From: Martijn Tonies
Date: February 11 2010 5:27pm
Subject: Re: how things get messed up
List-Archive: http://lists.mysql.com/mysql/220666
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>>  I think store files in DB has no complicated reasons, just for
>>convenience. For example, I might make files automatically be
>>backup-ed, and no budget for an independent backup solution. Thanks.
>>  Cui
>>
> [JS] Storing BLOBs in a table must slow down the inner workings of the
> database engine. After all, the tables are really disk files under the 
> covers.
> Can the database engine read only parts of a file record?
>
> Jerry Schwartz

Well, there's where things go wrong -- first of all, a "database engine"
can do -anything- it likes with the actual data.

For example, the Firebird DBMS stores (longer) Blob data not right
there in the record, so whenever you don't request the blob (that is,
not selecting it), it ignores it completely and it can go through the file
quickly.

If BLOB data makes the DBMS slowish by default, it's an implementation
issue that needs to be fixed.

Conceptually, there's much to say -for- storing binary data in database 
tables,
see the post by Joerg for example.

With regards,

Martijn Tonies
Upscene Productions
http://www.upscene.com

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