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https://issues.apache.org/jira/browse/CASSANDRA-4579?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13442709#comment-13442709
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paul cannon commented on CASSANDRA-4579:
----------------------------------------
Thanks to Christoph Hack for identifying the problem.
> CQL queries using LIMIT sometimes missing results
> -------------------------------------------------
>
> Key: CASSANDRA-4579
> URL: https://issues.apache.org/jira/browse/CASSANDRA-4579
> Project: Cassandra
> Issue Type: Bug
> Components: Core
> Affects Versions: 1.2.0
> Reporter: paul cannon
> Labels: cql, cql3
> Fix For: 1.2.0
>
>
> In certain conditions, CQL queries using LIMIT clauses are not being given
> all of the expected results (whether unset column values or missing rows).
> Here are the condition sets I've been able to identify:
> First mode: all rows are returned, but in the last row of results, all
> columns which are not part of the primary key receive no values, except for
> the first non-primary-key column. Conditions:
> * Table has a multi-component primary key
> * Table has more than one column which is not a component of the primary key
> * The number of results which would be returned by a query is equal to or
> more than the specified LIMIT
> Second mode: result has fewer rows than it should, lower than both the LIMIT
> and the actual number of matching rows. Conditions:
> * Table has a single-column primary key
> * Table has more than one column which is not a component of the primary key
> * The number of results which would be returned by a query is equal to or
> more than the specified LIMIT
> It would make sense to me that this would have started with CASSANDRA-4329,
> but bisecting indicates that this behavior started with commit
> 91bdf7fb4220b27e9566c6673bf5dbd14153017c, implementing CASSANDRA-3647.
> Test case for the first failure mode:
> {noformat}
> DROP KEYSPACE test;
> CREATE KEYSPACE test
> WITH strategy_class = 'SimpleStrategy'
> AND strategy_options:replication_factor = 1;
> USE test;
> CREATE TABLE testcf (
> a int,
> b int,
> c int,
> d int,
> e int,
> PRIMARY KEY (a, b)
> );
> INSERT INTO testcf (a, b, c, d, e) VALUES (1, 11, 111, 1111, 11111);
> INSERT INTO testcf (a, b, c, d, e) VALUES (2, 22, 222, 2222, 22222);
> INSERT INTO testcf (a, b, c, d, e) VALUES (3, 33, 333, 3333, 33333);
> INSERT INTO testcf (a, b, c, d, e) VALUES (4, 44, 444, 4444, 44444);
> SELECT * FROM testcf;
> SELECT * FROM testcf LIMIT 1; -- columns d and e in result row are null
> SELECT * FROM testcf LIMIT 2; -- columns d and e in last result row are null
> SELECT * FROM testcf LIMIT 3; -- columns d and e in last result row are null
> SELECT * FROM testcf LIMIT 4; -- columns d and e in last result row are null
> SELECT * FROM testcf LIMIT 5; -- results are correct (4 rows returned)
> {noformat}
> Test case for the second failure mode:
> {noformat}
> CREATE KEYSPACE test
> WITH strategy_class = 'SimpleStrategy'
> AND strategy_options:replication_factor = 1;
> USE test;
> CREATE TABLE testcf (
> a int primary key,
> b int,
> c int,
> );
> INSERT INTO testcf (a, b, c) VALUES (1, 11, 111);
> INSERT INTO testcf (a, b, c) VALUES (2, 22, 222);
> INSERT INTO testcf (a, b, c) VALUES (3, 33, 333);
> INSERT INTO testcf (a, b, c) VALUES (4, 44, 444);
> SELECT * FROM testcf;
> SELECT * FROM testcf LIMIT 1; -- gives 1 row
> SELECT * FROM testcf LIMIT 2; -- gives 1 row
> SELECT * FROM testcf LIMIT 3; -- gives 2 rows
> SELECT * FROM testcf LIMIT 4; -- gives 2 rows
> SELECT * FROM testcf LIMIT 5; -- gives 3 rows
> {noformat}
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