Expert Oracle Exadata - Parent Directory

CHAPTER 5 EXADATA SMART FLASH CACHEFlash Cache Writes - I / O Path ArchitectureWrite Operation3DBAcknowledgement1cellsrv2 4DBCacheFigure 5-3. Conceptual model of write operation I/O pathAs you might guess, Smart Scans generally ignore the ESFC and read directly from disk. However, ifthe object being scanned has been designated for preferential caching (by setting the storage clauseattribute CELL_FLASH_CACHE to KEEP), then even Smart Scans will attempt to read from flash cache. Thefollowing example demonstrates this behavior.SYS@EXDB1> @mystatsEnter value for name: cell flash%NAMEVALUE---------------------------------------------------------- ---------------cell flash cache read hits 3570Elapsed: 00:00:00.01SYS@EXDB1> alter table kso.skew3 storage (cell_flash_cache keep);Table altered.Elapsed: 00:00:00.01SYS@EXDB1> select avg(pk_col) from kso.skew3 where col1 > 1;AVG(PK_COL)-----------16053318.5130