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Re: types used for JDBC BLOB and CLOB?

From: "Marc G(dot) Fournier" <scrappy(at)postgresql(dot)org>
To: David Wall <d(dot)wall(at)computer(dot)org>
Cc: pgsql-jdbc(at)postgresql(dot)org
Subject: Re: types used for JDBC BLOB and CLOB?
Date: 2004-08-24 02:05:38
Message-ID: 20040823230510.M4215@ganymede.hub.org (view raw or flat)
Thread:
Lists: pgsql-jdbc
Perfect, thank you ... re: the lo_ calls ... ya, I figured that, but I 
needed something to act as a reference for this ;)

Thanks ...

On Mon, 23 Aug 2004, David Wall wrote:

> If you want to use the BLOB JDBC calls, you will use the OID type for the
> field in your table schema.
>
> You do NOT need to use the lo_ routines since they will be called for you if
> you use the JDBC BLOB calls.
>
> David
>
> ----- Original Message -----
> From: "Marc G. Fournier" <scrappy(at)postgresql(dot)org>
> To: "Barry Lind" <blind(at)xythos(dot)com>
> Cc: "Marc G. Fournier" <scrappy(at)postgresql(dot)org>; <pgsql-jdbc(at)postgresql(dot)org>
> Sent: Monday, August 23, 2004 3:06 PM
> Subject: Re: [JDBC] types used for JDBC BLOB and CLOB?
>
>
>>
>> k .. I'm obviously missing something, and having never used BLOBs before,
>> I'm not surprised ...
>>
>> Looking at:
>>
>>   http://www.postgresql.org/docs/7.4/static/lo-implementation.html
>>
>> It states:
>>
>> "The large object implementation breaks large objects up into "chunks" and
>> stores the chunks in rows in the database."
>>
>> When I create my schema for this, what type do I assign the field?  Or is
>> there a special 'table' created when you do the lo_creat to store the
>> BLOBs in? (looking at docs, which references the libpq library vs JDBC,
>> sorry)
>>
>> For instance, I notice in:
>>
>>   http://www.postgresql.org/docs/7.4/static/lo-interfaces.html
>>
>> "Oid lo_creat(PGconn *conn, int mode);"
>>
>>    So, lo_creat returns an OID ... is that what I'd store in a table, and
>> when I needed the value, would call lo_open to actually access it as I
>> need?
>>
>>    The part that is confusing me is the point about 'chunks' above ...
> from
>> that, it seems that the data is stored in table within the database ...
>> but if so, what type does one define to store it in?  how would a
>> 'pg_dump' show the schema?
>>
>>    Hopefully this explains a bit better my confusion here :(
>>
>>
>> On Mon, 23 Aug 2004, Barry Lind wrote:
>>
>>> Marc,
>>>
>>> The answer is it depends, but if they intend to use the jdbc BLOB/CLOB
>>> interface it is server side LargeObjects, not bytea.  However you can
>>> use bytea, but then you need to use the get/setXXXStream() interfaces.
>>>
>>> Thanks,
>>> --Barry
>>>
>>> -----Original Message-----
>>> From: Marc G. Fournier [mailto:scrappy(at)postgresql(dot)org]
>>> Sent: Monday, August 23, 2004 11:52 AM
>>> To: Barry Lind
>>> Cc: Marc G. Fournier; pgsql-jdbc(at)postgresql(dot)org
>>> Subject: RE: [JDBC] types used for JDBC BLOB and CLOB?
>>>
>>>
>>> 'k, I believe what the client is wanting to know is what the storage
>>> type would be on the backend, that the would BLOB/CLOB map to ... bytea?
>>>
>>> On Mon, 23 Aug 2004, Barry Lind wrote:
>>>
>>>> Marc,
>>>>
>>>> If you are specifically talking about the JDBC types BLOB and CLOB
>>>> those classes use the server LargeObject interface.  If you are
>>>> speaking generically about support for large objects then the jdbc
>>>> driver supports the bytea datatype for the get/setBinaryStream()
>>>> methods.  So the answer is "it depends", on how you use the driver.
>>>> The specifics for supporting binary objects are documented in a
>>>> section on this topic in the postgresql jdbc driver documentation
>>> chapter.
>>>>
>>>> Thanks,
>>>> --Barry
>>>>
>>>> -----Original Message-----
>>>> From: Marc G. Fournier [mailto:scrappy(at)postgresql(dot)org]
>>>> Sent: Monday, August 23, 2004 8:44 AM
>>>> To: pgsql-jdbc(at)postgresql(dot)org
>>>> Subject: [JDBC] types used for JDBC BLOB and CLOB?
>>>>
>>>>
>>>> Just been asked this, and I'm not sure of the answer ... based on
>>>> reading the docs on bytea, I'm assuming that it is such, but can
>>>> someone please confirm?
>>>>
>>>> Thanks ...
>>>>
>>>> ----
>>>> Marc G. Fournier           Hub.Org Networking Services
>>>> (http://www.hub.org)
>>>> Email: scrappy(at)hub(dot)org           Yahoo!: yscrappy              ICQ:
>>>> 7615664
>>>>
>>>> ---------------------------(end of
>>>> broadcast)---------------------------
>>>> TIP 7: don't forget to increase your free space map settings
>>>>
>>>>
>>>
>>> ----
>>> Marc G. Fournier           Hub.Org Networking Services
>>> (http://www.hub.org)
>>> Email: scrappy(at)hub(dot)org           Yahoo!: yscrappy              ICQ:
>>> 7615664
>>>
>>>
>>
>> ----
>> Marc G. Fournier           Hub.Org Networking Services
> (http://www.hub.org)
>> Email: scrappy(at)hub(dot)org           Yahoo!: yscrappy              ICQ:
> 7615664
>>
>> ---------------------------(end of broadcast)---------------------------
>> TIP 4: Don't 'kill -9' the postmaster
>
>

----
Marc G. Fournier           Hub.Org Networking Services (http://www.hub.org)
Email: scrappy(at)hub(dot)org           Yahoo!: yscrappy              ICQ: 7615664

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Subject: Re: types used for JDBC BLOB and CLOB?
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