mongodb，集合数据结构对性能的影响

Question

on the define the collection data structure, how to judge which structure is a good design or decision? This will affect the subsequent access to the database performance.

for example:

when the one data like this:

{
    _id:'a'
    index:1,   //index 1~n
    name:'john'
}

When n is large, meaning that data will be large and frequent deposited.

the collection data structure will be to one dimensional object :

{
    _id:'a'
    index:1,   
    name:'john'
}
.
.
.
{
    _id:'a'
    index:99,   
    name:'jule'
}

Or a composite two-dimensional object :

{
    _id:'a'
    info:[
        {index:1,name:'john'},...,{index:99,name:'jule'}   
    ]
}

composite two-dimensional object can effectively reduce the number of data, however, the search method is not convenient for writing, and whether it will actually reduce the effectiveness of searching or depositing a database.

Or the number of data is the key to affecting the effectiveness of the database.

Answer 1

"Better" means different things to different use cases. What works in your case might not necessarily work in other use cases.

Generally, it is better to avoid large arrays, due to:

1. MongoDB's document size limitation (16MB).
2. Indexing a large array is typically not very performant.

However, this is just a general observation and not a specific rule of thumb. If your data lends itself to an array-based representation and you're certain you'll never hit the 16MB document size, then that design may be the way to go (again, specific to your use case).

You may find these links useful to get started in schema design:

• 6 Rules of Thumb for MongoDB Schema Design: Part 1
• Part 2
• Part 3
• Data Models
• Use Cases
• Query Optimization
• Explain Results