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From "Robert Newson (JIRA)" <j...@apache.org>
Subject [jira] Updated: (COUCHDB-220) Extreme sparseness in couch files
Date Sun, 05 Apr 2009 23:25:12 GMT

     [ https://issues.apache.org/jira/browse/COUCHDB-220?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Robert Newson updated COUCHDB-220:
----------------------------------

    Attachment: attachment_sparseness.js
                220.patch


Don't force 64k inflation, test to demonstrate lack of sparseness.

> Extreme sparseness in couch files
> ---------------------------------
>
>                 Key: COUCHDB-220
>                 URL: https://issues.apache.org/jira/browse/COUCHDB-220
>             Project: CouchDB
>          Issue Type: Bug
>          Components: Database Core
>    Affects Versions: 0.9
>         Environment: ubuntu 8.10 64-bit, ext3
>            Reporter: Robert Newson
>         Attachments: 220.patch, attachment_sparseness.js
>
>
> When adding ten thousand documents, each with a small attachment, the discrepancy between
reported file size and actual file size becomes huge;
> ls -lh shard0.couch
> 698M 2009-01-23 13:42 shard0.couch
> du -sh shard0.couch
> 57M	shard0.couch
> On filesystems that do not support write holes, this will cause an order of magnitude
more I/O.
> I think it was introduced by the streaming attachment patch as each attachment is followed
by huge swathes of zeroes when viewed with 'hd -v'.
> Compacting this database reduced it to 7.8mb, indicating other sparseness besides attachments.

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