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From "Jonathan Ellis (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (CASSANDRA-3224) LeveledCompactionStrategy is too complacent
Date Mon, 19 Sep 2011 18:03:09 GMT

     [ https://issues.apache.org/jira/browse/CASSANDRA-3224?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Jonathan Ellis updated CASSANDRA-3224:
--------------------------------------

    Attachment: 3224-v2.txt

v2 attached w/ one-line fix to score computation

> 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: Jonathan Ellis
>              Labels: compaction
>             Fix For: 1.0.0
>
>         Attachments: 3224-v2.txt, 3224.txt
>
>
> As the title says, 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 22:29:54,572 CompactionTask.java (line 118) Compacting
[SSTableReader(path='/var/lib/cassandra/data/Keyspace1/Standard1-h-1-Data.db')]
>  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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