[
https://issues.apache.org/jira/browse/CASSANDRA-3625?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13170057#comment-13170057
]
Boris Yen edited comment on CASSANDRA-3625 at 12/15/11 9:07 AM:
----------------------------------------------------------------
Not sure if this is doable or has any issue.
I am thinking why not mimic that way the secondary index is implemented right
now. Create one extra column family for keeping track of the comparators for
each row. So, whenever a column is inserted to the cassandra, the cassandra
needs to read before write to make sure the new column is valid. This would
sacrifice the write performance of dynamicComposite column family, but at least
it allows the cassandra to perform the validation before the actual write.
was (Author: yulinyen):
Not sure if this is doable or has an issue.
I am thinking why not mimic that way the secondary index is implemented right
now. Create one extra column family for keeping track of the comparators for
each row. So, whenever a column is inserted to the cassandra, the cassandra
needs to read before write to make sure the new column is valid. This would
sacrifice the write performance of dynamicComposite column family, but at least
it allows the cassandra to perform the validation before the actual write.
> Do something about DynamicCompositeType
> ---------------------------------------
>
> Key: CASSANDRA-3625
> URL: https://issues.apache.org/jira/browse/CASSANDRA-3625
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Reporter: Sylvain Lebresne
>
> Currently, DynamicCompositeType is a super dangerous type. We cannot leave it
> that way or people will get hurt.
> Let's recall that DynamicCompositeType allows composite column names without
> any limitation on what each component type can be. It was added to basically
> allow to use different rows of the same column family to each store a
> different index. So for instance you would have:
> {noformat}
> index1: {
> "bar":24 -> someval
> "bar":42 -> someval
> "foo":12 -> someval
> ...
> }
> index2: {
> 0:uuid1:3.2 -> someval
> 1:uuid2:2.2 -> someval
> ...
> }
> ....
> {noformat}
> where index1, index2, ... are rows.
> So each row have columns whose names have similar structure (so they can be
> compared), but between rows the structure can be different (we neve compare
> two columns from two different rows).
> But the problem is the following: what happens if in the index1 row above,
> you insert a column whose name is 0:uuid1 ? There is no really meaningful way
> to compare "bar":24 and 0:uuid1. The current implementation of
> DynamicCompositeType, when confronted with this, says that it is a user error
> and throw a MarshalException.
> The problem with that is that the exception is not throw at insert time, and
> it *cannot* be because of the dynamic nature of the comparator. But that
> means that if you do insert the wrong column in the wrong row, you end up
> *corrupting* a sstable.
> It is too dangerous a behavior. And it's probably made worst by the fact that
> some people probably think that DynamicCompositeType should be superior to
> CompositeType since you know, it's dynamic.
> One solution to that problem could be to decide of some random (but
> predictable) order between two incomparable component. For example we could
> design that IntType < LongType < StringType ...
> Note that even if we do that, I would suggest renaming the
> DynamicCompositeType to something that suggest that CompositeType is always
> preferable to DynamicCompositeType unless you're really doing very advanced
> stuffs.
> Opinions?
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators:
https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa
For more information on JIRA, see: http://www.atlassian.com/software/jira
