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https://issues.apache.org/jira/browse/CASSANDRA-8959?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14358508#comment-14358508
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Benedict commented on CASSANDRA-8959:
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bq. and what Aleksey describes is pretty close to things that CASSANDRA-8099
currently does as it happens
Yes, although a little closer to what I outlined in 7447, but they're all
shades of the same coin. This was kind of my point - we should design an
approach that we consider optimal, preferably abstract it, and use the same
tool in each place, including here.
FTR, I think the encoding (for both) should include a flag in the row header
that encodes the kind of encoding, which should itself be either a header
bitmap for inclusion, a bitmap for exclusion, or a sequence of name ids
(denormalised in the same manner as column names for a table), and this
approach should be used for the table format as well. I think it should be
based on the schema at the time, not the fields present in the table, so that
this mapping can be "interned".
> More efficient frozen UDT and tuple serialization format
> --------------------------------------------------------
>
> Key: CASSANDRA-8959
> URL: https://issues.apache.org/jira/browse/CASSANDRA-8959
> Project: Cassandra
> Issue Type: Improvement
> Reporter: Aleksey Yeschenko
> Labels: performance
> Fix For: 3.1
>
>
> The current serialization format for UDTs has a fixed overhead of 4 bytes per
> defined field (encoding the size of the field).
> It is inefficient for sparse UDTs - ones with many defined fields, but few of
> them present. We could keep a bitset to indicate the missing fields, if any.
> It's sub-optimal for encoding UDTs with all the values present as well. We
> could use varint encoding for the field sizes of blob/text fields and encode
> 'fixed' sized types directly, without the 4-bytes size prologue.
> That or something more brilliant. Any improvement right now is lhf.
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