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https://issues.apache.org/jira/browse/COUCHDB-465?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12745396#action_12745396
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Bob Dionne commented on COUCHDB-465:
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I tested this all against a clean checkout of trunk and it looks good. The new
algorithm is faster on inserts[1] but interestingly for single inserts is makes
for a larger db pre-compact. After compaction the db is smaller by a factor of
3
I thought we leave the new "sequentially random" as the default? Paul, is the
concern just what's advertised to users?
Algorithms based on the system clock I think can be problematic as they assume
all machines have the correct time.
[1] http://gist.github.com/170982
> 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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