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From w00t w00t <w00...@yahoo.de>
Subject Re: Hive and Lzo Compression
Date Mon, 19 Aug 2013 08:06:20 GMT
My scenario is a bit different - I am using external tables.

So I uploaded some lzo compressed files into HDFS, generated the lzo-index files and finally
I created the external table without the specific storage as clause .
A SELECT statement on the table still works.

Does it work transparently? So, Hadoop sees the lzo extension of my files and knows how to
decompress it?





________________________________
 Von: Nitin Pawar <nitinpawar432@gmail.com>
An: "user@hive.apache.org" <user@hive.apache.org> 
Gesendet: 19:54 Mittwoch, 14.August 2013
Betreff: Re: Hive and Lzo Compression
 


Please correct me if I understood the question correctly 
You created a table def without mentioning a stored as clause 
then you load data into table from a compressed a file 
then do a select query and it still works 
but how did it figured out which compression codec to use? 

Am I stating it correctly ? 




On Wed, Aug 14, 2013 at 11:11 PM, Sanjay Subramanian <Sanjay.Subramanian@wizecommerce.com>
wrote:

That is really interesting…let me try and think of a reason…meanwhile any other LZO Hive
Samurais out there ? Please help with some guidance
>
>
>sanjay 
>
>From: w00t w00t <w00tel@yahoo.de>
>Reply-To: "user@hive.apache.org" <user@hive.apache.org>, w00t w00t <w00tel@yahoo.de>
>Date: Wednesday, August 14, 2013 1:15 AM
>
>To: "user@hive.apache.org" <user@hive.apache.org>
>Subject: Re: Hive and Lzo Compression
>
>
>
>
>
>Thanks for your reply.
>
>
>The interesting thing I experience is that the SELECT query still works - even when I
do not specify the STORED AS clause... that puzzles me a bit.
>
>
>
>
>________________________________
> Von: Sanjay Subramanian <Sanjay.Subramanian@wizecommerce.com>
>An: "user@hive.apache.org" <user@hive.apache.org>; w00t w00t <w00tel@yahoo.de>

>Gesendet: 3:44 Mittwoch, 14.August 2013
>Betreff: Re: Hive and Lzo Compression
>
>
>
>Hi 
>
>
>I think the CREATE TABLE without the STORED AS clause will not give any errors while creating
the table.
>However when you query that table and since that table contains .lzo files , you would
 get errors. 
>With external tables , u r separating the table creation(definition) from the data. So
only at the time of query of that table, hive might report errors.
>
>
>LZO compression rocks ! I am so glad I used it in our projects here.
>
>
>Regards
>
>
>sanjay 
>
>From: w00t w00t <w00tel@yahoo.de>
>Reply-To: "user@hive.apache.org" <user@hive.apache.org>, w00t w00t <w00tel@yahoo.de>
>Date: Tuesday, August 13, 2013 12:13 AM
>To: "user@hive.apache.org" <user@hive.apache.org>
>Subject: Re: Hive and Lzo Compression
>
>
>
>Thanks for your replies and the link.
>
>
>I could get it working, but wondered why the CREATE TABLE statement worked without the
STORED AS Clause as well...that's what puzzles me a bit...
>
>
>But I will use the STORED AS Clause to be on the safe side.
>
>
>
>
>
>
>________________________________
> Von: Lefty Leverenz <leftyleverenz@gmail.com>
>An: user@hive.apache.org 
>CC: w00t w00t <w00tel@yahoo.de> 
>Gesendet: 19:06 Samstag, 10.August 2013
>Betreff: Re: Hive and Lzo Compression
>
>
>
>I'm not seeing any documentation link in Sanjay's message, so here it is again (in the
Hive wiki's language manual):  https://cwiki.apache.org/confluence/display/Hive/LanguageManual+LZO.

>
>
>
>On Thu, Aug 8, 2013 at 3:30 PM, Sanjay Subramanian <Sanjay.Subramanian@wizecommerce.com>
wrote:
>
>Please refer this documentation here
>>Let me know if u need more clarifications so that we can make this document better
and complete
>>
>>
>>Thanks
>>
>>
>>sanjay
>>
>>From: w00t w00t <w00tel@yahoo.de>
>>Reply-To: "user@hive.apache.org" <user@hive.apache.org>, w00t w00t <w00tel@yahoo.de>
>>Date: Thursday, August 8, 2013 2:02 AM
>>To: "user@hive.apache.org" <user@hive.apache.org>
>>Subject: Hive and Lzo Compression
>>
>>
>>
>>
>>
>>Hello,
>> 
>>I am started to run Hive with Lzo compression on Hortonworks 1.2
>> 
>>I have managed to install/configure Lzo and  hive -e "set io.compression.codecs"
shows me the Lzo Codecs:
>>io.compression.codecs=
>>org.apache.hadoop.io.compress.GzipCodec,
>>org.apache.hadoop.io.compress.DefaultCodec,
>>com.hadoop.compression.lzo.LzoCodec,
>>com.hadoop.compression.lzo.LzopCodec,
>>org.apache.hadoop.io.compress.BZip2Codec
>> 
>>However, I have some questions where I would be happy if you could help me.
>>(1) CREATE TABLE statement
>>
>>
>>I read in different postings, that in the CREATE TABLE statement, I have to use the
following STORAGE clause:
>> 
>>CREATE EXTERNAL TABLE txt_table_lzo (
>>   txt_line STRING
>>)
>>ROW FORMAT DELIMITED FIELDS TERMINATED BY '||||'
>>STORED AS INPUTFORMAT 'com.hadoop.mapred.DeprecatedLzoTextInputFormat' OUTPUTFORMAT
'org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat'
>>LOCATION '/user/myuser/data/in/lzo_compressed';
>> 
>>It works withouth any problems now to execute SELECT statements on this table with
Lzo data.
>> 
>>However I also created a table on the same data without this STORAGE clause:
>> 
>>CREATE EXTERNAL TABLE txt_table_lzo_tst (
>>   txt_line STRING
>>)
>>ROW FORMAT DELIMITED FIELDS TERMINATED BY '||||'
>>LOCATION '/user/myuser/data/in/lzo_compressed';
>> 
>>The interesting thing is, it works as well, when I execute a SELECT statement and
this table.
>> 
>>Can you help, why the second CREATE TABLE statement works as well?
>>What should I use in DDLs? 
>>Is it best practice to use the STORED AS clause with a "deprecatedLzoTextInputFormat"?
Or should I remove it?
>> 
>> (2) Output and Intermediate Compression Settings 
>> 
>>I want to use output compression .
>> 
>>In "Programming Hive" from Capriolo, Wampler, Rutherglen the following commands are
recommended:
>>SET hive.exec.compress.output=true;
>>SET mapred.output.compression.codec=com.hadoop.compression.lzo.LzopCodec;
>> 
>>           However, in some other places in forums, I found the following
recommended settings:
>>SET hive.exec.compress.output=true
>>SET mapreduce.output.fileoutputformat.compress=true
>>SET mapreduce.output.fileoutputformat.compress.codec=com.hadoop.compression.lzo.LzopCodec
>> 
>>Am I right, that the first settings are for Hadoop versions prior 0.23?
>>Or is there any other reason why the settings are different?
>> 
>>I am using Hadoop 1.1.2 with Hive 0.10.0.
>>Which settings would you recommend to use?
>> 
>>--------------
>>           I also want to compress intermediate results.
>>          
>>          Again, in  "Programming Hive" the following settings are recommended:
>>          SET hive.exec.compress.intermediate=true;
>>          SET mapred.map.output.compression.codec=com.hadoop.compression.lzo.LzopCodec;
>> 
>>           Is this the right setting?
>>
>>          Or should I again use the settings (which look more valid for Hadoop
0.23 and greater)?:
>>          SET hive.exec.compress.intermediate=true;
>>           SET mapreduce.map.output.compression.codec=com.hadoop.compression.lzo.LzopCodec;
>> 
>>Thanks
>> 
>>
>>
>>
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>
>
>
>
-- Lefty 
>
>
>
>CONFIDENTIALITY NOTICE
>======================
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>This email message and any attachments are for the exclusive use of the intended recipient(s)
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or distribution is prohibited. If you are not the intended recipient,
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-- 
Nitin Pawar
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