[jira] Commented: (COUCHDB-220) Extreme sparseness in couch files

["Robert Newson (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/COUCHDB-220?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12666548#action_12666548 ] 

Robert Newson commented on COUCHDB-220:
---------------------------------------

According to Wikipedia (http://en.wikipedia.org/wiki/Sparse_file) HFS+ does not support sparse files.

> 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
>
> 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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