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Date: Wed, 9 Mar 2011 05:40:59 +0000 (UTC)
From: "Damien Katz (JIRA)" <jira@apache.org>
To: dev@couchdb.apache.org
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Subject: [jira] Commented: (COUCHDB-1084) Remove unnecessary btree lookup
 inside couch_db_updater
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    [ https://issues.apache.org/jira/browse/COUCHDB-1084?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13004376#comment-13004376 ] 

Damien Katz commented on COUCHDB-1084:
--------------------------------------

This isn't the first time i've seen weird unexpected results from relaxamation. I'm really thinking the benchmarks need some work to be more usable and useful. I can't explain wonder how the the improvements on the write path would cause this read impact. Perhaps more comprehensive tests would give a clearer picture what's going on, or maybe there is a bug in the tests themselves.

I've also had a hard time interpreting the graphs, I think they need some smoothing or something to make it easier to visualize the differences.

> Remove unnecessary btree lookup inside couch_db_updater
> -------------------------------------------------------
>
>                 Key: COUCHDB-1084
>                 URL: https://issues.apache.org/jira/browse/COUCHDB-1084
>             Project: CouchDB
>          Issue Type: Improvement
>          Components: Database Core
>    Affects Versions: 1.2
>            Reporter: Damien Katz
>            Assignee: Damien Katz
>         Attachments: remove_btree_lookup.patch
>
>
> The CouchDB update process has an unnecessary btree lookup, where it reads the values in bulks, checks for conflicts, writes the docs to disk, updates the values appropriately and writes them to the btree out in a second step. It's possible to avoid this second step, and instead do all the checking, doc writing and value transformation in a single btree lookup, thereby reducing the number of btree traversals and disk IO.

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