mongodb - What is the performance implications of nested hashes in mongodb?

Question

So I have a very large set of metrics (15GB and growing) that has some of the data in nested hashes. Like so:

{
   _id: 'abc0000',
   type: 'foo',
   data: { a: 20, b: 30, c: 3 }
},
... more data following this schema...
{
   _id: 'abc5000',
   type: 'bar'
   data: { a: 1,  b: 2,  c: 4, d: 10 }
}

What is the performance implications when I run a query on the nested hashes? The data inside the hash can't be indexed...or rather, it would be pointless to index it.

I can always reform the data into a flat style data_a, data_b, etc...

Answer 1

您可以在嵌套散列中的属性上创建索引。查看Indexing with dot notation了解更多详细信息。如果需要，您还可以创建复合索引，但要注意并行数组的注意事项。基本上，如果您创建一个复合索引，那么只有一个索引值可以是数组，但是，这不应该影响您（从发布的架构来看）。

data.a因此，您可以在上data.b或data.a, data.c根据您的需要创建索引。