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https://issues.apache.org/jira/browse/CASSANDRA-1938?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13003863#comment-13003863
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Sylvain Lebresne commented on CASSANDRA-1938:
---------------------------------------------
bq. Is there anyway to deal with this by tracking the CounterColumns in
-Statistics.db?
We don't even have to go there. We can have special casing for counter CFs if
need be. But it won't be super pretty. In particular, you'll have to special
case both PreCompactedRow and LazyCompactedRow. Because the main point is to
use the columns updateDigest() function to compute the preCompactedRow digests
instead of using the raw bytes. If you special case here, you'll have to mirror
this in the lazy case, that is, use the columns updateDigest in the counter
case, but the raw bytes otherwise.
However, what I'm trying to say is that I'm not super convinced that the
echoRow 'optimisation' is really that useful anymore (I'm not talking about
cleanup where echoing is useful and not changed by this patch). But during
compaction, we echo a row if it's only in one of the sstable we're compacting
*but* it also exists in a sstable we are not compacting (otherwise we still
deserialize for tombstone reclaiming). I would imagine we have either rows that
are often updated (in which case it will be rare to have only 1 of the sstable
we compact containing it) or rows that are barely updated (in which case we'll
still deserialize for tombstone reclaiming most of the time).
I'm also not sure we'll keep this 'optimization' forever anyway. If we add
checksums for example (which we should imho, sooner than later), echoing data
may not be desirable.
So given all this and given that even for the (I believe) rare cases where it
is useful, it is not in a critical path, I'd advise against polluting the code
for this.
That being said, if I'm the only one to feel that way, it's doable.
> Use UUID as node identifiers in counters instead of IP addresses
> -----------------------------------------------------------------
>
> Key: CASSANDRA-1938
> URL: https://issues.apache.org/jira/browse/CASSANDRA-1938
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Reporter: Sylvain Lebresne
> Assignee: Sylvain Lebresne
> Fix For: 0.8
>
> Attachments: 0001-Use-uuid-instead-of-IP-for-counters.patch,
> 0002-Merge-old-shard-locally.patch, 0003-Thrift-change-to-CfDef.patch,
> 1938_discussion
>
> Original Estimate: 56h
> Remaining Estimate: 56h
>
> The use of IP addresses as node identifiers in the partition of a given
> counter is fragile. Changes of the node's IP addresses can result in data
> loss. This patch proposes to use UUIDs instead.
> NOTE: this breaks the on-disk file format (for counters)
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