Johannes Schwenk created PIG-2751:
-------------------------------------
Summary: Allow macros in FOREACH
Key: PIG-2751
URL: https://issues.apache.org/jira/browse/PIG-2751
Project: Pig
Issue Type: Improvement
Components: parser
Affects Versions: 0.10.0
Environment: Kubuntu 12.04 64Bit
Reporter: Johannes Schwenk
I would like to be able to use macros within the GENERATE of an FOREACH.
Example:
{code}
define test_macro(param1, param2) returns ret_val {
$ret_val = (param1 == 0 ? param2 : param1);
};
a = LOAD ('data') AS (id, val1, val2);
b = FOREACH a GENERATE id, test_macro(val1, val2);
DUMP b;
{code}
This would be most useful for having only a single point to edit (the macro) if
a definition for a special computation changes. Lets say, you have raw log data
and several scripts loading it. All scripts need to filter out specific unused
columns. Most (but not all) of the scripts are dealing with a field that needs
to be handled in a special way. So I cannot just use two different LOAD
functions (one with the special computation and one without) because that would
make a second FOREACH ... GENERATE necessary to filter out the unused columns.
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