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From Apache Wiki <>
Subject [Couchdb Wiki] Update of "Document runner plugin" by MartinCzura
Date Sun, 02 Nov 2008 01:49:30 GMT
Dear Wiki user,

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The following page has been changed by MartinCzura:

The comment on the change is:
page creation

New page:
A Document Runner would provide functionality to run a transform function across all documents
in the database. This way you could do maintenance and migrations, with incurring a bunch
of http overhead.

The idea [
was originally floated on the couchdb-user mailing list].

=== Requirements ===

Ability to specify a job in a view-server like context (Javascript other language function)
and have it run across all docs (like a view is), but with the additional ability to write
back to the document (through the http api, so we don't have to add a socket-based update


We may not be able to guarantee that runner functions see each document only once, so functions
need to be aware only to modify documents that require modification.

=== Uses ===

 * Changing the format of a timestamp across all docs
 * Removing sensitive fields before replicating to another jurisdiction
 * (View runner... slightly different) Materializing the results of group=true reduce queries
into a dataset for further map/reduce processing (a common pattern in Hadoop)

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