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From "Alex Petrov (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-7190) Add schema to snapshot manifest
Date Mon, 23 May 2016 15:01:13 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-7190?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15296478#comment-15296478
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Alex Petrov commented on CASSANDRA-7190:
----------------------------------------

I've changed a syntax a bit, to be consistent with the rest of grammar: {{ALTER TABLE %s DROP
todrop USING TIMESTAMP 1;}}  as {{WITH}} keyword is already used in this statement for something
different (table attributes). It's also possible to specify a different timestamp for each
dropped column. 

The only pitfalls I currently see is that:
  * drop timestamp is recorded in microseconds, although then rounded to millisecond resolution.
  * when schema is updated, during announcement of migration, {{switchMemtable}} is called
and the table is flushed to SSTable with new metadata, which means that all the columns will
be lost during the write iteration. That might be unwanted behaviour, as if that'd be a feature
that could be used as [~slebresne] described (incrementally getting rid of data), on each
memtable flush all columns, disregarding timestamp, from that memtable, will be lost. Writing
dropped column data as well is possible, but in majority of cases will be an unnecessary effort.

Do we want keep it that way?

> Add schema to snapshot manifest
> -------------------------------
>
>                 Key: CASSANDRA-7190
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-7190
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Tools
>            Reporter: Jonathan Ellis
>            Assignee: Alex Petrov
>            Priority: Minor
>              Labels: lhf
>             Fix For: 3.x
>
>
> followup from CASSANDRA-6326



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