Oracle Exadata Survival Guide by David Fitzjarrell & Mary Mikell Spence

Author:David Fitzjarrell & Mary Mikell Spence
Language: eng
Format: epub
ISBN: 9781430260103
Publisher: Apress

Performance Counters and Metrics

The V$SQL and GV$SQL views provide two metrics we have used to prove Smart Scan execution, io_cell_offload_eligible_bytes, and io_cell_offload_returned_bytes. These are used to compute the percentage of data not read because a Smart Scan was executed. We provided this script in Chapter 2, but it is good to look at it again and understand what it reports:

SQL> select sql_id,

2 io_cell_offload_eligible_bytes qualifying,

3 io_cell_offload_eligible_bytes - io_cell_offload_returned_bytes actual,

4 round(((io_cell_offload_eligible_bytes - io_cell_offload_returned_bytes)/io_cell_offload_eligible_bytes)*100, 2) io_saved_pct,

5 sql_text

6 from v$sql

7 where io_cell_offload_returned_bytes> 0

8 and instr(sql_text, 'emp') > 0

9 and parsing_schema_name = 'BING';

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