Hey, I created a table with a wide row. Query on the wide row after removing the entries and flushing the table becomes very slow. I am aware of the impact of tombstones but it seems that there is a deadlock which prevents the query to be completed.
step by step: 1. creating the keyspace and the table: CREATE KEYSPACE test WITH replication = {'class': 'SimpleStrategy', 'replication_factor': '1'}; use test; CREATE TABLE job_index ( stage text, "timestamp" text, PRIMARY KEY (stage, "timestamp") ) WITH gc_grace_seconds=10 AND compaction={'sstable_size_in_mb': '10', 'class': 'LeveledCompactionStrategy'}; 2. insert 5000 entries to the job_index column family using the attached script (insert_1-5000.cql) 3. flushing the table: nodetool flush test job_index 4. delete the 5000 entries in the wide row using the attached script (delete_1-5000.cql) so far the queries return all the entries in the wide row in a fraction of a second. 5. flushing the table: nodetool flush test job_index 6. run the following query: cqlsh:test> SELECT * from job_index limit 1 ; Request did not complete within rpc_timeout. The execution of the query gets blocked and eventually the query times out. In the cassandra's log file I see the following lines: DEBUG [ScheduledTasks:1] 2013-07-01 19:10:39,469 GCInspector.java (line 121) GC for ParNew: 16 ms for 5 collections, 754590496 used; max is 2093809664 DEBUG [ScheduledTasks:1] 2013-07-01 19:10:40,473 GCInspector.java (line 121) GC for ParNew: 19 ms for 6 collections, 547894840 used; max is 2093809664 DEBUG [ScheduledTasks:1] 2013-07-01 19:10:41,475 GCInspector.java (line 121) GC for ParNew: 16 ms for 5 collections, 771812864 used; max is 2093809664 A few minutes later after the compaction finishes the problem goes away. I am using cassandra 1.2.6. I tested on Linux (CentOS) and MacOS and I get the same result! Is this a known issue?