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From "Sylvain Lebresne (Created) (JIRA)" <j...@apache.org>
Subject [jira] [Created] (CASSANDRA-3798) get_count paging often asks for a page uselessly
Date Fri, 27 Jan 2012 14:36:15 GMT
get_count paging often asks for a page uselessly
------------------------------------------------

                 Key: CASSANDRA-3798
                 URL: https://issues.apache.org/jira/browse/CASSANDRA-3798
             Project: Cassandra
          Issue Type: Improvement
    Affects Versions: 1.0.0
            Reporter: Sylvain Lebresne
            Assignee: Sylvain Lebresne
            Priority: Minor
             Fix For: 1.1


Current get_count paging stopping condition is:
{noformat}
if ((requestedCount == 0) || ((columns.size() == 1) && (lastName.equals(predicate.slice_range.start))))
{
    break;
}
{noformat}
On a "count how many columns this row has" query (arguably the main reason why you'd use get_count),
requestedCount will never be 0, and so we'll stop whenever a page has only returned the last
column of the preceding page. While this isn't wrong, we could stop as soon as a page returns
less element than requested and avoid querying that last 1 column page.

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