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Date: Sun, 8 May 2005 12:46:52 -0700 (PDT)
From: Thomas Fischer <tfischer@apache.org>
To: torque-dev@db.apache.org
Subject: BLOB and CLOB Torque datatypes
Message-ID: <20050508122835.T95388@minotaur.apache.org>
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Hi,

I am pondering about which datatypes should be mapped to the Torque BLOB 
and CLOB types, and which should not. Background is that "real" Blob and 
CLOB data types are handled differently by the jdbc drivers than other 
types, in the sense that for a CLOB or BLOB column, one does not get the 
value directly, but a stream from which one can read (or into which one 
can write). So, in a sense, for "normal" datatypes, you get the 
value directly, for BLOB/CLOB, you get a reference. Torque hides this 
different behaviour from the user.

So I would suggest that we define a minimum length for which we assume 
that a column is a "large object". For the columns that I have in mind to 
change (Postgresql BYTEA-> Blob, HSQLDB LONGVARBINARY -> BLOB, HSQLDB 
LONGVARCHAR -> CLOB) these objects can be up to 2^32 bytes/characters 
long. But if a data type in a database meets this length criterium, we do 
not care whether it can be accessed in a blob-scpecific way or not, we 
just map the BLOB/CLOB Torque types to these values.

Any comments, objections etc ?

          Thomas

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