Alan Gates commented on PIG-652:

Sorry, forgot to include the schema part.  A second function should be added to 
the StoreFunc interface:

     * Specify a schema to be used in storing the data.  This can be used by
     * store functions that store the data in a self describing format.  The
     * store function is free to ignore this if it cannot use it.
     * @param schema of the output data
    public void setStorageSchema(Schema s);

This function would be called during query planning.  The StoreFunc can then 
take the responsibility of storing away the schema so that it (or it's 
associated OutputFormat) can access it on the backend.  This schema will also 
include the sortedness of the data.

As for making the JobConf and path available those are passed to 
OutputFormat.getRecordWriter, so those implementing their own OutputFormats 
will have access to them.  They can then pass them on to their store functions 
as they wish.

For compression, pig right now has no way to communicate compression types 
other than file endings (.bz is the only one we support at the moment).  This 
is a kludge, but I don't want to propose a whole way to coherently communicate 
compression in pig at the moment.  So I vote that we stay with this for the 
time being.

> Need to give user control of OutputFormat
> -----------------------------------------
>                 Key: PIG-652
>                 URL: https://issues.apache.org/jira/browse/PIG-652
>             Project: Pig
>          Issue Type: New Feature
>          Components: impl
>            Reporter: Alan Gates
>            Assignee: Alan Gates
> Pig currently allows users some control over InputFormat via the Slicer and 
> Slice interfaces.  It does not allow any control over OutputFormat and 
> RecordWriter interfaces.  It just allows the user to implement a storage 
> function that controls how the data is serialized.  For hadoop tables, we 
> will need to allow custom OutputFormats that prepare output information and 
> objects needed by a Table store function.

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