Two Phases :
Acquisition Phase :
PE sends Blocks to Each AMP in round robin.
AMPS hash and re-distributes to appropriate AMPs.
Records are written to AMP spool file .the records are un sorted.
Application Phase :
This Phase starts once END LOADING is encountered
Each AMP sort spool file and creates data blocks.
Writes data blocks to disk.
Fallback rows generated if required.
