Db's segment size

[Ivan Smahin]

On Mar 11, 2012, at 2:11 PM, Ivan Smahin wrote:

> 
> On Mar 11, 2012, at 1:29 PM, Beatrix Willius wrote:
> 
>> Hi Ivan,
>> 
>> some questions:
>> 
>> - what is the default size of the segment file?
> 
> 32KB
> 
>> - are there other drawbacks when using a bigger segment size?
> 
> Assume your data is about 1MB only, but you choose 10MB as db's segment size - so you will get approximately 20MB ( first segment for service internal data + second segment for user data) for each volume (in case of 4 dedicated volumes it will be 80MB, in case of a single volume it will be 20MB ...) and all of these just for storing your 10MB data.

Mistyping - your 1 MB data.

> 
> Another point is - assume your data is slightly bigger then a single segment size. Even if it is 1 byte bigger, the next segment will be allocated (10MB) to store that additional 1 byte.
> 
> 
> 
>> - what happens if you hit the max number of segments?
> 
> You should get an error, but this area is very complex, complicated, with lot of optimizations. You'd better stay away from this situation. And finally you'll get no options besides migration data to the new db with dumps.
> 
>> - why do I need to manage this manually?
>> 
> 
> Default segment size lets you have a db up to 64GB. It is hard to say how much is it - obviously it depends on db nature. But in average, it seems to be a good compromise between a "db chunk size" (32KB is not so much to spare even to keep that additional single byte) and "growing capabilities".
> 
> But if you plan to keep some genome data or lot of pictures, documents and so on, then, probably 64GB limit is too low - so you should choose bigger segment size.
> 
> 
>> On 11.03.2012, at 11:21, Ivan Smahin wrote:
>> 
>>> There is a short note about choosing appropriate db's segment size.
>>> 
>>> http://www.valentina-db.com/blog/?p=852
>> 
>> Mit freundlichen Grüßen/Regards
>> 
>> Trixi Willius
>> 
>> http://www.mothsoftware.com
>> Mail Archiver X: The email archiving solution for professionals
>> 
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> 
> -- 
> Best regards,
> Ivan Smahin
> Senior Software Engineer
> Paradigma Software, Inc
> Valentina - The Ultra-Fast Database
> http://www.valentina-db.com
> 
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-- 
Best regards,
Ivan Smahin
Senior Software Engineer
Paradigma Software, Inc
Valentina - The Ultra-Fast Database
http://www.valentina-db.com

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