Hello.
Concerning about use of memory at driver,
I briefly surveyed client driver program to find where *whole of* object
was expanded into memory before sending it,
from code searched with keyword "writeScalarStream" as starting point of
survey.
The result was as next.
When org.apache.derby.client.am.Blob object was constructed with
parameter named binaryString typed as byte[],
whole of object is expanded into memory before the call of constructor.
But this seems not to be the scenario when InputStream was passed to
driver,
reading around setBinaryStreamX method in the
org.apache.derby.client.am.PreparedStatement class.
When org.apache.derby.client.am.Blob object was constructed with
parameter named binaryStream typed as InputStream,
it seems that whole of object was *not* expanded into continuous memory.
//Here, "continuous" means that it is true that the object is expanded
into *upper limited* memory array
//segmentedly at writeScalarStream method in
org.apache.derby.client.net.Request.
I'm not sure .....
My question is what was the stackTrace found in DERBY-550 ...
Does anyone have any information ?
I searched received mails in my mailbox , but could not found the
information of stackTrace ....
Now I found it not clear that the driver is writting all the file into
memory (RAM) before sending ...
Deeper survey may be needed yet ...
Best regards.
Bryan Pendleton wrote:
> Kristian Waagan commented on DERBY-1471:
> ----------------------------------------
>
> The approach is to exhaust the application stream and copy it into
> memory to determine the length. If the data is too big to fit in
memory,
> the client will fail with an out-of-memory exception.
That seems fine to me. This is already the case with the current
API and implementation, I believe, so we aren't making anything worse.
In practice, do application programs end up having *two* copies of the
BLOB/CLOB in client-side memory at the same time, one copy inside the
Derby
code and one copy in the application code? Or is there actually only a
single copy of the BLOB/CLOB in memory? I'm asking only because it seems
like we might want to be clear about this in our documentation.
thanks,
bryan
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