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From "Jonathan Ellis (JIRA)" <j...@apache.org>
Subject [jira] Commented: (CASSANDRA-2039) LazilyCompactedRow doesn't add CFInfo to digest
Date Sat, 05 Feb 2011 20:39:30 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-2039?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12991050#comment-12991050
] 

Jonathan Ellis commented on CASSANDRA-2039:
-------------------------------------------

Committed v2.  Thanks!

bq. what would be the impact of using estimatedColumnCount here instead

It would break the part of CompactionIterator that leaves out rows with no columns from the
new SSTable.  "estimated" is the maximum possible number of columns in the new row, so it's
ok to use it in the bloom filter, but not in the "is this row empty post-merge" check.

> LazilyCompactedRow doesn't add CFInfo to digest
> -----------------------------------------------
>
>                 Key: CASSANDRA-2039
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-2039
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Core
>    Affects Versions: 0.7.0
>            Reporter: Richard Low
>            Priority: Minor
>             Fix For: 0.8
>
>         Attachments: trunk-2038-LazilyCompactedRowTest.txt, trunk-2038-v2.txt, trunk-2038.txt
>
>
> LazilyCompactedRow.update doesn't add the CFInfo or columnCount to the digest, so the
hash value in the Merkle tree does not include this data.  However, PrecompactedRow does include
this.  Two consequences of this are:
> * Row-level tombstones are not compared when using LazilyCompactedRow so could remain
inconsistent
> * LazilyCompactedRow and PrecompactedRow produce different hashes of the same row, so
if two nodes have differing in_memory_compaction_limit_in_mb values, rows of size in between
the two limits will have different hashes so will always be repaired even when they are the
same.

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