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https://issues.apache.org/jira/browse/COUCHDB-465?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12745438#action_12745438
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Bob Dionne commented on COUCHDB-465:
------------------------------------
Robert,
sorry for the confusion, there are 4 tests there, tests 2 and 4 use the old
random and the new "sequential random" codes respectively. So I'm comparing:
precompact: 50020852 postcompact: 6099042
to
precompact: 52517614 postcompact: 2506850
That's why I used the phrase "sequentially random". Sequential in these tests
(1 and 3) means 1,2,3....
I agree about the batching, the diffs are almost noise with a batch size of
1000, which is what the compactor uses.
Cheers,
Bob
> 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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