By default, queries in MongoDB return all fields in matching documents. To limit the amount of data that MongoDB sends to applications, you can include a ... ... <看更多>
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By default, queries in MongoDB return all fields in matching documents. To limit the amount of data that MongoDB sends to applications, you can include a ... ... <看更多>
The document is compressed on storage , so mongo need to read the document first , uncompress it and get the fields specified in the filter ... ... <看更多>
但很多時候我們沒有想要知道所有field-value 資料,只想去檢視特定的field-value 資料,這時候就需要用到MongoDB 的映射Projection觀念,也就是只選擇document 中的 ... ... <看更多>
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When using projection to remove unused fields, the MongoDB server will have to fetch each full document into memory (if it isn't already there) ... ... <看更多>
Selecting MongoDB Fields Using Projection Queries. mongodb, mongo, whitelisting, blacklisting, field selection, column selection. ... <看更多>