Po povodu :
>>> 2) DBWR Average Scan Depth - 800,0000 (number of DB_FILES too high?)

Na moy vzglyad vivod "number of DB_FILES too high" ne vpolne korrekten.
Oracle vichislyaet srednuyu dlinnu skanirovaniya v db cache po formule
(NOTE!!! esli ispolzuetsya tolko DEFAUL db cache)

l_avg = min ((db_files * _db_file_simutanious_write)/2 , db_block_buffers/4)

no db_files --> ne tekuschee kolichestvo a to chto zadano v CREATE DATABASE kak MAXDATAFILES (ili v create controlfile)
parametr _db_file_simutanious_write v poslednih versiyah - undocumented i ego luche ne trogat

t.e. esly v control file pri sozdanii database zadano bolshe chem nuzno, kak by pro zapas,
eto potencialno mozet uvelichit dlinu skanirovaniya LRU do 1/4 db buffers v cache

V etoy situacii u meniy vopros:

kak ustanovleny parametry --> DB_BLOCK_SYZE, DB_BLOCK_BUFFERS
t.k 800,0000 smotritsia kak nepomerno bolsaya velichina. i mne ne veritsya v eto t.k -->
avg len = MIN(db_block_buffers/4) esly MAXDATAFILES ochen veliko

Po povodu :
>>> 1) Parse to execute ration - 29.2
Eto ne kolichestvo razborov a HIT RATIO, t.e. Sootnoshenie kolichestva razborov k kolichestvu vipolneniy
znachit 29% sql statments prohodiyat fazu razbora a ostalinie prosto otpravliautsya na vipolnednie.

1) 3200 --> eto vesma malo dlya production (i ogranicheniy dlya 8.0.5 net)
I vistavlyu ~ 50000-70000 pri db block = 4K i memory ~ 1 GB (mogno i bolshe)
i eto est prichina DBWR Average Scan Depth - 800,0000 (oracle vinugden chasto iskat
free block - a ih net t.k. cache malenkiy => nugno pisat dirty blocks na disk => nugno skanirovt ocheredy) otsuda i ogromnoe kolichestvo scanirovaniy dlya zapisi
-- NOTE!! znacit TOAD schitaet ne dlinu skanirovaniya a prosto ih kolichesvo --> neporyadok

2) o 29% --> kak pravilo prichina v neprimenenii (ili ogranichennom primenenii bind peremennih)
v bolshenstve situaciy bez pererabotki koda prilogeniya nichego ne sdelat

pravda est paramater CURSOR_SHARING = FORCE no esly ego ispolzovat to nado bit uverennim
v dostatochnom razmere SHARED POOL (a tochnee v library cache)
CURSOR_SHARING = FORCE mozet nescolko snizit kolichestvo razborov z schet generacii
PSEVDO imen PSEVDO bind peremennih