DateTime, Timestamp, Time and Date in Rails

Learn about key differenece between DateTime, Timestamp, Time and Date in Rails
31 October 2017   2170

The difference between different date/time formats in ActiveRecord have little to do with Rails and everything to do with whatever database you're using.

Using MySQL as an example (if for no other reason because it's most popular), you have DATEDATETIMETIME and TIMESTAMP column data types; just as you have CHARVARCHARFLOATand INTEGER.

So, main differences: DATE only stores a date, TIME only stores a time of day, while DATETIME stores both.

The difference between DATETIME and TIMESTAMP is a bit more subtle: DATETIME is formatted as YYYY-MM-DD HH:MM:SS. Valid ranges go from the year 1000 to the year 9999 and everything in between. While TIMESTAMP looks similar when you fetch it from the database, it's really a just a front for a unix timestamp. Its valid range goes from 1970 to 2038. The difference here, aside from the various built-in functions within the database engine, is storage space. Because DATETIMEstores every digit in the year, month day, hour, minute and second, it uses up a total of 8 bytes. As TIMESTAMP only stores the number of seconds since 1970-01-01, it uses 4 bytes.

You can read more about the differences between time formats in MySQL here.

In the end, it comes down to what you need your date/time column to do. Do you need to store dates and times before 1970 or after 2038? Use DATETIME. Do you need to worry about database size and you're within that timerange? Use TIMESTAMP. Do you only need to store a date? Use DATE. Do you only need to store a time? Use TIME.

Having said all of this, Rails actually makes some of these decisions for you. Both :timestamp and :datetime will default to DATETIME, while :date and :time corresponds to DATE and TIME, respectively.

Ruby Meditation #22 in Dnipro

Meditation will be held on May 19, at Parle, Troitska St, 21 g, Dnipro
27 April 2018   533

On Ruby Meditation #22 you will hear about helpful tools and gems for building Slack apps, examples how to build functional architecture with ruby, which place takes Ruby on Rails among alternatives in 2018 and much more.

Come and get your portion of good mood, knowledge, professional communication and tasty lunch :)

Share your positive experience and best practices on this Ruby Meditation #22. If you have any work issues you cannot solve, our community will gladly help you to find the best way out in live discussion at Lightning talks session. You may also try yourself as a speaker with a short 5-10 mins talk. Fill in this form.

Programme

Anna Shcherbinina

Topic: "Docker + GPU. Not about mining."

Anna Shcherbinina
Anna Shcherbinina

Just before Christmas we launched a new body-measurement feature for our shapify.me project. A person goes into the 3D booth, gets scanned, and the body-measurements are calculated with the 3D scan data. We couldn't avoid using a GPU with these calculations.

How to install this branch of processing into our elegant scaling pipeline? When you're dealing with 3D scans you should remember two things: it's expensive and time-consuming. By the way, its workload fluctuates throughout the days. The easiest solution for us was to use Docker.

This speech is not about mining, but the most helpful articles for us were ones such as "Building your own mining farm". That's because we use quite a similar infrastructure.

GPU, Docker, scaling. What we achieved, where we failed, and what it became of it in the end is all included in my speech.
 

Anna Shcherbinina

Head of Web, Artec3D, Luxembourg

Kirill Shevchenko

Topic: "Building Slack apps with Ruby."

Kirill Shevchenko
Kirill Shevchenko

Overview of Slack APIs. Their features, restrictions, and bottlenecks. Which API is right for you? Helpful tools and gems for building Slack apps.
 

Kirill Shevchenko

Ruby/JS Developer

Valentine Ostakh

Topic: "Functional objects in Ruby: new horizons "

Valentine Ostakh
Valentine Ostakh

Overview of functional programming concepts.  What is functional objects. Examples how to build functional architecture with ruby.
 

Valentine Ostakh

Ruby/JS Developer

Leonid Shevtsov

Topic: "A polyglot's view of Ruby on Rails"

Leonid Shevtsov
Leonid Shevtsov

Nowadays, it's hip to switch from Rails to other languages and frameworks. Leonid, too, has abandoned Rails, played the field a bit, and has come around to occasionally but consistently picking Rails for some projects. What's the modern reason to use Rails? What are the strengths of Ruby and Rails and how to build upon them? When you should really jump to some other platform? Let's answer these questions in a true Ruby meditation.
 

Leonid Shevtsov

Systems Architect

Oleksii Dashkevych

Topic: "Project development - preparing hell dish together"

Oleksii Dashkevych
Oleksii Dashkevych

The recipe is averaged, because of many variations. We take some Ruby code and add Rails magic, Postgresql on top. Add Docker for viscosity. Then put this on AWS EBS pan and start frying. It's all roasted until burning deadlines and generously watered with bugs, serves to the customer. They start eating. Eat and whisper: “This is an awesome product!”. At the same time, he forehead is sweating. Kindly offer to fix bugs, but we refuse and put them in JIRA. Do I need to talk about what kind of feedback comes then? Tasks with such recipes, that double estimated.
 

Oleksii Dashkevych

Ruby/JS Developer

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