[jira] Commented: (PIG-1473) Avoid serialization/deserialization costs for PigStorage data - Use custom Map and Bag implementation

["Jeff Zhang (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/PIG-1473?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12883382#action_12883382 ] 

Jeff Zhang commented on PIG-1473:
---------------------------------

This sounds like the lazy deserialization in Hive, Great !

> Avoid serialization/deserialization costs for PigStorage data - Use custom Map and Bag implementation
> -----------------------------------------------------------------------------------------------------
>
>                 Key: PIG-1473
>                 URL: https://issues.apache.org/jira/browse/PIG-1473
>             Project: Pig
>          Issue Type: Improvement
>    Affects Versions: 0.8.0
>            Reporter: Thejas M Nair
>            Assignee: Thejas M Nair
>             Fix For: 0.8.0
>
>
> Cost of serialization/deserialization (sedes) can be very high and avoiding it will improve performance.
> Avoid sedes when possible by implementing approach #3 proposed in http://wiki.apache.org/pig/AvoidingSedes .
> The load function uses subclass of Map and DataBag which holds the serialized copy.  LoadFunction delays deserialization of map and bag types until a member function of java.util.Map or DataBag is called. 
> Example of query where this will help -
> {CODE}
> l = LOAD 'file1' AS (a : int, b : map [ ]);
> f = FOREACH l GENERATE udf1(a), b;      
> fil = FILTER f BY $0 > 5;
> dump fil; -- Serialization of column b can be delayed until here using this approach .
> {CODE}

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