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From "Tim Williams (JIRA)" <>
Subject [jira] [Commented] (BLUR-55) Pluggable sharding strategy
Date Sun, 20 Jan 2013 01:48:12 GMT


Tim Williams commented on BLUR-55:

I wonder if there's a real use-case for a client-determined per update shard assignment? 
In other words, I like the idea of a pluggable sharding strategy, but I don't see why it's
not pluggable on the server conf - or a part of the table descriptor maybe?

If we do keep the current approach, it seems like making the shard assignment per-document
would be better than on the MutationOption (where "better" means more client-friendly:)) ?

Though, maybe I'm missing something because I don't yet understand how the mutation shardindex
assignment marries with the retrieval (doc thrift function).  Is the shard assignment somehow
packed in the docLocation?

> Pluggable sharding strategy
> ---------------------------
>                 Key: BLUR-55
>                 URL:
>             Project: Apache Blur
>          Issue Type: Bug
>    Affects Versions: 0.2.0
>            Reporter: Tim Williams
> The 0.2-dev code currently is driven from the client.  We should make the sharding strategy
pluggable so that someone who needs something more than a typical modulo on the docid over
the shard count can do it. 
> From Aaron's response[1]:
> "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."
> [1] -

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