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https://issues.apache.org/jira/browse/PIG-1473?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Thejas M Nair resolved PIG-1473.
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Resolution: Won't Fix
Implementing lazy de-serialization using this approach will introduce a non
backward compatible change in PigStorage . So closing this jira as wontfix.
In PigStorage, if the de-serialization fails, the value is treated as null, ie
tuple.get(i) returns null .
But if the de-serialization is delayed by returning a subclass of map or bag
that holds the serialized data, the tuple.get(i) call will return a non null
value even if the serialized format has a problem.
Though this approach is not being implemented in PigStorage() for this reason,
other load store functions can potentially adopt this method.
> 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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