The total number of records for MongoDB querying for non-repeating data

Introductory Remarks: db.keyword.distinct ("keyword"). length

As follows:

Db.keyword.distinct ("keyword"). length

View the total number of records in the keyword field in the keyword table without duplicates

This method is not seen in the official documentation, try to find the original can be used in that way

Db.keyword.find (). Length () ==db.keyword.find (). Count ()

Of course, the length here must be in parentheses.

However, this method is only suitable for a small amount of data, test 200,000 can be, more than 1 million of the time is not, the report data is too large, we can see how much data he is likely to support according to the actual situation.

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