AFAIK, the "Segment Size" no longer has any effect in most circumstances.

And, as each blob access requires it's own read operation, you effectively
double the database traffic to retrieve the records.

You would be far better off using a sufficiently large varchar, but you'll
lose the ability to store unexpectedly long values.

A compromise would be, it the value is less than 1000 characters, use the
varchar, otherwise, store it in the BLOB. This will give you speed for most
retrieve operations, and the ability to store massive values if needed.


Nige.

-----Original Message-----
From: firebird-support@yahoogroups.com
[mailto:firebird-support@yahoogroups.com]On Behalf Of Christian Kaufmann
Sent: Friday, 30 June 2006 5:45 PM
To: Firebird Newsgroup
Subject: [firebird-support] Blob fields


Hi,

I have some performance problems with an application, where I store
geometries in blob fields. Reading 12'000 records takes very long and
I'm looking, how to speed it up. The technology we use is:

- Delphi 6
- dbExpress, driver from upscene.com
- Firebird 1.5, server Win32

One thing is, that most of the blob fields data has a size of 100-1000
bytes. So my question is, what exactly does the "SEGMENT SIZE" in the
declaration of the blob field? Should I change that to another value
than the default of 80?

Will Firebird 2.0 be different regarding blob fields and performance?

cu Christian




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