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From "Doug Cutting (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (AVRO-1259) improve Trevni encoding of sparse fields
Date Sat, 02 Mar 2013 00:21:13 GMT

    [ https://issues.apache.org/jira/browse/AVRO-1259?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13591139#comment-13591139
] 

Doug Cutting commented on AVRO-1259:
------------------------------------

Note that if you project a ["null", "int"] union down to simply ["int"] then Trevni only processes
the int column and sets the value of the field to null for rows where it has a non-int value.
                
> improve Trevni encoding of sparse fields
> ----------------------------------------
>
>                 Key: AVRO-1259
>                 URL: https://issues.apache.org/jira/browse/AVRO-1259
>             Project: Avro
>          Issue Type: Improvement
>          Components: trevni
>            Reporter: Doug Cutting
>         Attachments: AVRO-1259.patch
>
>
> If in most records a field is null, Trevni writes a null byte (zero length) for that
record in that column.  This might be optimized by instead using a run-length encoding for
lengths.  The length is signed, so negative lengths might be used to indicate the number of
zero-lengths before the next non-zero value.  This could thus be back-compatible.

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