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https://issues.apache.org/jira/browse/GORA-65?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13173607#comment-13173607
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Keith Turner commented on GORA-65:
----------------------------------
Oh one other major difference is paritioning a query. I will explain this by
example. Suppose I have an gora-accumulo table where the key is a long.
Suppose this table has the following splits. There are two reasons these split
points are not 8 bytes. Users can insert split points. Also, when Accumulo
chooses a split point, it will choose the shortest possible string. So split
point do not always come from rows in the table.
{noformat}
0x20
0x60
{noformat}
When partitioning a query over the entire table, I have to take the 2 splits
above and generate three partition queries that cover the entire table but do
not overlap. Also the queries need to align exactly with accumulo tablets (like
HBase regions) to maintain locality. The fact that the split points are not 8
byte also makes it tricky, they will not decode as a long. So I generate three
gora queries with the following start and end keys. These queries cover all
possible longs in the table. The queries map to accumulo tablets which have
exclusive start and inclusive end keys.
{noformat}
query 1 start key=null end key=0x1fffffffffffffff
query 2 start key=0x2000000000000000 end key=0x5fffffffffffffff
query 3 start key=0x6000000000000000 end key=null
{noformat}
When the key is not fixed width (like a long or int) and its a String, then its
much easier to create the partition queries.
> Implement Accumulo datastore for Gora
> -------------------------------------
>
> Key: GORA-65
> URL: https://issues.apache.org/jira/browse/GORA-65
> Project: Gora
> Issue Type: New Feature
> Reporter: Keith Turner
> Attachments: GORA-65-1.patch
>
>
> Accumulo is a BigTable implementation similar to HBase. Accumulo would be a
> great fit for another Gora datastore.
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