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https://issues.apache.org/jira/browse/COUCHDB-220?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12695940#action_12695940
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Paul Joseph Davis commented on COUCHDB-220:
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I think we need a slight change in case someone lies to us:
From:
+ case NextAlloc of
+ 0 -> NewSize = lists:max([MinAlloc, size(Bin)]);
+ _ -> NewSize = NextAlloc
+ end,
To:
+ case NextAlloc of
+ 0 -> NewSize = lists:max([MinAlloc, size(Bin)]);
+ _ -> NewSize = lists:max([NextAlloc, size(Bin)])
+ end,
Otherwise we could end up writing beyond the allocated space if something gets
confused.
> 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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