[jira] [Created] (CASSANDRA-8859) CollationController not using collectTimeOrderedData

["Michael Mior (JIRA)" <ji...@apache.org>]

Michael Mior created CASSANDRA-8859:
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             Summary: CollationController not using collectTimeOrderedData
                 Key: CASSANDRA-8859
                 URL: https://issues.apache.org/jira/browse/CASSANDRA-8859
             Project: Cassandra
          Issue Type: Bug
          Components: Core
            Reporter: Michael Mior
            Priority: Minor


I'd appreciate some help with a Cassandra 2.1.2 issue I'm experiencing. I'm running a query which looks like this:

{code}
CREATE TABLE single_row_fetch (id uuid PRIMARY KEY, data text)
SELECT data FROM single_row_fetch WHERE id = ?
{code}

When writing test data into this table, I disabled compaction. I then wrote data for performed a flush, and then overwrote the data, and so on. I varied the number of times the data was overwritten and flushed. This has the effect of controlling the number of SSTables. However, given that the table only has one non-key row, only a single SSTable will ever have the most recent data for this row. I confirmed that the expected number of SSTables were generated and the timestamps of the  are as expected.

However, when I run the query with tracing, I see that Cassandra still reads from ALL of the SSTables via {{collectAllData}} in {{CollationController}}. Given that this query only fetches a single column, I would expect this query to take the {{collectTimeOrderedData}} code path and then only examine the first SSTable after seeing that it contains the relevant data.

Any insights on why this is the case and it what situations I would get the expected behaviour would be incredibly helpful!



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