====== Oracle Performance & Tuning ======

===== PGA & SGA =====

**Check current PGA and SGA :**
<sxh sql>
show parameter sga;
show parameter pga;
</sxh>

===== Sessions & Connections =====

**Show current and maximum sessions :**
<sxh sql>
SELECT
  'Currently, ' 
  || (SELECT COUNT(*) FROM V$SESSION)
  || ' out of ' 
  || VP.VALUE 
  || ' connections are used.' AS USAGE_MESSAGE
FROM 
  V$PARAMETER VP
WHERE VP.NAME = 'sessions';
</sxh>

===== AWR =====
**AWR Retention period :**
<sxh sql>
select snap_interval, retention from dba_hist_wr_control;
</sxh>

=====Bloom Filters=====
https://www.doag.org/formes/pubfiles/8319505/BloomFilters20160812.pdf