Frame for Exadata new Features

Make a note for Exadata new Features' frame:

A.Hybrid Columnar Compression
B.Exadata Smart Flash Cache                
C.Off Loading(*c1):
     1.Decompression(*c2)
    2.Decryption
    3.Rman: 1.Incremental Backups
                 2.Restores
     4.Datafile Initaliztion
    5.Simple Join
     6.Function
     7.Virural Column
     8.Smart Scan(*c3): 1.Predicate Filtering: =>1.Storage Index
                          2.Column Projection
                             


(*c1)Offloading three design goals:
• Reduce the volume of data transferred from disk systems to the database servers.
• Reduce CPU usage on database servers.
• Reduce disk access times at the storage layer.

(*c2)
Compression always Done at Database tier, while Decompression can be Done at storage tier.
Same to Encryption/Decryption.

(*c3)Four Necessary condition For Smart Scan:
• Must be Full Scan or Index Fast Full Scan
• Must be Direct Path Read: Parallel Query or Serial Query    
• Must have Predicate Filter or Column Projection
• Data must located on Exadata storage


Appendix A: Four kinds of HCC Compression Types
Name Level Type  Ratio
QUERY LOW HCC level 1 LZO 4×
QUERY HIGH HCC  level 2 ZLIB 6×
ARCHIVE LOW HCC level 3 ZLIB 7×
QUERY HIGH      level 4 BZIP2 14×

Appendix B: Commands related to Flash Card
alter table kso.skew3 storage (cell_flash_cache keep);
CellCLI> create flashcache all;
CellCLI> list flashcache detail
CellCLI> list celldisk attributes name, diskType, size where name like 'FD.*'
CellCLI> LIST METRICCURRENT WHERE objectType = 'FLASHCACHE';

Appendix C: parameter to control offload related Features
alter session set cell_offload_processing=true;
alter session set "_serial_direct_read"=true;
alter system set "_kcfis_storageidx_disabled"=false;
alter session set "_bloom_predicate_pushdown_to_storage"=true;
alter session set "_cell_offload_virtual_columns"=true;
alter system set _DISABLE_CELL_OPTIMIZED_BACKUPS=true;

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