query optimization(tối ưu hóa câu truy vấn trong csdl)

Query Optimizer
Các K Thu t Liên Quanỹ ậ
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
 !"#"!$%
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& '()("
 *+ ",""$-./0
1%
Các K Thu t Liên Quanỹ ậ
1. CURSOR_SHARING
2. DB_FILE_MULTIBLOCK_READ_COUNT
3. OPTIMIZER_INDEX_CACHING
4. OPTIMIZER_INDEX_COST_ADJ
5. OPTIMIZER_MODE
6. PGA_AGGREGATE_TARGET
7. STAR_TRANSFORMATION_ENABLED
1 CURSOR_SHARING
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2"3  #45#6"./0#7" 78%
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&"3  #4,!9#:;"###<,88
1 6"./0%
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2"#811#1- 78#7"!'
(, #418=4=
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&>?.@.A.BC?DEFG 456"./09HI#:%
1 CURSOR_SHARING
Thuộc Tính Miêu tả
J" .#

&K( ( &>?.@?A.BC?DEFLM.DND0C?OPQC&2OR@?&PS
F #4T4 PQC&2
.3 C02P?.P D@EUC02P?.V.2PN
&>?.@?A.BC?DEFG 456"./09H#:%

R@?&PW& "I5U#X 5,8YZ%

.DND0C?W& "I5U#X 5,8YZT7[ 8"%

PQC&2W&\()(7  !]!+7,"9H#:%
2 D B_F I L E _MU L T IB L OC K _ R EA D _ C OU N T
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0# '7,"D^@#_" #`_")
7,%/"4- a#D^@#_")
"1%23D^@817,-_")("! 8"
b]-7,U"c7a8U!H1
%
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@#=d7=Ie#===fU #4T4- #4gh!]D^@
b]1 "_",%F #4("!i,!
INj(k#%j="="8 # Ul8m(
 #4gg!]b]D^@1"_",Ub
]c""n%0"Y#[8"-(a(!'H]"c7a #4
,# 7]=74#m(!]7_")_" i"7,%
2 D B_F I L E _MU L T IB L OC K _ R EA D _ C OU N T
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NTH #4T4 #4]U'"l'-8]8"7
'T%El!m8"7#o#8m(8 #4
]%
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QY4#1"8;@02<!'#pp #4#(!-q8
Ir%d !'#p5"G"]i"$X 
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8" #4-%
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F #4]$b]-i"D^@ @#=;;D^@
b]<^djAj0@&JA.DsP<%E8"78m( #4]ghU
@#=%
2 D B_F I L E _MU L T IB L OC K _ R EA D _ C OU N T
Thuộc Tính Miêu tả
J" D==#
!-  #4 "!i"
F #4T4 F #4T4gh!]D^@b]
1"_",!("!i,
.3 C02P?.P D@EUC02P?.V.2PN
3 OPTIMIZER_INDEX_CACHING

@2DNDsP?ADEdPQA&C&BDEF()(7i"(b1#" !t
T(u"!DEv!tT(%

&(b1\7[ !tT(DEvT1!tT(
u"\#"m(!7,7#("!
7]-\#7]=

.7]("! 8"'"'1 Uw
,#!'`#"m(-pH "%
3 OPTIMIZER_INDEX_CACHING

j3 ,4-"!i7]\ !tT(u"
!!tT(# 7[ 8m(8 #4Xe8

Iee\#x(#+- \",4#7]=%

28m(8 #4g!tT(u"!DEv
 !tT(G=b)'"%

J8_",Uli",+a!tT(u"#7+Ty(G8(U
($!a \DEv !tT(# \ T
_")77,%NT4eU8_",#!"T4%
3 OPTIMIZER_INDEX_CACHING
Thuộc Tính Miêu tả
J" D==#
!-  #4 evIee
F #4T4 e
.3 C02P?.P D@EUC02P?.V.2PN
4
OPTIMIZER_INDEX_COST_ADJ

@2DNDsP?ADEdPQA&@.2ACdz=""=(c{=#7=!#|#=(==c7=
#=#==G|#=}U==(c{=##=#=(#===c
=G=(!=#|"7=%

2==|"|#(#==#Iee(=#=U~=(c{=#=!"==G=(
=#="#%C=#!"===(c{=#=!"===(
(=#==|=#="#%R#=G(=U=•|€e===G=(|
=G(=!=#%

Note:2=•"==(("=#v=‚=|"c|#=G=%
4
OPTIMIZER_INDEX_COST_ADJ
Thuộc Tính Miêu tả

J" D==#
!-  #4 evIeeee
F #4T4 Iee
.3 C02P?.P D@EUC02P?.V.2PN
5 OPTIMIZER_MODE

@2DNDsP?AN@dP=7===|"7=!#|#(c{c((#|#=
=%

Values:

‚#A#~An : 2=(c{=#"=v7=((#(c{=~|7=
#=(=c=#="#=‚#n#~;~=#=nLIUIeUIeeUIeee<%

‚#A#~W2=(c{=#"=G|="#c‚7=(|#|=!=#|
=‚#|=~#~%

A#~W2=(c{=#"=v7=((#|#./0====
(c{=~|7=#"(";"#="#="=(====c#===<%
5 OPTIMIZER_MODE
Thuộc Tính Miêu tả
J" .#
&K ( @2DNDsP?AN@dPLM‚#A#~AƒIOIeOIeeOIeee„O
‚#A#~OA#~S
F #4T4 C00A?@….
.3 C02P?.P D@EUC02P?.V.2PN
6 PGA_AGGREGATE_TARGET

FCACFF?PFC2PA2C?FP2(=‚==#=#==FC=#!7==#!=#
(#==†===%


.=•FCACFF?PFC2PA2C?FP2{=#!"===‡=|"c=•
=…@?JC?PCA.DsPA@0D&V(#==#C>2@%2=./0~##="=7
=#v=!=./0(=##;"#U#"(v7Uv•U7(=#=U7(
#==<~7="c{=%C{=#!"=|#(#==#==|"=U"=
"(=|=#~=U@#==feˆ|=.FC#IeNjU~=!=##==#%
6 PGA_AGGREGATE_TARGET

.=•FCACFF?PFC2PA2C?FP2e"c==…@?JC?PCA.DsPA@0D&V(#==#
NCE>C0%2=./0~##=#={="=‰AC?PCA.DsP(#==#%

@#=†=(==(="|(#!==#7=~=#=(=‚=7
(#==#7(c={=|=~##=(#!==#%…=#==!"=
|(#==#U"#=#====#†=~##=%&=_"=U#=
=#v=!=(=#c#=7=#"|"=#=~~#=#~!=#
%
6 PGA_AGGREGATE_TARGET

…==•(#==#U""=G===#"#=
!7==@#=="7#=.FC%V"=#==#
FCACFF?PFC2PA2C?FP2%
6 PGA_AGGREGATE_TARGET
Thuộc Tính Miêu tả
J" j==#
&K ( FCACFF?PFC2PA2C?FP2LintegerƒJONOF„
F #4T4 IeNj#feˆ|={=|=.FCU~=!=##==#
.3 C02P?.V.2PN
!-  #4 N"WIeNjNG"WqeŠrFjvI
&g7, V=
7 STAR_TRANSFO RMA TION_ENABLED


.2C?A2?CE.R@?NC2D@EAPECj0Pd==#=~==#v7=_"=##|#c~
7=((=#_"=#=%

Values:

2?>PW2=(c{=#~=#(=#|#v7=_"=##|#c=#_"=#%

RC0.PW2=#|#c~7=((=%

2PNAdD.Cj0PW2=(c{=#~=#(=#|#v7=_"=##|#c=
#_"=#7"~"==(##7==##|#c%
7 STAR_TRANSFO RMA TION_ENABLED
Thuộc Tính Miêu tả
J" .#
&K ( .2C?A2?CE.R@?NC2D@EAPECj0PdLM2PNAdD.Cj0PO2?>P
ORC0.PS
F #4T4 R=
.3 C02P?.P D@EUC02P?.V.2PN
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