- Data types
- Nulls
In Pig a null data element means the value is unknown.which is completely different from the concept of null in C, Java, Python, etc.
- Schemas
dividends = load 'NYSE_dividends' as (exchange:chararray, symbol:chararray, date:chararray, dividend:float);
dividends = load 'NYSE_dividends' as (exchange, symbol, date, dividend); //bytearray
mdata = load 'mydata' using HCatLoader(); //load schema from HCatalog
- Type Casts
player= load 'baseball' as (name:chararray, team:chararray,pos:bag{t:(p:chararray)}, bat:map[]);
unintended = foreach player generate (int)bat#'base_on_balls' - (int)bat#'ibbs';
unintended = foreach player generate (int)bat#'base_on_balls' - (int)bat#'ibbs';
Casts to bytearrays are never allowed because Pig does not know how to represent the various data types in binary format. Casts from bytearrays to any type are allowed. Casts to and from complex types currently are not allowed, except from bytearray, although conceptually in some cases they could be.