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https://issues.apache.org/jira/browse/COUCHDB-465?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12745429#action_12745429
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Robert Newson commented on COUCHDB-465:
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Bob,
I read your gist and the pre-compact size for sequential is smaller than for
random (43,144,791 vs 52,517,614) and post-compaction was smaller for
sequential too (2,023,522 vs 2,506,850). Perhaps you read the numbers the wrong
way around? Or did I? :)
I also note that most of this compaction is from not batching as you'll have a
4k footer block for each write. With ?batch=ok and sequential (and no
deletions) I find compaction to be only a marginal reduction of space.
> Produce sequential, but unique, document id's
> ---------------------------------------------
>
> Key: COUCHDB-465
> URL: https://issues.apache.org/jira/browse/COUCHDB-465
> Project: CouchDB
> Issue Type: Improvement
> Reporter: Robert Newson
> Attachments: couch_uuids.patch, uuid_generator.patch
>
>
> Currently, if the client does not specify an id (POST'ing a single document
> or using _bulk_docs) a random 16 byte value is created. This kind of key is
> particularly brutal on b+tree updates and the append-only nature of couchdb
> files.
> Attached is a patch to change this to a two-part identifier. The first part
> is a random 12 byte value and the remainder is a counter. The random prefix
> is rerandomized when the counter reaches its maximum. The rollover in the
> patch is at 16 million but can obviously be changed. The upshot is that the
> b+tree is updated in a better fashion, which should lead to performance
> benefits.
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