postgres to fail so I changed it properly. The ajax action of post creation was calling the wp_insert or wp_update method which in turn was trying to insert a new post. I will come back with another update since I cannot escape single quotes somehow…

And not on SELECTS and UPDATES.

So all I had to do was add a new line at 290

of file : /wp-content/pg4wp/driver_pgsql.php

$sql = str_replace("0000-00-00 00:00:00", "1977-01-01", $sql);

to sanitize the SELECT and the posts sitemap page (and xml) was being loaded properly:

EDIT: I have also found out that the same bug applies with the press_this.php functionality and you cannot use it (you need to sanitize this as well).

EDIT 2: There are numerous errors during rewrite from different modules. I will come up with my patches at a new github repo. Recently I found out that Jetpack also had a problem, more on that later.

Not Found error disappeared and the Posts entries were generated in the xml.
 Finally after all those I have to say

that the way WordPress uses the Database is the least RIDICULOUS.

Having worked with many systems on web, I suggest to move to a more database agnostic framework, such as pdo_mysql.

Upgrading to WordPress 3.9 in Heroku

As you may already know, our blog is using the WordPress Heroku PHP Buildpack.

Now, since April of 2014 Heroku has updated it’s buildpack to support officially PHP and their final version here. They have done a really fine job, compared to the old legacy buildpack which involved a custom build batch file, and a plain empty php file to procreate the Heroku Dyno to run the Apache process with php process. More details from this awesome guy, here : https://github.com/mhoofman/wordpress-heroku and the dyno changes here : https://github.com/xyu/wordpress-heroku .

Our current installation though uses also WordPress.

Since then WordPress has released some considerable updates, and we need to update to the newest version. So, doing the necessary process, downloading WP3.9.2 , extracting it to the current setup, committing, pushing to heroku master.

At first heroku fails. Since by default it uses the new buildpack and requires composer.json to exist, so as to run Composer and configure afterwards the PHP-Heroku-Buildpack. Now, that was my point of failure since I did not notice that you can keep the legacy buildpack (but hey, new is always better right?) and I agreed to take on the new one.

After following the guide here Getting Started With PHP ,  created a composer.json (currently empty since we did not require anything new) and modified Procfile since we needed to explicitly tell Heroku that we had a custom Apache configuration.

A custom Apache Configuration?

Aye. While on the old buildpack you could initialize the stack with php, some WordPress plugins (such as Jetpack, or Zip support) did multiple requests on the server (I assume Ajax ?) and Heroku did not support concurrent requests in the old buildpack. Zip required to include mod_deflate.so. So I found out this guy: https://github.com/xyu/ who wrote a custom script doing nothing more complex than including to the Apache conf his configuration which in turn enabled the concurrent requests. This file was being loaded at startup, when heroku dyno was running.

Searching the Heroku documentation

..and I found out that if you want to include a http.conf  file you have to do it somehow like this :
web: vendor/bin/heroku-php-apache2 -C apache_app.conf
by modifying the Procfile and inserting the custom config file.

Obviously that did not work.

There were warnings that stated that we could not declare ServerLimit inside the VirtualHost section. Which later on made more sense when I saw how New Heroku buildpack integrates apache…

Aside from that, in the Heroku Logs :

There were enough warnings (and a fatal) like these :
2014-04-30T17:59:48.184463+00:00 app[web.1]: [30-Apr-2014 17:59:47] WARNING: [pool www] child 48 said into stderr: "NOTICE: PHP message: PHP Warning: pg_query(): Query failed: ERROR: missing FROM-clause entry for table "session""
2014-04-30T17:59:48.184466+00:00 app[web.1]: [30-Apr-2014 17:59:47] WARNING: [pool www] child 48 said into stderr: "LINE 1: SELECT @@SESSION.sql_mode"
2014-04-30T17:59:48.184468+00:00 app[web.1]: [30-Apr-2014 17:59:47] WARNING: [pool www] child 48 said into stderr: " ^ in /app/wp-content/pg4wp/driver_pgsql.php on line 140"

I’m not a Postgres expert, I’m more familiar with MySQL so, I decided that I should install my blog locally.

Downloaded the Postgres dump, restored in local instance, along with the new buildpack, ran an apache instance, and voila another error:
LINE 1: SELECT @@SESSION.sql_mode
^ in /var/sites/example.com/www/wp-content/pg4wp/driver_pgsql.php on line 133
PHP message: PHP Fatal error: Call to undefined function wpsql_errno() in /var/sites/example.com/www/wp-content/pg4wp/core.php(32) : eval()'d code on line 1531"

That one was mitigated from these guys here : https://vitoriodelage.wordpress.com/2014/06/06/add-missing-wpsql_errno-in-pg4wp-plugin/

When I was sure that everything works as intended, I finally pushed again.

Nothing. 0. Actually 500:

500

Checked the logs and I was getting a VERY  descriptive message :
2014-22-11T03:17:49+00:00 heroku[router]: Error H12 (Request timeout) -> GET / dyno=web.1 queue= wait= service=30000ms status=503 bytes=0

This error was not helping at all. No matter what I tried after that, I kept receiving timeout, as if the php apache process was eating up all the resources of the dyno. Clearly something is very wrong…

Finally, I decided to use the standard legacy buildpack

And reverted everything, after upgrading to the new WordPress, migrating the database locally and updating the cloud afterwards.
I used the legacy buildpack by running in my local heroku env:
heroku config:set "BUILDPACK_URL=https://github.com/heroku/heroku-buildpack-php.git#legacy"

 

I have just recently found out that the guy who wrote the plugin connecting to Postgres (this guy: https://wordpress.org/plugins/postgresql-for-wordpress/ ) has recently stoped developing it. And later, (although I still have second thoughts on How hhvm is compatible with php 5.3 and more specifically 5.3 in WordPress) Xiao who migrated his blog to HH-VM/NginX/MySQL heroku build pack : https://github.com/xyu/heroku-wp .

As soon as I have updated I will gather results to see how it went.

EDIT: It looks like there is an update for PG4WP I have been missing. Trying it and letting you know…
EDIT2: Nothing. The process keeps hanging by returning :
←[0m at=error code=H12 desc="Request timeout" method=GET path="/" host=www.must-feed.com request_id=fcaa61c9-1bbf-48d2-9b3c-797ca14ffa58 fwd="192.168.84.223" dyno=web.1 connect=1ms service=30000ms status=503 bytes=1240