Re: create BLOB question - Mailing list pgsql-jdbc

Jeremiah,

 From the jdbc documentation:

PostgreSQL provides two distinct ways to store binary data. Binary data
can be stored in a table using PostgreSQL's binary data type bytea, or
by using the Large Object  feature which stores the binary data in a
separate table in a special format, and refers to that table by storing
a value of type OID in your table.

In order to determine which method is appropriate you need to understand
the limitations of each method. The bytea data type is not well suited
for storing very large amounts of binary data. While a column of type
bytea can hold up to 1 GB of binary data, it would require a huge amount
of memory (RAM) to process such a large value. The Large Object method
for storing binary data is better suited to storing very large values,
but it has its own limitations. Specifically deleting a row that
contains a Large Object does not delete the Large Object. Deleting the
Large Object is a separate operation that needs to be performed. Large
Objects also have some security issues since anyone connected to the
database can view and/or modify any Large Object, even if they don't
have permissions to view/update the row containing the Large Object.

7.2 is the first release of the JDBC Driver that supports the bytea data
type. The introduction of this functionality in 7.2 has introduced a
change in behavior as compared to previous releases. In 7.2 the methods
getBytes(), setBytes(), getBinaryStream(), and setBinaryStream() operate
on the bytea data type. In 7.1 these methods operated on the OID data
type associated with Large Objects. It is possible to revert the driver
back to the old 7.1 behavior by setting the compatible property on the
Connection to a value of 7.1

To use the bytea data type you should simply use the getBytes(),
setBytes(), getBinaryStream(), or setBinaryStream() methods.

To use the Large Object functionality you can use either the LargeObject
API provided by the PostgreSQL JDBC Driver, or by using the getBLOB()
and setBLOB() methods.





Some of the formatting was lost in the cut-n-paste of this from the doc,
but in summary if you add '?compatible=7.1' to your connection URL you
will get the old behavior.

thanks,
--Barry




Jeremiah Jahn wrote:
> does some9one out there know how to create a new oid from scratch.
> setBytes on 7.2 worked fine for me, but with the change to 7.3 I can't
> seem to get a new oid number. I want to avoid any postgres specific
> stuff. Correct me if I'm wrong, but It seems to me that the setBytes
> goes with the bytea stuff and the BLOB stuff goes with the oid stuff. I
> just can't seem to figure out how to insert a new oid/BLOB.
>
> any help would be great,
> thanx
> -jj-