[yunqa.de] Re: Performance and DiSqlite database size?
- From: Edwin Yip <edwin.yip@xxxxxxxxxxxxxxxxxx>
- To: yunqa@xxxxxxxxxxxxx
- Date: Mon, 26 Oct 2009 00:36:18 +0800
Hi Ralf,
Thanks for the information. While the information is already very helpful,
I'd like to clarify my question, 100 MB is the estimated total size of the
blobs, for each record the blobs should be less than 1 MB usually, so I
think this can be can be handled in DISQLITE effectively according to your
information :)
One more question, I just checked the DISQLite3_Blob_and_Streams DEMO
program and noticed that the TDISQLite3IncrBlobStream.Create constructor
method needs a 'database name' parameter while a 'database connection' is
already supplied, I don't understand why a 'database name' is still needed
and how do I know the name? 'main' is passed in your demo, is this a fixed
value? Thanks again.
On Sun, Oct 25, 2009 at 10:30 PM, Delphi Inspiration <delphi@xxxxxxxx>wrote:
> At 12:37 25.10.2009, Edwin Yip wrote:
>
> >Does anybody has any real life experience about how the size a database
> affects the performance? Let's assume the database schema is well designed,
> and the size increase is mainly because of the large amount of data stored
> in the blob fields, say 100MB of blob data or so.
>
> I achieve good results with 8 GB database files with millions of
> small-sized blobs containing compressed text. I did not run tests with 100
> MB blobs, though. The SQLite developers do not recommend this. Instead, they
> suggest to store large BLOBs as disk files and reference them from within
> the DB. Research showed that databases are generally faster than
> file-systems for small BLOBs only (up to a few MB, IIRC).
>
> In any case, make sure you use the special SQLite BLOB API. Also know that
> you can speed up large database operations by giving more RAM to SQLite for
> page caching (the more, the better!).
>
> Ralf
>
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--
Best Regards,
Edwin Yip
Mind Mapping is as Effortless as Typing
http://www.InnovationGear.com
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