| layout | api-command | ||||||
|---|---|---|---|---|---|---|---|
| language | JavaScript | ||||||
| permalink | api/javascript/distinct/ | ||||||
| command | distinct | ||||||
| io |
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| related_commands |
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{% apibody %} sequence.distinct() → array table.distinct([{index: }]) → stream r.distinct(sequence) → array r.distinct(table, [{index: }]) → stream {% endapibody %}
Removes duplicates from elements in a sequence.
The distinct command can be called on any sequence or table with an index.
{% infobox %}
While distinct can be called on a table without an index, the only effect will be to convert the table into a stream; the content of the stream will not be affected.
{% endinfobox %}
Example: Which unique villains have been vanquished by Marvel heroes?
r.table('marvel').concatMap(function(hero) {
return hero('villainList')
}).distinct().run(conn, callback)Example: Topics in a table of messages have a secondary index on them, and more than one message can have the same topic. What are the unique topics in the table?
r.table('messages').distinct({index: 'topics'}).run(conn, callback)The above structure is functionally identical to:
r.table('messages')('topics').distinct().run(conn, callback)However, the first form (passing the index as an argument to distinct) is faster, and won't run into array limit issues since it's returning a stream.
