Dinh

Upgrading PostgreSQL on macOS

Tue, 22 May 2018 00:00:00 +0000

Follow these easy steps to upgrade your PostgreSQL without losing your data. For this post, I’m upgrading from 9.6.2 to 10.4!

1. Shut down PostgreSQL server

Assuming you are using Homebrew.

brew services stop postgresql

2. Update PostgreSQL

Use Homebrew to upgrade your PostgreSQL.

brew update && brew upgrade postgresql

3. Initialize a new data directory

To upgrade PostgreSQL and keep our old data, we need to migrate data from the old data directory to a new one. In order to do that, we need to create a new data directory first.

initdb /usr/local/var/postgres10.4 -E utf8

4. Migrate old data from old directory to new one

This can be done using pg_upgrade, we just need to specify the old data and executable directory (-d and -b), the new data and executable directory (-D and -B). Read more on pg_upgrade here.

pg_upgrade \
-d /usr/local/var/postgres \
-D /usr/local/var/postgres10.4 \
-b /usr/local/Cellar/postgresql/9.6.2/bin/ \
-B /usr/local/Cellar/postgresql/10.4/bin/ \
-v

5. Rename the data directory

PostgreSQL will look for postgres directory, so we just need to rename our new directory.

cd /usr/local/var
# rename the old postgres to postgres9.6.2 as back up
mv postgres postgres9.6.2
# rename our new data directory to postgres
mv postgres10.4 postgres

6. Start PostgreSQL back up

brew services start postgresql

With that, our PostgreSQL server should be live with all of our old data.

Find the parity outlier

Mon, 19 Sep 2016 00:00:00 +0000

To practice and sharpen my Javascript skill, I’ve been trying to do challenges at Codewars whenever I have time. Here is a challenge I’ve done recently, and how I solved it.

Challenge

You are given an array (which will have a length of at least 3, but could be very large) containing integers. The array is either entirely comprised of odd integers or entirely comprised of even integers except for a single integer N. Write a method that takes the array as an argument and returns N.

For example:

[2, 4, 0, 100, 4, 11, 2602, 36]

Should return: 11

[160, 3, 1719, 19, 11, 13, -21]

Should return: 160

Solution

function findOutlier(integers){
    var odds = [];
    var evens = [];

    for (var i = 0; i < integers.length; i++) {
      if (integers[i] % 2 === 0) {
        evens.push(integers[i]);
      } else {
        odds.push(integers[i]);
      }
    }

    if (odds.length > evens.length) {
      return evens[0];
    } else {
      return odds[0];
    }   
}

To get to the correct solution, first I need to split the array of integers into two arrays, an odds and evens array. Then I just compare the arrays’ length and return the first item of the shorter array. (You can also return the first item of the array with length equal to one since there is only one odd or one even integer).

Grails 3 setup on Mac OS X

Sat, 17 Sep 2016 00:00:00 +0000

I had to install Grails recently to work on one of my projects. This is the easiest way I’ve found to install Grails on your OS X.

Installing JDK

For Grails 3 you will need Java Development Kit (JDK) version 1.7 or above. Although Java SE Development Kit 7 is no longer getting an update from Oracle, you should install this kit since most Grails version work with it. Just download and run the installer.

After installation, you can verify by running:

java -version
# java version "1.7.*_*"

Installing Grails

The easiest way to install Grails on OS X is with SDKMAN!. Just run:

curl -s get.sdkman.io | bash

Follow the instructions on-screen to complete the installation. Open terminal and type the command:

source "$HOME/.sdkman/bin/sdkman-init.sh"

Then install the latest stable Grails:

sdk install grails

After installation is complete, check version with:

grails -version
# Grails version: 3.*.*

And that’s it. Unless you are working on a project that needs an older version of Grails, in that case, just install that version and use it by:

sdk install grails 2.4.4
sdk use grails 2.4.4
# For example, if you want to use Grails 2.4.4

My first post

Sun, 12 Jun 2016 00:00:00 +0000

My plan for this website is to:

Write down things that I find interesting or helpful.
Showcase my projects.
Experiment with ruby, jekyll and google’s amp.

I am currently in a full-stack web-dev program at galvanize, so I’m pretty busy, but I’ll try to post at least once a week.