Details
Normal Description
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):
ResultSet result = session.execute("SELECT key, col1, col2, col3 FROM mytable"); for (Row row : result) { // do some work with row }
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):
AbstractQueryPager.fetchPage(int): * pageSize=5000, currentPageSize=5001, rows size=5002, liveCount=5001 * containsPreviousLast(rows.get(0)) returns true -> AbstractQueryPager.discardFirst(List<Row>): * 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(List<Row>): * discarded = 0; * count = newCf.getColumnCount() = 0;
-> assert discarded == 1 throws AssertionError