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From "Jeff Jirsa (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-14089) Time Window Compaction Strategy: Determine window by column value
Date Fri, 01 Dec 2017 23:25:00 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-14089?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16275175#comment-16275175
] 

Jeff Jirsa commented on CASSANDRA-14089:
----------------------------------------

You've marked this as invalid, but there are two ways to do this without changing TWCS:

1) You can write data with {{USING TIMESTAMP}}, which will go into the old windows. You just
need care to only write one window at a time, and then {{flush}} between windows.

2) You can load the data from the old CF into the new by creating new sstables offline (see:
CQLSSTableWriter), and separate them into time windows offline as you create them. Then, load
into new table with {{sstableloader}} . 

> Time Window Compaction Strategy: Determine window by column value
> -----------------------------------------------------------------
>
>                 Key: CASSANDRA-14089
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-14089
>             Project: Cassandra
>          Issue Type: New Feature
>            Reporter: Taylor Cressy
>
> Recently, we came across an issue where we needed to repartition a column family and
alter it's compaction strategy to TWCS. 
> We wanted to ensure that the time series data was bucketized properly into it's appropriate
window when we migrate data from the old CF to the new one. However, there appears to be no
simple way to do this unless we:
> 1) Set the time window to some arbitrary length
> 2) Backload a chunk of the data within that time window 
> 3) After all chunks backload, reset the time window to the desired size
> I propose that we allow TWCS to have the ability to key off a column value for placing
it in a window. 
> Also, maybe we can adjust the TTL accordingly - based on that column value, upon insert
- considering TTLs and TWCS are generally based on some form of business logic. Of course,
the user could calculate the TTL on the fly, but it could be a nice feature.



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