Re: Some optimization advices

[Jerome Pierson]

Thaks a lot. It works fine.

But one more point, I have only one mapper running with this pig job as 
my cluster has 4 slaves.
How could it be different ?
Regards,
Jérôme


Le 31/01/2013 20:45, Cheolsoo Park a écrit :
Hi Jerome,

Try this:

XmlTag = FOREACH xmlToTuple GENERATE FLATTEN ($0);
XmlTag2 = FOREACH XmlTag {
     tag_with_amenity = FILTER tag BY (tag_attr_k == 'amenity');
     GENERATE *, COUNT(tag_with_amenity) AS count;
};
XmlTag3 = FOREACH (FILTER XmlTag2 BY count > 0) GENERATE node_attr_id,
node_attr_lon, node_attr_lat, tag;

Thanks,
Cheolsoo


On Thu, Jan 31, 2013 at 9:19 AM, Jerome Pierson
<jerome.pier...@hurence.com>wrote:

Hi There,

I am a beginner, I achieved something, but I guess I could have done
better. Let me explain.
(Pig 0.10)

My data is DESCRIBE as :

  xmlToTuple: {(node_attr_id: int,node_attr_lon: chararray,node_attr_lat:
chararray,tag: {(tag_attr_k: chararray,tag_attr_v: chararray)})}


and DUMP like this :

((100312088,45.2745669,-12.**7776222,{(created_by,JOSM)}))
((100948454,45.2620946,-12.**7849171,))
((100948519,45.2356985,-12.**7707014,{(created_by,JOSM)}))
((704398904,45.2416667,-13.**0058333,{(lat,-13.00583333),(**
lon,45.24166667)}))
((1230941976,45.0743117,-12.**6888807,{(place,village)}))
((1230941977,45.0832807,-12.**6810328,{(name,Mtsahara)}))
((1976927219,45.2272263,-12.**7794359,))
((1751057677,45.2216163,-12.**7825896,{(amenity,fast_food),(**
name,Brochetterie)}))
((1751057678,45.2216953,-12.**7829678,{(amenity,fast_food),(**
name,Brochetterie)}))
((100948360,45.2338541,-12.**7762230,{(amenity,ferry_**terminal)}))
((362795028,45.2086809,-12.**8062991,{(amenity,fuel),(**operator,Total)}))

I want to extract the record which have a certain value for the tag_attr_k
field. For example, give me the record where there is a tag_attr_k =
amesity ? That should be :

(100948360,-12.7762230,45.**2338541,{(amenity,ferry_**terminal)})
(362795028,-12.8062991,45.**2086809,{(operator,Total),(**amenity,fuel)})
(1751057677,-12.7825896,45.**2216163,{(amenity,fast_food),(**
name,Brochetterie)})
(1751057678,-12.7829678,45.**2216953,{(amenity,fast_food),(**
name,Brochetterie)})

So (node_attr_id, node_attr_lat , node_attr_lon,{(tag_attr_k,
tag_attr_v)...(tag_attr_k,tag_**attr_v)}

I ended up with this script.


...
XmlTag = foreach xmlToTuple GENERATE FLATTEN ($0); --removed top including
level bag
XmlTag2 = foreach XmlTag GENERATE $0 as id, $1 as lon, $2 as lat, FLATTEN
(tag) as (key, value); --flatten the bag of tags
XmlTag3 =  FILTER XmlTag2 BY key == 'amenity'; -- get all the records with
amenity tags
XmlTag4 = JOIN XmlTag3 BY id, XmlTag2 BY id; -- re-build records with all
tags containing amenity tag
XmlTag7 = foreach XmlTag4 GENERATE $0 as id,$1 as lon, $2 as lat,$8 as
key, $9 as value; -- re-build records : removing redundant field
XmlTag5 = GROUP XmlTag7 BY (id,lat,lon); -- re-build records : grouping
redundant records
XmlTag8 = foreach XmlTag5 { --rebuild records : id,lat,long
{(key,value)...(key,value)}
         tag = foreach XmlTag7 GENERATE  key, value;
     GENERATE group.id,group.lat,group.lon,**tag;
};

Using this variable:

xmlToTuple: {(node_attr_id: int,node_attr_lon: chararray,node_attr_lat:
chararray,tag: {(tag_attr_k: chararray,tag_attr_v: chararray)})}
XmlTag: {null::node_attr_id: int,null::node_attr_lon:
chararray,null::node_attr_lat: chararray,null::tag: {(tag_attr_k:
chararray,tag_attr_v: chararray)}}
XmlTag2: {id: int,lon: chararray,lat: chararray,key: chararray,value:
chararray}
XmlTag3: {id: int,lon: chararray,lat: chararray,key: chararray,value:
chararray}
XmlTag4: {XmlTag3::id: int,XmlTag3::lon: chararray,XmlTag3::lat:
chararray,XmlTag3::key: chararray,XmlTag3::value: chararray,XmlTag2::id:
int,XmlTag2::lon: chararray,XmlTag2::lat: chararray,XmlTag2::key:
chararray,XmlTag2::value: chararray}
XmlTag7: {id: int,lon: chararray,lat: chararray,key: chararray,value:
chararray}
XmlTag5: {group: (id: int,lat: chararray,lon: chararray),XmlTag7: {(id:
int,lon: chararray,lat: chararray,key: chararray,value: chararray)}}
XmlTag8: {id: int,lat: chararray,lon: chararray,tag: {(key:
chararray,value: chararray)}}


I guess this not very straightforward and can be largely optimized. Please
give me some hints ?

Regards,
Jérôme