CODEWITHSUNDEEP
mongodb
Real Dreams
Real Dreams

Reputation: 18010

Getting next and previous document

In a mongo collection I have a list of words (millions words).

{word:'a'}
{word:'b'}
{word:'x'}
{word:'y'}
{word:'z'}

I need to get lexical adjacents of a word (next and previous). I am looking for most efficient method.

Upvotes: 1

Views: 172

Answers (1)

alexcasalboni
alexcasalboni

Reputation: 1724

Why don't you simply execute two queries?

The first one would look for documents with 'word > "YOURWORD"', sorting by 'word' (asc) with limit 1, then the second one would look for documents with 'word < "YOUTWORD"', sorting by 'word' (desc), again with limit 1.

I guess you've an index on the field, so it should be quite performant.

Here's a code example:

var prev = db.words.find({"word": {$gt: "YOURWORD"}}).sort({"word": 1}).limit(1);
var next = db.words.find({"word": {$lt: "YOURWORD"}}).sort({"word": -1}).limit(1);

Upvotes: 2

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