I'm creating a jewellery product catalogue application and I need to store properties for each product such as material, finishes, product type etc.
I've concluded that there needs to be a model for each property, mainly because things like material and finishes might have prices and weights and other things associated with them.
Which of the two options will be the most efficient way to store data and be scalable
Create a model PropertyMap that will map property types and IDs to a Product ID.
Create several other models such as ProductMaterial, ProductFinish etc that will made a property to a product
All the data needs to be searchable & filterable. The database will probably index around 10K products.
Open to other smarter ways to store this data as well!
As a rule of thumb, to get the most out of your database tools, it's best to normalize your data according to the typical SQL conventions. That means that a bunch of fields that have a one-to-one relationship with each other should be collected together into the same table. That way you can grab them all (and they're frequently needed together) with a simple and efficient query.
If you instead have to gather them up from some different organization, both you and the database will end up having to do a lot more work. It will scale poorly, both on the hardware and in your brain as you struggle to maintain and extend it.
Related
I am using Core Data to store objects. What is the most efficient possibility for me (i.e. best execution efficiency, least code required, greatest simplicity and greatest compatibility with existing functions/libraries/frameworks) to store different attribute values for each object depending on the context, knowing that the contexts cannot be pre-defined, will be legion and constantly edited by the user?
Example:
An Object is a Person (Potentially =Employer / =Employee)
Each person works for several other persons and has different titles in relation to their work relationships, and their title may change from one year to another (in case this detail matters: each person may also concomitantly employ one or several other persons, which is why a person is an employee but potentially also an employer)
So one attribute of my object would be “Title vs Employer vs Year Ended”
The best I could do with my current knowledge is save all three elements together as a string which would be an attribute value assigned to each object, and constantly parse that string to be able to use it, but this has the following (HUGE) disadvantages:
(1) Unduly Slowed Execution & Increased Energy Use. Using this contextual attribute is at the very core of my prospective App´s core function (so it would literally be used 10-100 times every minute). Having to constantly parse this information to be able to use it adds undue processing that I’d very much like to avoid
(2) Undue Coding Overhead. Saving this contextual attribute as a string will unduly make additional coding for me necessary each time I’ll use this central information (i.e. very often).
(3) Undue Complexity & Potential Incompatibility. It will also add undue complexity and by departing from the expected practice it will escape the advantages of Core Data.
What would be the most efficient way to achieve my intended purpose without the aforementioned disadvantages?
Taking your example, one option is to create an Employment entity, with attributes for the title and yearEnded and two (to-one) relationships to Person. One relationship represents the employer and the other represents the employee.
The inverse relationships are in both cases to-many. One represents the employments where the Person is the employee (so you might name it employmentsTaken) and the other relationship represents the employments where the Person is the Employer (so you might name it employmentsGiven).
Generalising, this is the solution recommended by Apple for many-many relationships which have attributes (see "Modelling a relationship based on its semantics" in their documentation).
Whether that will address all of the concerns listed in your question, I leave to your experimentation: if things are changing 10-100 times a minute, the overhead of fetch requests and creating/updating/deleting the intermediate (Employment) entity might be worse than your string representation.
I have a model Movie. That can have multiple Showtimes. Each Showtime is a pair of start and end times. Movies get saved in the database.
So although a Movie might have_many Showtimes, does that really need to be a model, or just a class, or some kind of custom tuple-like type?
I have seen where you can have a field with an array of values, but this would not be basic values as each value is a pair of times.
What is the best way to achieve this?
Showtimes should be a model, yes. Here are a few reasons:
Most relational databases don't natively support a tuple or array type.
What if you want to query movies occurring at a particular time? This would be difficult to do with a custom field, but would be relatively trivial with a separate table.
Most importantly, it enables better flexibility and extensibility through decreased coupling. For instance, does a showtime always exist exclusively to a movie? What if you want to extend your schema to add theatres where each theatre has many showtimes?
I have an app that consists mainly of restaurant model instances. One of the essential attributes for these restaurants is labeling the cuisine it falls under. I'm currently at odds with myself in regards to designing this. On one hand I thought of creating a Cuisine model and creating either a HMT or HABTM association between Restaurants and Cuisines.
More recently I came across this post which shows how to create a pre-defined set of attributes. To take the answer one step further I'm assuming (in my case) I'd add a string-based cuisine column to my restaurant model and setup a select box in my restaurant form that would save the selected value.
What I was wondering was what would be the most efficient way of doing this? The goal is to eventually be able to query restaurants based what cuisine(s) they fall under. I wasn't sure if a model would be the best choice due to it only serving as a join table in a sense with a name attribute. Wasn't sure if having this extra table for something so minute would be optimal.
On the other hand I didn't know if using YAML for this would be conducive since the values are essentially dummy strings with no tangible records on file like I'd have with a model instance. Can someone help me sort out this confusion?
There are many benefits of normalizing many-to-many relationships in the db. Here are some:
Searching, sorting, and creating indexes is faster, since tables are narrower, and more rows fit on a data page.
You can have more clustered indexes (one per table), so you get more flexibility in tuning queries.
Index searching is often faster, since indexes tend to be narrower and shorter.
More tables allow better use of segments to control physical placement of data.
You usually have fewer indexes per table, so data modification commands are faster.
Fewer null values and less redundant data, making your database more compact.
Triggers execute more quickly if you are not maintaining redundant data.
Data modification anomalies are reduced.
Normalization is conceptually cleaner and easier to maintain and change as your needs change.
Also, by normalizing you get the cleaner syntax and other infrastructure benefits from ActiveRecord, e.g.
cuisine.restaurants.where(city: 'Toledo')
I'm building a Ruby on Rails App for a business and will be utilizing an ActiveRecord database. My question really has to do with Database Architecture and really the best way I should organize all the different tables and models within my app. So the App I'm building is going to have a database of orders for an ECommerce Business that sells products through 2 different channels, a subscription service where they pick the products and sell it for a fixed monthly fee and a traditional ECommerce channel, where customers pay for their products directly. So essentially while all of these would be classified as the Order model, there are two types of Orders: Subscription Order and Regular Order.
So initially I thought I would classify all this activity in my Orders Table and include a field 'Type' that would indicate whether it is a subscription order or a regular order. My issue is that there are a bunch of fields that I would need that would be specific to each type. For instance, transaction_id, batch_id and sub_id are all fields that would only be present if that order type was a subscription, and conversely would be absent if the order type was regular.
My question is, would it be in my best interest to just create two separate tables, one for subscription orders and one for regular orders? Or is there a way that fields could only appear conditional on what the Type field is? I would hate to see so many Nil values, for instance, if the order type was a regular order.
Sorry this question isn't as technical as it is just pertaining to best practice and organization.
Thanks,
Sunny
What you've described is a pattern called Single Table Inheritance — aka, having one table store data for different types of objects with different behavior.
Generally, people will tell you not to do it, since it leads to a lot of empty fields in your database which will hurt performance long term. It also just looks gross.
You should probably instead store the data in separate tables. If you want to get fancy, you can try to implement Class Table Inheritance, in which there are actually separate but connected table for each of the child classes. This isn't supported natively by ActiveRecord. This gem and this gem might be able to help you, but I've never used either, so I can't give you a firm recommendation.
I would keep all of my orders in one table. You could create a second table for "subscription order information" that would only contain the columns transaction_id, batch_id and sub_id as well as a primary key to link it back to the main orders table. You would still want to include an order type column in the main database though to make it a little easier when debugging.
Assuming you're using Postgres, I might lean towards an Hstore for that.
Some reading:
http://www.devmynd.com/blog/2013-3-single-table-inheritance-hstore-lovely-combination
https://github.com/devmynd/hstore_accessor
Make an integer column called order_type.
In the model do:
SUBSCRIPTION = 0
ONLINE = 1
...
It'll query better than strings and whenever you want to call one you do Order:SUBSCRIPTION.
Make two+ other tables with a foreign key equal to whatever the ID of the corresponding row in orders.
Now you can keep all shared data in the orders table, for easy querying, and all unique data in the other tables so you don't have bloated models.
So this is probably a fairly easy question to answer but here goes anyway.
I want to have this view, say media_objects/ that shows a list of media objects. Easy enough, right? However, I want the list of media objects to be a collection of things that are subtypes of MediaObject, CDMediaObject, DVDMediaObject, for example. Each of these subtypes needs to be represented with a db table for specific set of metadata that is not entirely common across the subtypes.
My first pass at this was to create a model for each of the subtypes, alter the MediaObject to be smart enough to join into those tables on it's conceptual 'all' behavior. This seems straightforward enough but I end up doing a lot of little things that feel not so rails-O-rific so I wanted to ask for advice here.
I don't have any concrete code for this example yet, obviously, but if you have questions I'll gladly edit this question to provide that information...
thanks!
Creating a model for each sub-type is the way to go, but what you're talking about is multiple-table inheritance. Rails assumes single-table inheritance and provides really easy support for setting it up. Add a type column to your media_objects table, and add all the columns for each of the specific types of MediaObject to the table. Then make each of your models a sub-class of MediaObject:
class MediaObject < ActiveRecord::Base
end
class CDMediaObject < MediaObject
end
Rails will handle pulling the records out and instantiating the correct subclass, so that when you MediaObject.find(:all) the results will contain a mixture of instances of the various subclasses of MediaObject.
Note this doesn't meet your requirement:
Each of these subtypes needs to be represented with a db table for specific set of metadata that is not entirely common across the subtypes.
Rails is all about convention-over-configuration, and it will make your life very easy if you write your application to it's strengths rather than expecting Rails to adapt to your requirements. Yes, STI will waste space leaving some columns unpopulated for every record. Should you care? Probably not; database storage is cheap, and extra columns won't affect lookup performance if your important columns have indexes on them.
That said, you can setup something very close to multiple-table inheritance, but you probably shouldn't.
I know this question is pretty old but just putting down my thoughts, if somebody lands up here.
In case the DB is postgres, I would suggest use STI along hstore column for storing attributes not common across different objects. This will avoid wasting space in DB yet the attributes can be accessed for different operations.
I would say, it depends on your data: For example, if the differences between the specific media objects do not have to be searchable, you could use a single db table with a TEXT column, say "additional_attributes". With rails, you could then serialize arbitrary data into that column.
If you can't go with that, you could have a general table "media_objects" which "has one :dataset". Within the dataset, you could then store the specifics between CDMediaObject, DVDMediaObject, etc.
A completely different approach would be to go with MongoDB (instead of MySQL) which is a document store. Each document can have a completely different form. The entire document tree is also searchable.