Re: size of index

Not exacly.
You must add :

• Rowid (for each row)
• Block header, column directory, transaction entry etc. (for each block)
• Pctfree (for each block) The size of varchar2 dataype is variable. For calculation, considere the average column length : select avg(vsize(col1)) .....

A good idea is to have a look on Oracle manuals. Oracle (7 or 8) Administrators Guide : estimating space for indexes

karsten reincke a écrit dans le message <376DED80.89B4B912_at_cl-ki.uni-osnabrueck.de>...
>hello;
>
>(1) does exist any rule for computing the necessary size of an index?
>
>we will have a table of more than 4 Million rows, each row containing
>more that 3K. and we want to create an index for two columns of that
>table, both being of type VARCHAR(40). what is the method for computing
>the size ofn that index?
>
>(2) is this a good rule for computing the size of an index:
>
>( (size of columntype) [+ (size of columntype) ...] ) * expected number
>of rows )
>
>in our example:
>
>[ 40 B + 40 B ] * 4000000 = 320 MB
>
>
>many thanks for your comments and/or your hints?
>
>--
> salut d'Allemagne kr
>-----------------------------------
>les chats cont les vrais hédonistes
>et devraient être donc notre idéal.
>-----------------------------------
> karsten reincke [ 0541/9696223 ]
> kreincke_at_cl-ki.uni-osnabrueck.de
Received on Mon Jun 21 1999 - 07:49:26 CDT