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From "Brandon Williams (JIRA)" <j...@apache.org>
Subject [jira] [Created] (CASSANDRA-3224) LeveledCompactionStrategy is too complacent
Date Sat, 17 Sep 2011 18:11:11 GMT
LeveledCompactionStrategy is too complacent
-------------------------------------------

                 Key: CASSANDRA-3224
                 URL: https://issues.apache.org/jira/browse/CASSANDRA-3224
             Project: Cassandra
          Issue Type: Bug
          Components: Core
    Affects Versions: 1.0.0
            Reporter: Brandon Williams
            Assignee: Benjamin Coverston
             Fix For: 1.0.0


As the title, it barely does anything.  I inserted 50G worth of data with 1G heap and 99%
overwrite ratio, and it only compacted twice:

{noformat}
 INFO [CompactionExecutor:1] 2011-09-16 22:29:58,606 CompactionTask.java (line 220) Compacted
to [/var/lib/cassandra/data/Keyspace1/Standard1-h-2-Data.db,/var/lib/cassandra/data/Keyspace1/Standard1-h-4-Data.db,/var/lib/cassandra/data/Keyspace1/Standard1-h-5-Data.db,].
 12,595,811 to 12,595,811 (~100% of original) bytes for 40,501 keys at 3.058122MBPS.  Time:
3,928ms.
 INFO [CompactionExecutor:1] 2011-09-16 22:29:58,607 CompactionTask.java (line 222) CF Total
Bytes Compacted: 12,595,811
 INFO [CompactionExecutor:3] 2011-09-16 22:29:58,889 CompactionTask.java (line 118) Compacting
[SSTableReader(path='/var/lib/cassandra/data/Keyspace1/Standard1-h-4-Data.db'), SSTableReader(path='/var/lib/cassandra/data/Keyspace1/Standard1-h-2-Data.db'),
SSTableReader(path='/var/lib/cassandra/data/Keyspace1/Standard1-h-5-Data.db'), SSTableReader(path='/var/lib/cassandra/data/Keyspace1/Standard1-h-3-Data.db')]
 INFO [CompactionExecutor:3] 2011-09-16 22:30:06,900 CompactionTask.java (line 220) Compacted
to [/var/lib/cassandra/data/Keyspace1/Standard1-h-7-Data.db,/var/lib/cassandra/data/Keyspace1/Standard1-h-9-Data.db,/var/lib/cassandra/data/Keyspace1/Standard1-h-11-Data.db,/var/lib/cassandra/data/Keyspace1/Standard1-h-12-Data.db,/var/lib/cassandra/data/Keyspace1/Standard1-h-14-Data.db,/var/lib/cassandra/data/Keyspace1/Standard1-h-15-Data.db,].
 28,374,396 to 28,374,396 (~100% of original) bytes for 91,236 keys at 3.380379MBPS.  Time:
8,005ms.
 INFO [CompactionExecutor:3] 2011-09-16 22:30:06,901 CompactionTask.java (line 222) CF Total
Bytes Compacted: 40,970,207
{noformat}

Resulting in the following levels:

{noformat}
L0: 4965
L1: 6
L2: 0
L3: 0
L4: 0
L5: 0
L6: 0
L7: 0
{noformat}

This is obviously going to result in extremely poor read performance.

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