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Tuning: overview Rewrite SQL ( Leccotech ) Create Index Redefine Main memory tructure (S!" in #rac$e) Change the %$oc& Si'e

Materia$i'ed iew *enorma$i'ation +x,ort-Im,ort (dro, indexe ): defragment Chec& Loc& Se,arate data .y category in ,ro,er ta.$e ,ace /artition *ata.a e Redundant "rray of Inex,en ive *i & (R"I*) Redefining C$ient0Server "rchitecture

%uy 1ardware

http://www.orafaq.com/tools/leccotech/sqlexpert.htmhttp://www.orafaq.com/tools/leccotech/sqlexpert.htm

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*ifferent Ty,e of Indexe

%0Tree (traditiona$) indexe 1a h0c$u ter %itma, indexe Index0#rgani'ed Ta.$e

Rever e07ey Indexe

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Create Index command

Create index 8i9ame on8tname (8co$;name )t &now what to do the .e to,tion i u ua$$y a %0Tree5 They are f$exi.$e

and ,erform we$$ (not very we$$) in evera$cenario 5 It i rea$$y the %? tree or %@ tree

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%0Tree (continued) #ne node corre ,ond to one .$oc&-,age

(minimum di & I0#)5

9on0Leaf node (n &ey n?A ,ointer ) Leaf09ode (contain n entrie where each

entry ha an index and a ,ointer to a data

.$oc&)5 "$ o each node ha a ,ointer tonext node5

"$$ $eave are at the ame height5

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!ood Indexing (%0Tree)

Candidate Ta.$e mu t .e rea ona.$y $arge 4ie$d i 3ueried .y fre3uent$y 4ie$d ha a high cardina$ity (don>t index .y

ex where the cardina$ity i 6BB)5 %ad$y .a$anced tree may inhi.it

,erformance5 *e troying and re0creatingindex may im,rove ,erformance5

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%itma, Index

%itma, indexe contain the &ey va$ue and a .itma, $i ting the va$ue of or A (ye -no)

for each row indicating whether the rowcontain that va$ue or not5

May .e a good o,tion for indexing fie$dthat have $ow cardina$ity (o,,o ite of %0tree )5

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%itma, Index (cont5)

Syntax: Create Bitmap index . %itma, index wor& .etter with e3ua$ity te t = or

in (not with < or > ) %itma, index maintenance can .e ex,en ive< an

individua$ .it may not .e $oc&ed< a ing$e u,date$oc& a $arge ,ortion of index5

%itma, indexe are .e t in read0on$ydatawarehou e ituation

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1a h Indexing

%0tree and %itma, index &ey are u ed tofind row re3uiring I-# to ,roce index

1a h get row with a &ey .a ed a$gorithm Row are tored .a ed on a ha hed va$ue Index i'e hou$d .e &nown at index

creation +xam,$e:

D create index cidx on order (cid) ha hed