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Posted to commits@cassandra.apache.org by "John Chakerian (Created) (JIRA)" <ji...@apache.org> on 2012/01/18 06:10:39 UTC
[jira] [Created] (CASSANDRA-3750) Migrations and Schema CFs use
disk space proportional to the square of the number of CFs
Migrations and Schema CFs use disk space proportional to the square of the number of CFs
----------------------------------------------------------------------------------------
Key: CASSANDRA-3750
URL: https://issues.apache.org/jira/browse/CASSANDRA-3750
Project: Cassandra
Issue Type: Bug
Components: Core
Affects Versions: 1.0.1
Environment: Linux (CentOS 5.7)
Reporter: John Chakerian
Attachments: fit.png
The system keyspace grows proportional to the square of the number of CFs (more likely, it grows quadratically with # of schema changes in general). The major offenders in the keyspace are the Migrations table & the Schema table. On clusters with very large #s of CFs (in the low thousands), we think that these large system tables may be contributing to various performance issues.
The approximate expression is: s = 0.0003253*n^2 + 2.58, where n is # of keyspaces + # of schemas and s is the size of the system keyspace in megabytes. See attached plot of the regression curve showing fit.
Sampled data:
{noformat}
NUM_CFS SYSTEM_SIZE_IN_MB
100 4.4
200 15
300 32
400 55
500 85
600 120
700 162
800 211
900 266
1000 327
{noformat}
This was hit in 1.0.1, but is almost certainly not version specific.
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[jira] [Resolved] (CASSANDRA-3750) Migrations and Schema CFs use
disk space proportional to the square of the number of CFs
Posted by "Sylvain Lebresne (Resolved) (JIRA)" <ji...@apache.org>.
[ https://issues.apache.org/jira/browse/CASSANDRA-3750?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Sylvain Lebresne resolved CASSANDRA-3750.
-----------------------------------------
Resolution: Duplicate
While it is not yet committed, CASSANDRA-1391 will almost surely fix that, so marking that one as duplicate.
> Migrations and Schema CFs use disk space proportional to the square of the number of CFs
> ----------------------------------------------------------------------------------------
>
> Key: CASSANDRA-3750
> URL: https://issues.apache.org/jira/browse/CASSANDRA-3750
> Project: Cassandra
> Issue Type: Bug
> Components: Core
> Affects Versions: 1.0.1
> Environment: Linux (CentOS 5.7)
> Reporter: John Chakerian
> Attachments: fit.png
>
>
> The system keyspace grows proportional to the square of the number of CFs (more likely, it grows quadratically with # of schema changes in general). The major offenders in the keyspace are the Migrations table & the Schema table. On clusters with very large #s of CFs (in the low thousands), we think that these large system tables may be contributing to various performance issues.
> The approximate expression is: s = 0.0003253*n^2 + 2.58, where n is # of keyspaces + # of schemas and s is the size of the system keyspace in megabytes. See attached plot of the regression curve showing fit.
> Sampled data:
> {noformat}
> NUM_CFS SYSTEM_SIZE_IN_MB
> 100 4.4
> 200 15
> 300 32
> 400 55
> 500 85
> 600 120
> 700 162
> 800 211
> 900 266
> 1000 327
> {noformat}
> This was hit in 1.0.1, but is almost certainly not version specific.
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If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa
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[jira] [Updated] (CASSANDRA-3750) Migrations and Schema CFs use
disk space proportional to the square of the number of CFs
Posted by "John Chakerian (Updated) (JIRA)" <ji...@apache.org>.
[ https://issues.apache.org/jira/browse/CASSANDRA-3750?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
John Chakerian updated CASSANDRA-3750:
--------------------------------------
Attachment: fit.png
> Migrations and Schema CFs use disk space proportional to the square of the number of CFs
> ----------------------------------------------------------------------------------------
>
> Key: CASSANDRA-3750
> URL: https://issues.apache.org/jira/browse/CASSANDRA-3750
> Project: Cassandra
> Issue Type: Bug
> Components: Core
> Affects Versions: 1.0.1
> Environment: Linux (CentOS 5.7)
> Reporter: John Chakerian
> Attachments: fit.png
>
>
> The system keyspace grows proportional to the square of the number of CFs (more likely, it grows quadratically with # of schema changes in general). The major offenders in the keyspace are the Migrations table & the Schema table. On clusters with very large #s of CFs (in the low thousands), we think that these large system tables may be contributing to various performance issues.
> The approximate expression is: s = 0.0003253*n^2 + 2.58, where n is # of keyspaces + # of schemas and s is the size of the system keyspace in megabytes. See attached plot of the regression curve showing fit.
> Sampled data:
> {noformat}
> NUM_CFS SYSTEM_SIZE_IN_MB
> 100 4.4
> 200 15
> 300 32
> 400 55
> 500 85
> 600 120
> 700 162
> 800 211
> 900 266
> 1000 327
> {noformat}
> This was hit in 1.0.1, but is almost certainly not version specific.
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If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa
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