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Posted to commits@cassandra.apache.org by "Benjamin Lerer (JIRA)" <ji...@apache.org> on 2016/02/24 15:50:18 UTC
[jira] [Created] (CASSANDRA-11223) Queries with LIMIT filtering on
clustering columns can return less row than expected
Benjamin Lerer created CASSANDRA-11223:
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Summary: Queries with LIMIT filtering on clustering columns can return less row than expected
Key: CASSANDRA-11223
URL: https://issues.apache.org/jira/browse/CASSANDRA-11223
Project: Cassandra
Issue Type: Bug
Components: Local Write-Read Paths
Reporter: Benjamin Lerer
Assignee: Benjamin Lerer
A query like {{SELECT * FROM %s WHERE b = 1 LIMIT 2 ALLOW FILTERING}} can return less row than expected if the table has some static columns and some of the partition have no rows matching b = 1.
The problem can be reproduced with the following unit test:
{code}
public void testFilteringOnClusteringColumnsWithLimitAndStaticColumns() throws Throwable
{
createTable("CREATE TABLE %s (a int, b int, s int static, c int, primary key (a, b))");
for (int i = 0; i < 3; i++)
{
execute("INSERT INTO %s (a, s) VALUES (?, ?)", i, i);
for (int j = 0; j < 3; j++)
if (!(i == 0 && j == 1))
execute("INSERT INTO %s (a, b, c) VALUES (?, ?, ?)", i, j, i + j);
}
assertRows(execute("SELECT * FROM %s"),
row(1, 0, 1, 1),
row(1, 1, 1, 2),
row(1, 2, 1, 3),
row(0, 0, 0, 0),
row(0, 2, 0, 2),
row(2, 0, 2, 2),
row(2, 1, 2, 3),
row(2, 2, 2, 4));
assertRows(execute("SELECT * FROM %s WHERE b = 1 ALLOW FILTERING"),
row(1, 1, 1, 2),
row(2, 1, 2, 3));
assertRows(execute("SELECT * FROM %s WHERE b = 1 LIMIT 2 ALLOW FILTERING"),
row(1, 1, 1, 2),
row(2, 1, 2, 3)); // <-------- FAIL It returns only one row because the static row of partition 0 is counted and filtered out in SELECT statement
}
{code}
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