How to convert from MySQL to Postgres

I have been using MySQL for probably as long as I could remember. For Bloglation, search capability is an important feature since it’s hard to browse each post one by one. I will probably implement tagging functionality, but even so, it’s important to be able to search the contents with a keyword(s). While Ultrasphinx works well, Heroku only supports WebSolr… I was using acts_as_ferret using /tmp for index files, but the problem using the /tmp directory is that ferret index files most likely to disappear at some point.

Then, I found out that Postgres supports full-text search and since Heroku uses Postgres, I could use other plug-ins like acts_as_tsearch or texticle for free. Free is important to me, since it’s not making any money.

Searching online, there are various ways to do it like Pivotal Labs’ script or Heroku’s Taps gem, but I wanted to do it in an old way like AEdifice to check everything is going alright at each step.

1. First thing to do is to backup MySQL

For me, it was important to backup preserving encoding, since it had many different languages. First I pulled db from Heroku thinking that I Continue reading

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Counting rows and modifying MySQL to work with Postgres or Heroku

Now I am moving on to Open Translation Project. I’ve done some translation work before, including one of Paul Graham’s essay – Why to not not start a startup. BTW, he finally made a link from the essay to my translation. I used Google Translate as base, but I couldn’t believe how bad the translation was. Yahoo’s Babel Fish was a little better, but not as much. That’s where I got the idea of creating this possibly massive project.

Anyhow, I wanted to find a way of selecting an article or blog that was translated the most. I had one model that stored basic information of original article/blog. Then its children are translations. So, I need to count rows of children with the same parent. In MySQL, I had the following statement in Rails.

@top_origs = OrigPost.find(:all,
                              :select => 'orig_posts.*, count(posts.id) as post_count',
                              :joins => 'left outer join posts on posts.orig_post_id = orig_posts.id',
                              :group => 'orig_posts.id',
                              :order => 'post_count DESC',
                              :limit => 5)

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