Is it possible to store Java objects in DB2 V8.2 for Windows/Unix/Linux via
JDBC?

Specifically, if I have a 4-dimensional boolean array, i.e. boolean[][][][],
can I store it directly in a column of a DB2 table? If so, how do I do it?

It would be VERY convenient if I could store this boolean array directly in
a column of a DB2 table but I'm not at all clear on whether this is
possible, even after reading the documentation in the Information Center. I
was intrigued by the setObject() and getObject() methods in JDBC but I'm not
at all sure if I can use them for the purpose I described. I'm especially
unlclear about what datatype the column containing the Object could/should
be.

If I can't store a multidimensional boolean array directly in a table
column, I can always convert it into a representation of the array that uses
more traditional datatypes. For instance, I could convert:

boolean[] myArray = {true, false, true};

into this String:

String myString = "TFT"; //T=true; F=false

then store the String representation of the array in one of the CHAR column
types. But it would be much more convenient if I could simply store the
boolean[][][][] array directly in a column of the table. Does anyone know if
that is possible? If it is, a brief code snippet showing how to insert the
value would be VERY helpful!

--
Rhino

It seems to be a programming strategy other than a database one. you
cannot do what you want without further coding. maybe some UDT will be
helpful and you can balance the effort on the java and UDF.


Rhino 写道：

> Is it possible to store Java objects in DB2 V8.2 for Windows/Unix/Linux via
> JDBC?
>
> Specifically, if I have a 4-dimensional boolean array, i.e. boolean[][][][],
> can I store it directly in a column of a DB2 table? If so, how do I do it?
>
> It would be VERY convenient if I could store this boolean array directly in
> a column of a DB2 table but I'm not at all clear on whether this is
> possible, even after reading the documentation in the Information Center.I
> was intrigued by the setObject() and getObject() methods in JDBC but I'm not
> at all sure if I can use them for the purpose I described. I'm especially
> unlclear about what datatype the column containing the Object could/should
> be.
>
> If I can't store a multidimensional boolean array directly in a table
> column, I can always convert it into a representation of the array that uses
> more traditional datatypes. For instance, I could convert:
>
> boolean[] myArray = {true, false, true};
>
> into this String:
>
> String myString = "TFT"; //T=true; F=false
>
> then store the String representation of the array in one of the CHAR column
> types. But it would be much more convenient if I could simply store the
> boolean[][][][] array directly in a column of the table. Does anyone knowif
> that is possible? If it is, a brief code snippet showing how to insert the
> value would be VERY helpful!
>
> --
> Rhino

Are you saying that it is definitely NOT possible to store a boolean array
directly in a DB2 table?

If it isn't possible to store the array directly, I can transform it into
something that can be stored and I'm not too worried about writing the code.
I'm mostly just trying to be 100% sure that there is no way to store the
array directly.

--
Rhino


"Hardy" <wyhang@gmail.com> wrote in message
news:1152026924.876240.269080@j8g2000cwa.googlegro ups.com...
It seems to be a programming strategy other than a database one. you
cannot do what you want without further coding. maybe some UDT will be
helpful and you can balance the effort on the java and UDF.


Rhino ??:

> Is it possible to store Java objects in DB2 V8.2 for Windows/Unix/Linux
> via
> JDBC?
>
> Specifically, if I have a 4-dimensional boolean array, i.e.
> boolean[][][][],
> can I store it directly in a column of a DB2 table? If so, how do I do it?
>
> It would be VERY convenient if I could store this boolean array directly
> in
> a column of a DB2 table but I'm not at all clear on whether this is
> possible, even after reading the documentation in the Information Center.
> I
> was intrigued by the setObject() and getObject() methods in JDBC but I'm
> not
> at all sure if I can use them for the purpose I described. I'm especially
> unlclear about what datatype the column containing the Object could/should
> be.
>
> If I can't store a multidimensional boolean array directly in a table
> column, I can always convert it into a representation of the array that
> uses
> more traditional datatypes. For instance, I could convert:
>
> boolean[] myArray = {true, false, true};
>
> into this String:
>
> String myString = "TFT"; //T=true; F=false
>
> then store the String representation of the array in one of the CHAR
> column
> types. But it would be much more convenient if I could simply store the
> boolean[][][][] array directly in a column of the table. Does anyone know
> if
> that is possible? If it is, a brief code snippet showing how to insert the
> value would be VERY helpful!
>
> --
> Rhino

Rhino wrote:
> Are you saying that it is definitely NOT possible to store a boolean array
> directly in a DB2 table?
>
> If it isn't possible to store the array directly, I can transform it into
> something that can be stored and I'm not too worried about writing the code.
> I'm mostly just trying to be 100% sure that there is no way to store the
> array directly.
DB2 does not support an ARRAY data type.
If all you want is store (you don't want to operate on it in DB2) then
you should linearize the array into a VARCHAR FOR BIT DATA or a BLOB (if
it's big). In C I would simply cast the beast to a char pointer and be
done with it. Not sure if there is anything similar brute but efficient
in Java :-)

Cheers
Serge
--
Serge Rielau
DB2 Solutions Development
IBM Toronto Lab

IOD Conference
http://www.ibm.com/software/data/ond...ness/conf2006/

"Serge Rielau" <srielau@ca.ibm.com> wrote in message
news:4gvienF1pib17U1@individual.net...
> Rhino wrote:
>> Are you saying that it is definitely NOT possible to store a boolean
>> array directly in a DB2 table?
>>
>> If it isn't possible to store the array directly, I can transform it into
>> something that can be stored and I'm not too worried about writing the
>> code. I'm mostly just trying to be 100% sure that there is no way to
>> store the array directly.
> DB2 does not support an ARRAY data type.

I knew that :-)

I was wondering if there was some way to store an Object though. If I could
stuff the boolean array into an Object, that would probably meet the users
needs. Being able to store the array directly would be even better, of
course, but that sounds like it's impossible.

By the way, do you have any idea when/if DB2 will support the ARRAY
datatype? Is it in Version 9 by any chance?

> If all you want is store (you don't want to operate on it in DB2) then you
> should linearize the array into a VARCHAR FOR BIT DATA or a BLOB (if it's
> big). In C I would simply cast the beast to a char pointer and be done
> with it. Not sure if there is anything similar brute but efficient in Java
> :-)
>
I can manage to linearize it easily enough with a little Java code. I just
wanted to see if there was any way to store it without having to linearize
and de-linearize it.

--
Rhino

Rhino wrote:
> By the way, do you have any idea when/if DB2 will support the ARRAY
> datatype? Is it in Version 9 by any chance?
Not in DB2 9. And if you want to know what's in Python you'll need an
NDA and sign your name in blood.
Can you define what you mean by an object? If you can pass DB2 the java
object in binary format it'll gladly store that.

Cheers
Serge
--
Serge Rielau
DB2 Solutions Development
IBM Toronto Lab

IOD Conference
http://www.ibm.com/software/data/ond...ness/conf2006/

Serge Rielau wrote:

> Rhino wrote:
>> By the way, do you have any idea when/if DB2 will support the ARRAY
>> datatype? Is it in Version 9 by any chance?
> Not in DB2 9. And if you want to know what's in Python you'll need an
> NDA and sign your name in blood.
> Can you define what you mean by an object? If you can pass DB2 the java
> object in binary format it'll gladly store that.
>
> Cheers
> Serge

Yep, usually (but unfortunattely not for all Java classes) you can serialize
an object in java and you get an array of bytes, which you can put into a
BLOB or VARCHAR FOR BIT DATA.

Best regards,
Kovi
--
-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-
| Gregor Kovac | Gregor.Kovac@mikropis.si |
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| In A World Without Fences Who Needs Gates? |
| Experience Linux. |
-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-

"Gregor Kovac" <gregor.kovac@mikropis.si> wrote in message
news:2XJqg.4125$oj5.1403580@news.siol.net...
> Serge Rielau wrote:
>
>> Rhino wrote:
>>> By the way, do you have any idea when/if DB2 will support the ARRAY
>>> datatype? Is it in Version 9 by any chance?
>> Not in DB2 9. And if you want to know what's in Python you'll need an
>> NDA and sign your name in blood.
>> Can you define what you mean by an object? If you can pass DB2 the java
>> object in binary format it'll gladly store that.
>>
>> Cheers
>> Serge
>
> Yep, usually (but unfortunattely not for all Java classes) you can
> serialize
> an object in java and you get an array of bytes, which you can put into a
> BLOB or VARCHAR FOR BIT DATA.
>

Thanks Gregor, I think you've just answered my question. It sounds like I
always need to convert all but the simplest of Objects to byte arrays for
storage in BLOBs or VARCHAR FOR BIT DATA columns. The only things I don't
need to convert to byte arrays are integers, doubles, floats,
dates/times/timestamps, and Strings: those can be stored directly in the
corresponding DB2 datatypes.

--
Rhino

"Serge Rielau" <srielau@ca.ibm.com> wrote in message
news:4h081bF1p3uvqU1@individual.net...
> Rhino wrote:
>> By the way, do you have any idea when/if DB2 will support the ARRAY
>> datatype? Is it in Version 9 by any chance?
> Not in DB2 9. And if you want to know what's in Python you'll need an NDA
> and sign your name in blood.

It's okay, I wasn't trying to find out anything that hadn't already been
revealed :-) I just thought there might have been some kind of announcement
about a general strategic direction with respect to datatype support for
coming versons of DB2.

> Can you define what you mean by an object? If you can pass DB2 the java
> object in binary format it'll gladly store that.
>
Virtually everything in Java is an Object. In fact, the only things that
aren't Objects are the primitives: short, int, long, boolean, char, and one
or two others. And even the primitives have wrapper classes that can turn
them into Objects. So pretty much anything you can imagine is an Object: a
File, a URL, a ResultSet, an Image, GUI components, etc. etc. etc.

I suppose I was just dreaming the impossible dream but when I saw methods
setObject() and getObject() it occurred to me it might mean that _any_ Java
Object might be storable in and retrievable from DB2 _DIRECTLY_. Then,
instead of having to linearize the data into a byte stream for the insert
and then convert it back when I read the data, I could just store it in its
original form and get it back that same way.

Naturally, I looked at the Java API and the DB2 documentation on setObject()
and getObject() but I found them very vague and they didn't answer the
question of whether they worked the way that I would have liked them to
work. But it now seems pretty clear that they DON'T work the way I wanted.

It struck me that my impossible dream might be something that DB2 will be
doing somewhere down the road and might even have been announced at some
point; I could have easily missed such an announcement. That's why I asked
whether it was coming in Viper or further down the road.

I'm going to hold on to a vague hope that direct storage of any Object in a
DB2 table will be possible some day but I'm going to make sure that I don't
expect "some day" to be any time soon :-)

In the meantime, I will convert Objects to byte arrays as I currently do
with JPGs or audio files. This is not really a problem. It would just be
that much more convenient if I didn't have to convert to or from byte arrays
to store and use my Objects.

--
Rhino



> Cheers
> Serge
> --
> Serge Rielau
> DB2 Solutions Development
> IBM Toronto Lab
>
> IOD Conference
> http://www.ibm.com/software/data/ond...ness/conf2006/

Rhino wrote:
> "Serge Rielau" <srielau@ca.ibm.com> wrote in message
> news:4h081bF1p3uvqU1@individual.net...
>> Rhino wrote:
>>> By the way, do you have any idea when/if DB2 will support the ARRAY
>>> datatype? Is it in Version 9 by any chance?
>> Not in DB2 9. And if you want to know what's in Python you'll need an NDA
>> and sign your name in blood.
>
> It's okay, I wasn't trying to find out anything that hadn't already been
> revealed :-) I just thought there might have been some kind of announcement
> about a general strategic direction with respect to datatype support for
> coming versons of DB2.
One new data type that you can look forward to is a decimal floating
point type. That cat is out of the bag.

Cheers
Serge
--
Serge Rielau
DB2 Solutions Development
IBM Toronto Lab

IOD Conference
http://www.ibm.com/software/data/ond...ness/conf2006/