Zebra, RC and Text size comparison

[Viraj Bhat <vi...@yahoo-inc.com>]

Hi all,

 I have some data in Zebra around 9 TB which I converted first to
PlainText using the TextOutputFormat in M/R and it resulted in around
43.07TB. [[I think I used no compression here.]]

I then later converted this data to RC using on the hive console as:

 

CREATE TABLE LARGERC

   ROW FORMAT SERDE
"org.apache.hadoop.hive.serde2.columnar.ColumnarSerDe"

   STORED AS RCFile

   LOCATION '/user/viraj/huge AS

SELECT * FROM PLAINTEXT;

 

(PLAINTEXT is the external table which is 43.07 TB in size) 

 

The overall sizes of these files were around 41.65 TB. I am suspecting
that some compression was not being applied.

 

I read the following documentation:

http://hadoop.apache.org/hive/docs/r0.4.0/api/org/apache/hadoop/hive/ql/
io/RCFile.html and it tells that: "The actual compression algorithm used
to compress key and/or values can be specified by using the appropriate
CompressionCodec"

 

a)       What is the default Codec that is being used? 

b)       Any thoughts on how I can reduce the size?

Viraj

Re: Zebra, RC and Text size comparison

[yongqiang he <he...@gmail.com>]

there is a config hive.exec.compress.output (pls double check) to
contry whether to compress final data or not.

Maybe you can just try to convert data directly from zebra    I sent
out some code to do that. Have u tried?

Also I think maybe it's good to first try to test on some small data
before try on such a large datasets.

On Friday, June 11, 2010, Viraj Bhat <vi...@yahoo-inc.com> wrote:
>
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> Hi all,
>
>  I have some data in Zebra around 9 TB which I
> converted first to PlainText using the TextOutputFormat in M/R and it resulted in
> around 43.07TB. [[I think I used no compression here.]]
>
> I then later converted this data to RC using on the hive
> console as:
>
>
>
> CREATE TABLE LARGERC
>
>    ROW FORMAT SERDE
> "org.apache.hadoop.hive.serde2.columnar.ColumnarSerDe"
>
>    STORED AS RCFile
>
>    LOCATION '/user/viraj/huge AS
>
> SELECT * FROM PLAINTEXT;
>
>
>
> (PLAINTEXT is the external table which is 43.07 TB in size)
>
>
>
> The overall sizes of these files were around 41.65 TB. I am
> suspecting that some compression was not being applied.
>
>
>
> I read the following documentation:
>
> http://hadoop.apache.org/hive/docs/r0.4.0/api/org/apache/hadoop/hive/ql/io/RCFile.html
> and it tells that: “The actual compression algorithm used to compress key
> and/or values can be specified by using the appropriate CompressionCodec”
>
>
>
> a)       What is the
> default Codec that is being used?
>
> b)       Any thoughts
> on how I can reduce the size?
>
> Viraj
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