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From "Stu Hood (JIRA)" <j...@apache.org>
Subject [jira] Issue Comment Edited: (CASSANDRA-1142) redesign hinted handoff schema
Date Fri, 04 Jun 2010 16:08:58 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-1142?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12875643#action_12875643
] 

Stu Hood edited comment on CASSANDRA-1142 at 6/4/10 12:08 PM:
--------------------------------------------------------------

> A thought, though: perhaps we should either store the token instead of ep... a hint could
be stored for a very long time
Another way to solve this would be for the HH table to have row keys == to the hinted row
keys. The query to determine all hinted rows for a particular endpoint would be a get_range_slice
call for the endpoint's current token range.

EDIT: So the full schema would be:
* Row keys are keys for which we have hinted data.
* Column names are Keyspace + CF names, joined with a '-'

      was (Author: stuhood):
    > A thought, though: perhaps we should either store the token instead of ep... a hint
could be stored for a very long time
Another way to solve this would be for the HH table to have row keys == to the hinted row
keys. The query to determine all hinted rows for a particular endpoint would be a get_range_slice
call for the endpoint's current token range.
  
> redesign hinted handoff schema
> ------------------------------
>
>                 Key: CASSANDRA-1142
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-1142
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>            Reporter: Jonathan Ellis
>            Assignee: Brandon Williams
>             Fix For: 0.7
>
>         Attachments: 1142.txt
>
>
> Currently, the HH schema looks like this:
>  * For each table (keyspace), there is a row in the system hints CF.
>  * SuperColumns in that row are keys for which we have hinted data.
>  * Subcolumns names within that supercolumn are host IPs. Subcolumn values are always
empty.
>  * Instead, we store the row data "normally" in the application table it belongs in.
> This has the drawback that we need to scan the entire hints data set to deliver hints
to a given endpoint.  I propose instead we do this:
>  * Row keys are endpoints for which we have hints.
>  * SuperColumns in that row are keys for which we have hinted data.
>  * Subcolumns names within that supercolumn are Keyspace + CF names, joined with a '-'
(which is an illegal character in CF names, so it's safe to use here)
> This makes looking up hints for a single endpoint efficient, as well as making it so
we only have to read data from CFs for which we actually have data for the key.
> Actual row data continues to be stored in application tables.
> Makes sense to do this after CASSANDRA-1141.

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