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Posted to commits@cassandra.apache.org by "Josh McKenzie (Jira)" <ji...@apache.org> on 2020/04/18 19:58:00 UTC

[jira] [Updated] (CASSANDRA-11223) Queries with LIMIT filtering on clustering columns can return less rows than expected

     [ https://issues.apache.org/jira/browse/CASSANDRA-11223?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Josh McKenzie updated CASSANDRA-11223:
--------------------------------------
    Bug Category: Parent values: Correctness(12982)Level 1 values: API / Semantic Implementation(12988)

> Queries with LIMIT filtering on clustering columns can return less rows than expected
> -------------------------------------------------------------------------------------
>
>                 Key: CASSANDRA-11223
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-11223
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Legacy/Local Write-Read Paths
>            Reporter: Benjamin Lerer
>            Assignee: Benjamin Lerer
>            Priority: Normal
>             Fix For: 2.2.11, 3.0.15, 3.11.1, 4.0
>
>
> 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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