search document by id very slow

[kRyszard]

Hi, my documents has an id field, called "doc_id", declared with the following attributes: <field name="doc_id" type="long" indexed="true" stored="true" required="true" />

This id is marked as an unique key with the <uniqueKey> tag.

I try to load many documents at once, giving their ids in request f.e. doc_id:(235, 163, 256, ..., 10473)

The count of identifiers in the query is never greater than 100. However, the more documents are there in the storage the longer it takes for this query to execute. I thought this would be something like the SQL query f.e. "select doc where doc_id in (...)" but with index on "doc_id" the execution time should be constant, shouldn't it? So why is it slowing down in solandra after I add more and more docs?

Regards, K