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https://issues.apache.org/jira/browse/OMID-131?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16816843#comment-16816843
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Lars Hofhansl commented on OMID-131:
------------------------------------
Here are two otherwise identical table. For TEST_T I used Tephra and for TEST_O
I used Omid:
{code:java}
27825496 27825496 /hbase/data/default/TEST_O
14622248 14622248 /hbase/data/default/TEST_T
{code}
The storage is nearly doubled. This also reflects in the scan times:
{code:java}
0: jdbc:phoenix:localhost> select count(*) from test_o;
+-----------+
| COUNT(1) |
+-----------+
| 262144 |
+-----------+
1 row selected (2.563 seconds)
0: jdbc:phoenix:localhost> select count(*) from test_t;
+-----------+
| COUNT(1) |
+-----------+
| 262144 |
+-----------+
1 row selected (0.72 seconds)
{code}
Both tables are fully flushed and compacted.
Not saying that Tephra is better (it's not, it has other issues), just that
there's a lot of room for improvement.
> Enhance row level conlict detection to reduce client memory footprint.
> ----------------------------------------------------------------------
>
> Key: OMID-131
> URL: https://issues.apache.org/jira/browse/OMID-131
> Project: Apache Omid
> Issue Type: Improvement
> Affects Versions: 1.0.1
> Reporter: Yonatan Gottesman
> Assignee: Yonatan Gottesman
> Priority: Major
> Time Spent: 20m
> Remaining Estimate: 0h
>
> Currently even if omid is working in row level conflict detection, all the
> cells are kept by the client until after commit for writing shadow cells or
> removing them after abort.
> Instead the client should store only the rows or only the family.
> If we choose to store only the row, the client memory footprint will be
> smaller, but if a region server wants to query a shadow cell for a cell it
> might have to query a different region.
> On the other hand client can store the famelies of a writeset. This will have
> a bigger footprint if we have lots of families but if a region queries a
> shadow cell it will be on the same region.
>
>
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