Database Size?

[Ruslan Zasukhin]

On 8/20/04 6:47 PM, "Brendan Murphy" <bmurf at comcast.net> wrote:

>> IF you have other case:
>>     initial db size was e.g. 0.5Mb, but it go to 18Mb,
>>     then probably you have wrong settings for BLOB/Text fields
> 
> Valentina 1.10 has the classic space vs speed characteristics. The
> bigger you make your segment size the faster it is at the cost of
> wasting a lot of disk space.

NO Brendan! Absolutely wrong understanding.

Valentina (as well as any other good DBMS) try compact data on disk as much
as possible!

Because disk I/o Is the most slow thing.

The EXTRA disk space, as I have explain, do not contain data.
So it not play in game until it get own data.
Valentina do not touch that ZEROed space.

But if you know that your data are big, and that empty space in any case
will be used, then it is better to pre-allocate it, to reduce overhead of
internal file system.


> The smaller you make your segments, the slower it will become, but file size
> will shrink dramatically.

Also not 100% correct.

For example if we set segment size to 4Kb then READ operation, will not be
affected....almost. May be few percents. But WRITE operations, and I'd say
BATCH WRITE when we add a lots of new records can be slower.


> The law of diminishing returns applies to the extreme ends of
> segement size.

> In one of my main projects I did an analysis of the space vs speed
> ratio and plotted them on a graph and then chose a segment size
> that was satisfactory to my particular situation (I found 8KB was
> the optimum size for me). If performance is critical to your
> application, I suggest taking the time to plot out the effects of
> changing the segment size so that you can achieve the right
> balance.

I think you see difference, only because Valentina 1.x have had not the best
algorithm for internal FAT.

Valentina 2.0 have new algorithm, which is 300-500 times faster.
So I think this difference will go away.

-- 
Best regards,
Ruslan Zasukhin      [ I feel the need...the need for speed ]
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e-mail: ruslan at paradigmasoft.com
web: http://www.paradigmasoft.com

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