Re: RowSize Equation in Oracle ServerAdmin Guide for 7.3.4 and 8.0.#

I'am talking about syntax here!

"Rowsize=row header (3 * UB1)+ sum of column sizes"

-Should I read it like "Rowsize=row_header * (3*UB1)+sum..." or what? How do you read it?

-What kind of function is this
"Min(first_argument+all_arguments,another_argument)" Do you know any function min() with a comma in syntax???

>>Answer mixed in with extract from manual.
(give me a break)

J. Meirim

Jonathan Lewis wrote in message
<924890589.8085.1.nnrp-02.9e984b29_at_news.demon.co.uk>...
>Answer mixed in with extract from manual.
>
>--
>
>Jonathan Lewis
>Yet another Oracle-related web site: www.jlcomp.demon.co.uk
>
>Jorge Meirim wrote in message <7fq9oh$sqc$2_at_pthp35.telecom.pt>...
>>From the manual:
>>Step 3: Calculate the
>>Space Used per Row
>>=
>>column size + (1, if column size < 250, else 3)
>
>
>If column length is < 250 then add 1 for the 'length of column' variable,
>otherwise add 3.
>
>>Note: You can also determine column size empirically, by selecting
>>avg(vsize(colname)) for each column in the table.
>>Then, calculate the row size:
>>Rowsize
>>=
>>row header (3 * UB1) + sum of column sizes including length bytes
>
>
>The size of the row header is 3 x the length of type UB1, where UB1 is
>define in v$typesize (? v$type_size)- different platforms use different
>numbers of bytes to store different Oracle structures, a 'UB1' should
>be an 'unsigned single byte' but may actually be larger than one byte.
>
>
>>Finally, you can calculate the space used per row:
>>Space used per row (rowspace)
>>=
>>MIN(UB1 * 3 + UB4 + SB2, rowsize) + SB2
>>Where:
>>
>
>
>A row may actually need to become a row header plus a pointer
>to the migrated row, so Oracle reserves enough space in each
>block for this option irrespective of how small your row is. This
>minimum is:
> 3 'Unsigned single byte structures'
> 1 'Unsigned 4 byte structures'
> 1 'Signed 2 byte structure'
>
>And there is always a 'signed 2 byte structure' in the
>row index at the top/bottom of the block.
>
>
>PS - the biggest discrepancy in sizing comes on things
>like PCs, I think, where 'odd byte' structures are padded
>up to an even number of bytes.
>
>
>
>
Received on Fri Apr 23 1999 - 14:24:39 CDT