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From Mike Smith <m...@mailchannels.com>
Subject Problem SliceByNamesReadCommand on super column family after flush operation
Date Wed, 02 Nov 2011 00:06:36 GMT
Hi,

I'm having a problem with doing a multiget_slice on a super column family
after its first flush. Updates to the column values work properly, but
trying to retrieve the updated values using a multiget_slice operation fail
to get the updated values. Instead they return the values from before the
flush. I've seen this problem in Cassandra v1.0.0 and v1.0.1. The problem
is not present in Cassandra v0.7.6.

Steps to reproduce:

   1. Create one or more super column entries
   2. Verify the sub column values can be updated and that you can retrieve
   the new values
   3. Use nodetool to flush the column family or restart cassandra
   4. Update the sub column values
   5. Verify they have been updated using cassandra-cli
   6. Verify you *DO NOT* get the updated values when doing a
   multiget_slice; instead you get the old values from before the flush

You can get the most recent value by doing a flush followed by a major
compaction. However, future updates are not retrieved properly either.

With debug turned on, it looks like the multiget_slice query uses the
following command/consistency level:
SliceByNamesReadCommand(table='test_cassandra', key=666f6f,
columnParent='QueryPath(columnFamilyName='test', superColumnName='null',
columnName='null')', columns=[foo,])/QUORUM.

Cassandra-cli uses the following command/consistency level for a get_slice:
SliceFromReadCommand(table='test_cassandra', key='666f6f',
column_parent='QueryPath(columnFamilyName='test', superColumnName='null',
columnName='null')', start='', finish='', reversed=false,
count=1000000)/QUORUM

Notice the test program gets 'bar2' for the column values and cassandra-cli
gets 'bar3' for the column values:

tcpdump from test program using hector-core:1.0-1

16:46:07.424562 IP iam.47158 > iam.9160: Flags [P.], seq 55:138, ack 30,
win 257, options [nop,nop,TS val 27474096 ecr 27474095], length 83
E....#@.@.PK.........6#.....].8......{.....
..8...8.........multiget_slice................foo..........test................foo.........
16:46:07.424575 IP iam.9160 > iam.47158: Flags [.], ack 138, win 256,
options [nop,nop,TS val 27474096 ecr 27474096], length 0
E..4..@.@.<.........#..6].8..........(.....
..8...8.
16:46:07.428771 IP iam.9160 > iam.47158: Flags [P.], seq 30:173, ack 138,
win 256, options [nop,nop,TS val 27474097 ecr 27474096], length 143
@.@.<&........#..6].8................
............foo...............foo...............foo1.......bar2
........6h........foo2.......bar2
........I.....


tcpdump of cassandra-cli:

16:30:55.945123 IP iam.47134 > iam.9160: Flags [P.], seq 370:479, ack 5310,
win 387, options [nop,nop,TS val 27246226 ecr 27241207], length 109
E.....@.@.9q..........#..n.X\
.............
................get_range_slices..............test.........................................................d.........
16:30:55.945152 IP iam.9160 > iam.47134: Flags [.], ack 479, win 256,
options [nop,nop,TS val 27246226 ecr 27246226], length 0
E..4..@.@.".........#...\
...n.......(.....
........
16:30:55.949245 IP iam.9160 > iam.47134: Flags [P.], seq 5310:5461, ack
479, win 256, options [nop,nop,TS val 27246227 ecr 27246226], length 151
E.....@.@."V........#...\
...n.............
....................get_range_slices...................foo..................foo...............foo1.......bar3
........&.........foo2.......bar3
........: .....

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