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From "Robert Newson (JIRA)" <j...@apache.org>
Subject [jira] Commented: (COUCHDB-1009) Make couch_stream buffer configurable
Date Mon, 03 Jan 2011 14:44:45 GMT

    [ https://issues.apache.org/jira/browse/COUCHDB-1009?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12976762#action_12976762
] 

Robert Newson commented on COUCHDB-1009:
----------------------------------------

"it will be better to use it with even larger sizes (512Kb, 1Mb for example). "

Except that this will block concurrent writers from making progress (I need *you* to transmit
1mb before I can transmit my 1mb), etc.

Increasing from 4k seems a no-brainer to me though when I experimented with larger buffer
sizes a while ago (a year?) I found that things were little improved, matching your numbers.

I would be interested in knowing if it helps with compaction, though, since reading and writing
larger attachment blocks should really help.


> Make couch_stream buffer configurable
> -------------------------------------
>
>                 Key: COUCHDB-1009
>                 URL: https://issues.apache.org/jira/browse/COUCHDB-1009
>             Project: CouchDB
>          Issue Type: Improvement
>          Components: Database Core
>         Environment: trunk
>            Reporter: Filipe Manana
>            Assignee: Filipe Manana
>            Priority: Trivial
>         Attachments: COUCHDB-1009.patch
>
>
> The couch_stream buffer is hardcoded to 4Kb.
> This value should be configurable. Larger values can improve write and specially read
performance (if we write larger chunks to disk, we have higher chances of reading more contiguous
disk blocks afterwards). 
> I also think it's a good idea to change the default value from 4Kb to something higher
(64Kb for e.g.).
> Patch attached

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