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From "Krishna Kumar (Commented) (JIRA)" <>
Subject [jira] [Commented] (HIVE-2604) Add UberCompressor Serde/Codec to contrib which allows per-column compression strategies
Date Mon, 05 Dec 2011 10:27:41 GMT


Krishna Kumar commented on HIVE-2604:

The current implementation works as follows:

 - Adds a serde UberCompressorSerde, which is used to convert the cell values to bytes
 - Adds a codec UberCompressionCodec which uses user-specific config to compress each block
of column values through one of three possible mechanisms
   - Config for the column: "codec:<codecname>" - Apply a CompressionCodec on the UberCompressorSerde
serialized bytestream
   - Config for the column: "codec:<codecname>,<serdename>" Re-serialize the bytestream
through serdename and then apply codecname on it
   - Config for the column: "compressor:<compressorname>" compress the cell values by
sending them through the type-specific compressor
   - [As a future enhancement, the config, say if is "dynamic", can let the codec decide the
mechanism on the current block stats/previous seen blocks]

 The idea is to maintain the ability to use a serde/codec combination (as we do now) for any
columns which are not 'interesting' and use type-specific compressors only for special columns.

 Type-specific compressor is also an extension point only; no implementation attached to this
jira. Have attached one sample compressor to HIVE-2623, while many others are possible. 


> Add UberCompressor Serde/Codec to contrib which allows per-column compression strategies
> ----------------------------------------------------------------------------------------
>                 Key: HIVE-2604
>                 URL:
>             Project: Hive
>          Issue Type: Sub-task
>          Components: Query Processor, Serializers/Deserializers
>            Reporter: Krishna Kumar
>            Assignee: Krishna Kumar
>         Attachments: HIVE-2604.v0.patch
> The strategies supported are
> 1. using a specified codec on the column
> 2. using a specific codec on the column which is serialized via a specific serde
> 3. using a specific "TypeSpecificCompressor" instance

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