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Pig, mail # user - Problems with Join in pig


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Paltheru, Srikanth 2011-03-14, 21:40
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Thejas M Nair 2011-03-14, 23:18
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Paltheru, Srikanth 2011-03-14, 23:20
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Olga Natkovich 2011-03-15, 00:23
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Re: Problems with Join in pig
Thejas M Nair 2011-03-15, 00:29
Fragment-replicate join will also produce an efficient query plan for this use case - http://pig.apache.org/docs/r0.8.0/piglatin_ref1.html#Replicated+Joins . It is available in 0.5 as well.
-Thejas

On 3/14/11 3:20 PM, "Paltheru, Srikanth" <[EMAIL PROTECTED]> wrote:

I am using Pig 0.5 version. We don't have plans to upgrade it to a newer version. But the problem I have is the script runs for some files(both larger and smaller than the ones mentioned) but not for this particular one. I get "GC overhead limit" Error.
Thanks
Sri
-----Original Message-----
From: Thejas M Nair [mailto:[EMAIL PROTECTED]]
Sent: Monday, March 14, 2011 4:18 PM
To: [EMAIL PROTECTED]; Paltheru, Srikanth
Subject: Re: Problems with Join in pig

What version of pig are you using ? There have been some memory utilization fixes in 0.8 . For this use case, you can also use the new scalar feature in
0.8 -
http://pig.apache.org/docs/r0.8.0/piglatin_ref2.html#Casting+Relations+to+Sc
alars . That query plan will be more efficient.

You might want to build a new version of pig from svn 0.8 branch because there have been some bug fixes after the release -

svn co http://svn.apache.org/repos/asf/pig/branches/branch-0.8
cd branch-0.8
ant

-Thejas
On 3/14/11 1:40 PM, "Paltheru, Srikanth" <[EMAIL PROTECTED]>
wrote:

> The following pig script runs fine without the 2GB memory setting (see
> in yellow). But fails with memory setting. I am not sure what's
> happening. It's a simple operation of joining one tuple(of 1 row) with the other tuple.
> Here is what I am trying to do:
>
>  1.  grouping all SELECT HIT TIME DATA into a single tuple by doing a
> GROUP ALL.
>  2.  getting the min and max of that set and putting it into MIN HIT DATA.
> This is a tuple with a single row.
>  3.  then grouping SELECT MAX VISIT TIME DATA by visid,  4.  then
> generating  DUMMY_KEY  for every row, along with MAX of start time.
>  5.  then try to join the single tuple in 2 with all tuples generated
> in 4 to get a min time and a max time
>
> Code:
> Shell prompt:
> ## setting heap size to 2 GB
> PIG_OPTS="$PIG_OPTS -Dmapred.child.java.opts=-Xmx2048m"
> export PIG_OPTS
>
> Pig/Grunt
>
> RAW_DATA = LOAD
> '/omniture_test_qa/cleansed_output_1/2011/01/05/wdgesp360/wdgesp360_20
> 11-01-05
> *.tsv.gz' USING PigStorage('\t');
> FILTER_EXCLUDES_DATA = FILTER RAW_DATA BY $6 <= 0; SELECT_CAST_DATA > FOREACH FILTER_EXCLUDES_DATA GENERATE 'DUMMYKEY' AS
> DUMMY_KEY,(int)$0 AS hit_time_gmt, (long)$2 AS visid_high, (long)$3 AS
> visid_low, (chararray)$5 AS truncated_hit; SELECT_DATA = FILTER
> SELECT_CAST_DATA BY truncated_hit =='N';  --MIN AND MAX_HIT_TIME_GMT
> FOR THE FILE/SUITE SELECT_HIT_TIME_DATA = FOREACH SELECT_DATA GENERATE
> (int)hit_time_gmt; GROUPED_ALL_DATA = GROUP SELECT_HIT_TIME_DATA ALL
> PARALLEL 100; MIN_HIT_DATA = FOREACH GROUPED_ALL_DATA  GENERATE
> 'DUMMYKEY'AS
> DUMMY_KEY,MIN(SELECT_HIT_TIME_DATA.hit_time_gmt) AS
> MIN_HIT_TIME_GMT,MAX(SELECT_HIT_TIME_DATA.hit_time_gmt) AS
> MAX_HIT_TIME_GMT;  ---MAX_VISIT_START_TIME BY VISITOR_ID
> SELECT_MAX_VISIT_TIME_DATA =  FOREACH SELECT_DATA GENERATE
> visid_high,visid_low,visit_start_time_gmt;
> GROUP_BY_VISID_MAX_VISIT_TIME_DATA = GROUP SELECT_MAX_VISIT_TIME_DATA
> BY
> (visid_high,visid_low) PARALLEL 100;
> MAX_VISIT_TIME = FOREACH GROUP_BY_VISID_MAX_VISIT_TIME_DATA GENERATE
> 'DUMMYKEY' AS DUMMY_KEY,FLATTEN(group.visid_high) AS
> visid_high,FLATTEN(group.visid_low) AS visid_low,
> MAX(SELECT_MAX_VISIT_TIME_DATA.visit_start_time_gmt) AS
> MAX_VISIT_START_TIME; JOINED_MAX_VISIT_TIME_DATA = COGROUP
> MAX_VISIT_TIME BY DUMMY_KEY OUTER,MIN_HIT_DATA BY DUMMY_KEY OUTER
> PARALLEL 100; MIN_MAX_VISIT_HIT_TIME = FOREACH
> JOINED_MAX_VISIT_TIME_DATA GENERATE
> FLATTEN(MAX_VISIT_TIME.visid_high),FLATTEN(MAX_VISIT_TIME.visid_low),F
> LATTEN(M
> AX_VISIT_TIME.MAX_VISIT_START_TIME),FLATTEN(MIN_HIT_DATA.MIN_HIT_TIME_
> GMT),FLA
> TTEN(MIN_HIT_DATA.MAX_HIT_TIME_GMT);
>  DUMP MIN_MAX_VISIT_HIT_TIME;
>
>
> Can any one please guide me through this problem?
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Dmitriy Ryaboy 2011-03-15, 00:37
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Dmitriy Ryaboy 2011-03-15, 00:38
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Paltheru, Srikanth 2011-03-15, 00:41
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Thejas M Nair 2011-03-15, 00:54