what is – Page 142

MongoDB $min

January 17, 2021 by Ian

MongoDB has a $min operator that allows you to update the value of a field only if the specified value is less than the current value of the field.

In other words, if the $min value is less than the current value in the document, the $min value is used. Otherwise, the document’s value remains unchanged.

MongoDB $pop

January 16, 2021 by Ian

In MongoDB, you can use the $pop operator to remove the first or last element from an array.

Use $pop in conjunction with a method such as update() to update the specified document with the change.

Use -1 to remove the first element, and 1 to remove the last.

MongoDB $pullAll

January 16, 2021 by Ian

In MongoDB, you can use the $pullAll operator to remove all instances of the specified values from an existing array.

Use $pullAll in conjunction with a method such as update(), updateOne(), or updateMany() to update the specified document/s with the change.

MongoDB $pull

January 15, 2021 by Ian

In MongoDB, you can use the $pull operator to remove values from an array.

Use $pull in conjunction with a method such as update() to update the specified document with the change.

MongoDB $addToSet

January 14, 2021 by Ian

In MongoDB, the $addToSet operator adds a value to an array unless the value is already present in the array.

It’s similar to the $push operator, except that $push adds the value even if the value is already present.

MongoDB $push

January 14, 2021 by Ian

In MongoDB, you can use the $push operator to append a value to an array.

You can use various modifiers to specify the value’s position in the array, the order of the elements in the array, append multiple values, etc.

$unionWith – MongoDB’s Equivalent of UNION ALL

January 13, 2021 by Ian

If you’re familiar with SQL, you might know about the UNION clause, which concatenates the results of two queries into a single result set. In particular, UNION ALL includes duplicates.

In MongoDB, we can use the $unionWith aggregation pipeline stage to achieve the same effect that UNION ALL produces. The $unionWith stage performs a union of two collections – it combines pipeline results from two collections into a single result set. And it includes duplicates.

MongoDB dropIndexes Command

August 5, 2024January 8, 2021 by Ian

MongoDB has an administration command called dropIndexes that drops one or more indexes (except the index on the _id field) from the specified collection.

MongoDB dropIndexes()

August 5, 2024January 8, 2021 by Ian

In MongoDB, the dropIndexes() method allows you to drop one or more indexes from a collection.

To drop a single index, pass the name of the index or its definition/specification document. If it’s a text index, you can only specify the index name.

To drop multiple indexes, pass the index names in an array.

To drop all indexes (except for the _id index), don’t pass any arguments.

MongoDB dropIndex()

August 5, 2024January 8, 2021 by Ian

There are several ways to drop an index in MongoDB, one of which is to use the dropIndex() method.

It’s pretty simple to use – just pass the name of the index or its definition/specification document. If it’s a text index, you can only specify the index name.