Haystack and Elasticsearch: Limit number of results

Question

I have 2 servers with Haystack:

• Server1: This has elasticsearch installed
• Server2: This doesn't have elasticsearch, the queries are made to Server1

My issue is about pagination when I make queries from Server2 to Server1:

• Server2 makes query to Server1
• Server1 send all the results back to Server2
• Server2 makes the pagination

But this is not optimal, if the query return 10.000 objects, the query will be slow.

I know that you can send to elasticsearch some values in the query (size, from and to) but I don't know if this is possible using Haystack, I've checked documentation and googled it and found nothing.

• How could I configure the query in Haystack to receive the results 10 by 10 ?

Edit

• Is possible that if I make SearchQuerySet()[10000:10010] it will only ask for this 10 items ?
• Or it will ask for all the items and then filter them ?

Edit2

I found this on Haystack Docs:

• SearchQuery API - set_limits

it seems a function to do whatt I'm trying to do:

Restricts the query by altering either the start, end or both offsets.

And then I tried to do:

from haystack.query import SearchQuerySet

sqs = SearchQuerySet()
sqs.query.set_limits(low=0, high=4)
sqs.filter(content='anything')

The result is the full list, like I never add the set_limit line

• Why is not working ?

Answer 1

Haystack works kinda different from Django ORM. After limiting the queryset, you should call get_results() in order to get limited results. This is actually smart, because it avoids multiple requests from Elastic.

Example:

# Assume you have 800 records.
sqs = SearchQuerySet()
sqs.query.set_limits(low=0, high=4)
len(sqs)  # Will return 800 records
len(sqs.get_results())  # Will return first 4 records.

Hope that it helps.