Database Management Systems
In MongoDB, you can use the cursor.explain() method or the db.collection.explain() method to determine whether or not a query uses an index.
These methods enable you to view the query plan for the query, which includes whether or not it uses an index.
In MongoDB, the $sample aggregation pipeline stage randomly selects the specified number of documents from its input.
In MongoDB, the $rand aggregation pipeline operator returns a random float between 0 and 1.
The floating point value has up to 17 digits after the decimal point. Any trailing zeros are dropped, so the number of digits may vary.
The $rand operator was introduced in MongoDB 4.4.2.
If you encounter error Msg 15123, Level 16, reading “The configuration option ‘Agent XPs’ does not exist“, you were probably trying to execute EXEC SP_CONFIGURE 'Agent XPs' while advanced options are hidden.
This error is easily fixed.
In MongoDB, the $nin query operator selects the documents where the field’s value is not in the specified array or where the field doesn’t exist.
In MongoDB, the $ne aggregation pipeline operator compares two values and returns either true or false, depending on whether the two values are not equivalent.
In MongoDB, the $in aggregation pipeline operator returns a boolean indicating whether a specified value is in the array.
The $in aggregation pipeline operator is not to be confused with the $in query operator, which selects the documents where the value of a field equals any value in the specified array.
In MongoDB, the $in query operator selects the documents where the value of a field equals any value in the specified array.
The $in query operator is not to be confused with the $in aggregation pipeline operator, which returns a boolean indicating whether a specified value is in the array.
If you no longer need a database in MongoDB you can delete it.
Technically speaking, the term normally used for deleting a database is drop. To drop a database is to delete it.
In any case, below are two ways you can drop/delete a database in the mongo shell.
In MongoDB, the $gte aggregation pipeline operator compares two values and returns either true or false, depending on whether or not the first value is greater than or equal to the second value.