hadoop-pig-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Pradeep Kamath (JIRA)" <j...@apache.org>
Subject [jira] Commented: (PIG-879) Pig should provide a way for input location string in load statement to be passed as-is to the Loader
Date Thu, 19 Nov 2009 18:59:39 GMT

    [ https://issues.apache.org/jira/browse/PIG-879?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12780200#action_12780200
] 

Pradeep Kamath commented on PIG-879:
------------------------------------

In TestLoad.java it looks like a couple of tests have been commented since they should run
in local mode.
Since TestLoad is currently working in MAPREDUCE mode and we no longer support file:<path>
in MAPREDUCE mode, we
should probably change TestLoad to run each test in both local and map-red mode so we test
relative to absolute
path conversion in both modes.

I think there is a jira opened against hadoop to make the method to parse file globs public
- currently
the same code is in the patch - we should put a comment in the code that we should use Hadoop's
method when
the jira-XXXX is fixed 

While creating a LOStore in the QueryParser, we should be calling StoreFunc's relToAbsoluteStoreLocation()
method.
We should add a comment in StoreFunc interface that implementations can just use LoadFunc's
static methid to implement
this method.


> Pig should provide a way for input location string in load statement to be passed as-is
to the Loader
> -----------------------------------------------------------------------------------------------------
>
>                 Key: PIG-879
>                 URL: https://issues.apache.org/jira/browse/PIG-879
>             Project: Pig
>          Issue Type: Bug
>    Affects Versions: 0.3.0
>            Reporter: Pradeep Kamath
>            Assignee: Richard Ding
>         Attachments: PIG-879.patch, PIG-879.patch, PIG-879.patch, PIG-879.patch
>
>
>  Due to multiquery optimization, Pig always converts the filenames to absolute URIs (see
http://wiki.apache.org/pig/PigMultiQueryPerformanceSpecification - section about Incompatible
Changes - Path Names and Schemes). This is necessary since the script may have "cd .." statements
between load or store statements and if the load statements have relative paths, we would
need to convert to absolute paths to know where to load/store from. To do this QueryParser.massageFilename()
has the code below[1] which basically gives the fully qualified hdfs path
>  
> However the issue with this approach is that if the filename string is something like
"hdfs://localhost.localdomain:39125/user/bla/1,hdfs://localhost.localdomain:39125/user/bla/2",
the code below[1] actually translates this to hdfs://localhost.localdomain:38264/user/bla/1,hdfs://localhost.localdomain:38264/user/bla/2
and throws an exception that it is an incorrect path.
>  
> Some loaders may want to interpret the filenames (the input location string in the load
statement) in any way they wish and may want Pig to not make absolute paths out of them.
>  
> There are a few options to address this:
> 1)    A command line switch to indicate to Pig that pathnames in the script are all absolute
and hence Pig should not alter them and pass them as-is to Loaders and Storers. 
> 2)    A keyword in the load and store statements to indicate the same intent to pig
> 3)    A property which users can supply on cmdline or in pig.properties to indicate the
same intent.
> 4)    A method in LoadFunc - relativeToAbsolutePath(String filename, String curDir) which
does the conversion to absolute - this way Loader can chose to implement it as a noop.
> Thoughts?
>  

-- 
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.


Mime
View raw message