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https://issues.apache.org/jira/browse/CASSANDRA-6447?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13838841#comment-13838841
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Julien Aymé edited comment on CASSANDRA-6447 at 12/4/13 12:13 PM:
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Also, since newCf.getColumnCount() == 0, the rest of the code is still valid
(the row will not be included in the returned Rows).
Therefore, I think that the assert statement should be transformed to:
{code}
assert discarded == 1 || discarded == 0;
{code}
Or that the assert statement should be dropped, since it was introduced in the
last commit on AbstractQueryPager:
See:
https://git-wip-us.apache.org/repos/asf?p=cassandra.git;a=commit;h=3c9760bdb986f6c2430adfc13c86ecb75c3246ac
was (Author: julien.a...@gmail.com):
Also, since newCf.getColumnCount() == 0, the rest of the code is still valid
(the row will not be included in the returned Rows).
Therefore, I think that the assert statement should be transformed to:
{code}
assert discarded == 1 || discarded == 0;
{code}
Or that the assert statement should be dropped.
SELECT someColumns FROM table results in AssertionError in
AbstractQueryPager.discardFirst
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Key: CASSANDRA-6447
URL: https://issues.apache.org/jira/browse/CASSANDRA-6447
Project: Cassandra
Issue Type: Bug
Components: Core
Environment: Cluster: single node server (ubuntu)
Cassandra version: 2.0.3 (server/client)
Client: Datastax cassandra-driver-core 2.0.0-rc1
Reporter: Julien Aymé
Attachments: stacktrace.txt
I have a query which must read all the rows from the table:
Query: SELECT key, col1, col2, col3 FROM mytable
Here is the corresponding code (this is using datastax driver):
{code}
ResultSet result = session.execute(SELECT key, col1, col2, col3 FROM
mytable);
for (Row row : result) {
// do some work with row
}
{code}
Messages sent from the client to Cassandra:
* 1st: {{QUERY SELECT key, col1, col2, col3 FROM mytable([cl=ONE, vals=[],
skip=false, psize=5000, state=null, serialCl=ONE])}}
* 2nd: {{QUERY SELECT key, col1, col2, col3 FROM mytable([cl=ONE, vals=[],
skip=false, psize=5000, state=java.nio.HeapByteBuffer[pos=24 lim=80
cap=410474], serialCl=ONE])}}
On the first message, everything is fine, and the server returns 5000 rows.
On the second message, paging is in progress, and the server fails in
AbstractQueryPager.discardFirst: AssertionError (stack trace attached).
Here is some more info (step by step debugging on reception of 2nd message):
{code}
AbstractQueryPager.fetchPage(int):
* pageSize=5000, currentPageSize=5001, rows size=5002, liveCount=5001
* containsPreviousLast(rows.get(0)) returns true
- AbstractQueryPager.discardFirst(ListRow):
* rows size=5002
* first=TreeMapBackedSortedColumns[with TreeMap size=1]
- AbstractQueryPager.discardHead(ColumnFamily, ...):
* counter = ColumnCounter$GroupByPrefix
* iter.hasNext() returns true (TreeMap$ValueIterator with TreeMap size=1)
* Column c = DeletedColumn
* counter.count() - c.isLive returns false (c is DeletedColumn)
* counter.live() = 0
* iter.hasNext() returns false
* Math.min(0, toDiscard==1) returns 0
- AbstractQueryPager.discardFirst(ListRow):
* discarded = 0;
* count = newCf.getColumnCount() = 0;
{code}
- assert discarded == 1 *throws AssertionError*
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