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From Tim Williams <william...@gmail.com>
Subject Re: shards
Date Sun, 20 Jan 2013 01:06:30 GMT
On Sat, Jan 19, 2013 at 3:50 PM, Aaron McCurry <amccurry@gmail.com> wrote:
> It can. While its not implemented yet, I want to make a pluggable strategy.  Along with
controlling the layout it would also handle shard count changes, and if they are allowed.
>
> So a couple of strategies that I have been thinking about.
>
> -Hash based where it would hash on a pre-configured field.  Field would not be allowed
to be null and the number of shards would be fixed.  Also the shard placement provided by
the user would be ignored.
> -User based where the user has total control over the placement of the document by providing
it during indexing.  If a shard index is provided in an update and the current table does
not continue that shard, then a new one would be created and added to the table.
>
> As for now we are now somewhere in between.  The number of shards are fixed and it's
up to the user to provide the shard index.  I think (need to look at the code) if the user
provides a -1 then it randomly chooses a shard for the document. It's could be dangerous for
updates. We should create a jira issue to discuss further and provide a better implementation.

Cool, I added a JIRA(BLUR-55)[1] to discuss it.  Yeah, maybe require
an 'id' field and do a typical mod by shard count as a happier
default.

--tim

[1] - https://issues.apache.org/jira/browse/BLUR-55

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