on 30/3/01 19:13, Oreste Tommasi at tommasi .AT. infmedia .D.O.T sns.it wrote:
>>> Another question about space on disk: our single binary item can be variable
>>> in size from 4 B to hundreds of kB; statistically, we have many short binary
>>> items and few big items. For us the size of database files is important: if
>>> we
>>> use a BLOB field with short binary items, which will be the occupation on
>>> disk? It si comparable with that of a VarChar field (+4 B for the BLOB
>>> pointer), or it is strongly affected by the BLOB segment size?
>>
>> If MOST of values are close to 4-5-6KB and only sometimes you get big item,
>> then best choice is about 6-6.5 KB
>>
>> In this case if you have item 60KB then it will use say 10 segments and you
>> get overhead 32 * 10 = 320 bytes.
>>
>> 320 bytes / 60 KB = 0.5%
>
> Most of our binary items are very short (10-20 B), so even a 128 B segment
> would be to long. Is there the possibility of having BSOB (Binary Small
> OBjects) or a VarBinary with an occupation similar to VarChars? Otherwise we
> have to implement a structured grouping/ungrouping procedure among related
> items (they can be logically grouped, with an average group size of 30
> items).
If you have so different by size items then it is good to use 2-3 different
fields with different segment size.
For 10-20 bytes items of course ideal is VarChar field.
but problem that you using V4MD ...
From other products you'd could do that.
I am going to add VarBinary, but not so fast.
what is your time line?
I hope to hear in answer 1-3 months :-)
> To give you an idea, we have 10 M of items, in a table with 3 fields (long,
> long, VarBinary), with an average size per record of about 25 B; everything
> must fit on a CD-ROM, so we must find a solution close to the physical size of
> the whole data set.
--
Best regards,
Ruslan Zasukhin
-------------------------
Paradigma.
e-mail: ruslan@paradigmasoft.com
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