Subject Re: [firebird-support] BLOB performance
Author Ann W. Harrison
yuraukar wrote:
> Similar to my varchar question: I am concerned about BLOB performance.

Don't be. It's OK.

> Someone indicated that tables having a BLOB field perform slower. In
> fact, the statement was that the whole DB would/could perform slower
> if using a single fdb/gdb file.

Someone was wrong. That happens.

> Is that true? Would I be better off moving the BLOB field into a
> separate table or even file?

No. Blobs are not part of the record, but are stored on data pages in
the database. When you retrieve the record, the "normal" fields you
request are returned. If you include the blob field, you get a number
that tells the system where to find the blob. You then go back and get
the blob if it exists. So blobs don't slow down "normal" fields. Going
back to get the blob is cheaper than opening a second table - let alone
opening a second file.

> I have the situation where a table has some "normal" columns which
> will always be filled and only in some rare situations, additional
> BLOB data will need to be attached. What would be the best design here?

Use a blob field in the relevant record.