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Now before exploring all these exciting types you saw in the previous slide, there is something important

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I need to highlight about numbers in the mongo shell.

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The mongo shell is based on Javascript, it's basically implemented in javascript

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you could say and therefore it follows some default javascript just has well inherit and one of that

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is that a number like 64 by default in javascript is not stored as an integer or treated as an integer

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but as a 64 bit float,

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so as a double. This is just a default in Javascript,

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so this number and this number are essentially the same in Javascript, behind the scenes they will be

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stored in something like this, with some kind of imprecision at some point, doesn't have to be a two

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at exactly this place but it will have some imprecision because it's a 64 bit float.

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This is how it works in javascript and therefore, if I just use a dummy collection, num test, whatever

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you want to use and then insert one value in there with A1,

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since I'm doing this from within the mongo shell, this one will be inserted into mongodb as a double

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not as this 128 bit high precision decimal,

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we'll have a look at that in this module

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but as a 64 bit float double.

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So this is how it will be inserted,

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it will not be inserted as an int 32 and I highlight this because this is really just inherent to the mongo

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shell because it's based on Javascript, you would face the exact same behavior when working with nodejs

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in the mongo driver there

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but for other languages and their drivers, let's say for python, this will differ. In Python, a value like

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this would be an integer and a value like this would be a float,

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so python does differentiate and therefore there, this would be inserted as a double into mongodb,

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so will be stored as a normal double in the database,

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this would be inserted as an int 32

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and this will be important to understand.

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Now I will later in the from shell to driver module show you how to write code with a

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mongodb driver in a real application and I will show you how you can get a feeling for what is

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supported,

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which types do I have to convert

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but you also always have to know the language you're working in and you have to know the defaults for

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this language. Does it differentiate between integers and doubles?

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If yes, what is the default integer,

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is it an int 32

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and then you will know do I need to convert it as we will do it in this module

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because for the shell which is based in javascript, we will have to explicitly create an int 32 because

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this is not one as I just explained, for other languages this will not be required

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and this is just one important thing you have to keep in mind

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for the language you're working with. The from shell to driver module should make it clearer how you can

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write code and how you can create

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let's say that 64 bit int in your driver code.

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So you will learn that later in the course

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no worries,

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I just want to highlight that the default which gets written into mongodb

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does not depend on mongodb

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but on the client you're using, in the shell it's based on Javascript,

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so the default is the 64 bit double.