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From TomohitoNakayama <tomon...@basil.ocn.ne.jp>
Subject Re: [jira] Updated: (DERBY-721) State of InputStream retrieved from resultset is not clean , if there exists previous InputStream .
Date Tue, 06 Dec 2005 12:13:42 GMT
<monologue>
Restriction of "each row should be read in left-to-right order, and each
column should be read only once" in java.sql.ResultSet would have
some impact on Streaming between client and server , because DRDA seems
to stream LOB between client and server only once and in left-to right
order as in sql ....
</monologue>

TomohitoNakayama wrote:

> Hello Daniel and Mike .
>
> Do you think it is preferable not to allow user to call getXXXXStream
> twice from one row ,
> in order to make a room for releasing memory for cache in ResultSet as
> soon as possible ?
>
> Best regards.
>
>
> Daniel John Debrunner wrote:
>
>> Mike Matrigali wrote:
>>
>>
>>
>>> Is there anything in the standard that says what the second call to
>>> the get the stream has to do? Imagine the case where the first
>>> stream reads 1 gig of a 2 gig blob, does the second call to
>>> getBinaryStream() have to return the 1st gig again?
>>>
>>
>> Yes & no.
>>
>> Nothing in the JDBC spec doc, but the javadoc for java.sql.ResultSet has
>> always had:
>>
>> " For maximum portability, result set columns within each row should be
>> read in left-to-right order, and each column should be read only once."
>>
>> Thus, Derby could thrown an exception if there was a second getXXXStream
>> call on the same column.
>>
>>
>>
>>> Any change that tries to cache the bytes returned by the first
>>> getBinaryStream either in local client or network client code is
>>> going to be a performance/memory drain.
>>>
>>
>> Agreed, we need to be careful here, we need to optmise the frequent
>> case, getting the column's value once as-per JDBC.
>>
>> Dan.
>>
>>
>>
>>
>>
>>
>

-- 
/*

        Tomohito Nakayama
        tomonaka@basil.ocn.ne.jp
        tomohito@rose.zero.ad.jp
        tmnk@apache.org

        Naka
        http://www5.ocn.ne.jp/~tomohito/TopPage.html

*/ 


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