MongoDB for Developers with Python Transcripts
Chapter: Welcome to the course
Lecture: Welcome!
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Hello and welcome to MongoDB for Python developers.
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Throughout this course, we're going to learn
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how to connect, model for and build applications with MongoDB,
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and we're going to do this with Python.
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We're going to look at the straightforward, lowest level way of doing things
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with PyMongo, and we're going to look at mapping classes
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through what's called an ODM, think orm for Mongo;
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an ODM to Mongo DB with Mongo Engine.
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And these come together to make a great combination.
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So let's begin by talking about document databases, how do they work?
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Well document databases in some ways
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are very much like standard relational databases,
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they have what you would think of as columns in that relational world,
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title, course id and duration in seconds here for example,
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but it also has nested data, so in a relational database
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we might have a lectures table that has
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some kind of foreign key constraint back to a chapter
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in this example we have on the screen here,
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but in fact in a relational database, we can embed those lectures
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inside of the chapter object, why is this good?
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Well, often, we spend so much time and energy
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building up an object hierarchy in our application
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and then tearing that apart into a bunch of little pieces
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what's called third normal form, basically normalizing our data
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in a relational database and then building a backup, taking it back apart
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and this object relational impedance mismatch
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makes it hard for us to reason about our code,
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it makes it a little bit less intuitive and so on.
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So with document databases, we can model our data
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the same way our application wants to use that data.
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We also have more flexibility in the schema,
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which means that deploying a new version of our application
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often does not require some kind of migration script and downtime,
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no, we just deploy the new version and the document database adapts to it.
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So document databases in my opinion are the best way to build applications,
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for the 80 percent case right, maybe you have some edge case
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where that doesn't make a lot of sense
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but most apps really benefit from using document databases.
