How to Query this in MongoDB?

Question

My items store in MongoDB like this :

{"ProductName":"XXXX",
   "Catalogs" : [
    {
        "50008064" : "Apple"
    },
    {
        "50010566" : "Box"
    },
    {
        "50016422" : "Water"
    }
]}

Now I want query all the items belong to Catalog:50008064,how to? (the catalog id "50008064" , catalog name "Apple")

Remon van Vliet · Accepted Answer · 2012-04-10 09:55:20Z

3

You cannot query this in an efficient manner and performance will decrease as your data grows. As such I would consider it a schema bug and you should refactor/migrate to the following model which does allow for indexing :

{"ProductName":"XXXX",
   "Catalogs" : [
    {
        id : "50008064",
        value : "Apple"
    },
    {
        id : "50010566",
        value : "Box"
    },
    {
        id : "50016422",
        value : "Water"
    }
]}

And then index :

ensureIndex({'Catalogs.id':1})

Again, I strongly suggest you change your schema as this is a potential performance bottleneck you cannot fix any other way.

answered Apr 10, 2012 at 9:55

Remon van Vliet

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2 Comments

ericyue Over a year ago

then how to query the catalogs ? like this ?db.products.find({ "Catalogs.50008064" : { $exists: true } } )

Remon van Vliet Over a year ago

No, like db.products.find({'Catalogs.id':50008064}) which is a lot cleaner and faster.

kufi · Accepted Answer · 2012-04-10 07:20:13Z

0

This should probably work according to the entry here, although this won't be very fast, as stated in in the link.

db.products.find({ "Catalogs.50008064" : { $exists: true } } )

answered Apr 10, 2012 at 7:20

kufi

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