mongodb geoNear vs near

Question

It looks like mongodb offers two similar functions for geospatial queries - $near and $geoNear. According to the mongo docs

The geoNear command provides an alternative to the $near operator. In addition to the functionality of $near, geoNear returns additional diagnostic information.

It looks like geoNear provides a superset of the near functionality. For example, near seems to only return the closest 100 documents, whereas geoNear lets you specify a maximum. Is there a reason to use near instead of geoNear? Is one more efficient than the other?

Answer 1

Efficiency should be identical for either.

geoNear's major limitation is that as a command it can return a result set up to the maximum document size as all of the matched documents are returned in a single result document. It also requires that a distance field be added to each result document which may or may not be an issue depending on your usage.

$near is a query operator so the results can be larger than a single document (they are still returned in a single response but not a single document). You can also set the maximum number of documents via the query's limit().

I tend to recommend that users stick with the $near unless they need the diagnostics (e.g., distance, or location matched) from the geonear command.

Answer 2

These are major differences :-

1. $geoNear also gives you distance from the point but $near command doesn't.

2. $geoNear command requires that the collection have at most only one 2d index and/or only one 2dsphere index whereas geospatial query operators like $near and $geoWithin permit collections to have multiple geospatial indexes. This is because in $geoNear command there is no option to specify the field on which you want to search, where as in $near command you can specify the field name.

Answer 3

The main difference is that $near is a query operator, but $geoNear is an aggregation stage. Both return documents in order of nearest to farthest from the given point.

What it means is that $near can be used in find() queries or in the $match aggregation stage, but $geoNear cannot. Instead $geoNear must be used as a separate aggregation stage only.

The options each feature provides also differ. I invite you to review the details in the corresponding documentation sections:

$near documentation
$geoNear documentation