Re: B-Tree and oracle question...maybe a tough question

Thanks for the information. You gave me a some good information...

"mark" <mark_brehmen_at_yahoo.com> wrote in message news:fa4781e4.0108142022.59c4c4fa_at_posting.google.com...
> << I understand, Oracle uses b-tree to insert records on indexed
> fields>>
> Oracle does not use the basic B tree for index retrieval. It uses a
> modified version of it.
>
> <<would there
> not be a time where it will basically take the same amount of time to
> insert
> a record regardless of the number of existing records in the table>>
>
> No, assuming no deletions, more records you put into the table, more
> the time it takes for index retrieval. The height of the B Tree index
> increases as you put in more records. Again if it is a low cardinality
> column, index performace degrades if you put in more rows as the index
> becomes skewed.
>
>
> <<
> Is there an algorytmn that I can use to
> calculate the time it will take to insert a record given a number of
> records
> that are currently in the database...for example...on the average how
> long
> will it take to insert a record in a table that contains
> 1,000,000,000
> indexed records>>>>
>
> No ,But i have come across algorithms which tells me the number of
> I/O needed
> for index retrieval. It may be likely that you will get one for
> insertion. But these algorithms require complex mathematics and are
> difficult to use. Again you may not be able to convert the number of
> I/O needed into actual time . So best idea is to forget it. Also these
> algorithms are available for generic B trees and not for Oracle's
> version of it !. As far as i know Oracle, nor any other company has
> released such algorithms. Its top secret and i remember one professor
> in some paper saying that earlier many database vendors did not
> release even the basic details of how it works !.
>
> In other words its not possible to do what you are asking.
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> "DCCoolBreeze" <aa_at_bb.net> wrote in message
 news:<9l9snq$5nl$1_at_bob.news.rcn.net>...
> > I have an unusual question. As . Given my rudimentary understanding
 of B-Tree, would there
> > not be a time where it will basically take the same amount of time to
 insert
> > a record regardless of the number of existing records in the table?
> >
> > I will actually be working with a billion records so I want to know how
 long
> > it will take to insert a record into a table with this number of indexed
> > records. I know that I could load that number of records and time the
> > inserts but I currently do not have the facilities to do this...
> >
> > Any help???
Received on Wed Aug 15 2001 - 22:04:55 CEST