Re: Reading a Blob field using Hibernate

Thanks for looking into this! I don't know the size of my inputstream (it's
a file uploaded by a user), and I want to avoid reading it into a byte[]
first just to compute the size.

Note that we do have a size-limiting inputstream (not shown in this
example), to prevent users from uploading e.g. blu-ray images into our
database.


I'll be waiting for the next release!


Kind regards,

*Jeroen van der Vegt *Lead Designer

*T* +31 1 82 59 40 00
*A* Burgemeester Jamessingel 1, P.O. Box 2013, 2800 BD Gouda, The
Netherlands* | W* technolution.nl

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Op di 20 aug. 2019 om 15:47 schreef Fred Toussi via Hsqldb-user <
[email protected]>:

> Thanks for the code example Jeroen.
>
> Code attached. I have modified it to support in-procee mem: and
> server-based mem: databases with two profiles.
>
> The call to createBlob(stream, length) should specify the actual length of
> the stream. This call is translated to a JDBC call with the same
> parameters. I set the length to the length of your test string and it works
> fine in both profiles.
>
> Specifying a longer string raises an internal exception in HSQLDB that is
> not properly handled during the creation of the blob. The blob is not
> initialised properly and causes a problem when accessed later. I will fix
> this issue and will probably allow a stream that is shorter than the
> specified length. This will be done in the next few days and committed for
> the next release.
>
> See below for Hiberrnate method's JavaDoc
>
> Re the Server settings, the server has an internal database URL (file: or
> mem:) paired with its alias, for each database that it serves. The alias is
> not a schema, as there can be multiple schemas within a single database.
>
> Regards
>
> Fred
>
>
> https://github.com/hibernate/hibernate-orm/blob/master/hibernate-core/src/main/java/org/hibernate/engine/jdbc/LobCreator.java
>
> /**
> * Create a BLOB reference encapsulating the given binary stream.
> *
> * @param stream The binary stream to wrap as a blob.
> * @param length The length of the stream.
> * @return The created blob, castable to {@link Blob} as well as {@link
> BlobImplementer}
> */
> public Blob createBlob(InputStream stream, long length);
>
> On Mon, Aug 19, 2019, at 11:33, Jeroen van der Vegt wrote:
>
> Hi,
>
>
> The database was running all the time. I update my code to a fully working
> example.
>
> Using a file: database does change the error to this, but that isn't all
> that helpful:
>
> Caused by: org.hsqldb.HsqlException: file input/output error
> at org.hsqldb.error.Error.error(Unknown Source)
> at org.hsqldb.types.BlobDataID.getBytes(Unknown Source)
> at org.hsqldb.types.BlobInputStream.readIntoBuffer(Unknown Source)
>
>
> Kind regards,
> *Jeroen van der Vegt *Lead Designer
>
> *T* +31 1 82 59 40 00
> *A* Burgemeester Jamessingel 1, P.O. Box 2013, 2800 BD Gouda, The
> Netherlands* | W* technolution.nl
>
> This email is intended exclusively for the addressee(s), and may not be
> passed on to, or made available for use by any person other than the
> addressee(s). Technolution B.V. rules out any and every liability resulting
> from any electronic transmission.
>
>
> Op ma 19 aug. 2019 om 09:57 schreef Fred Toussi via Hsqldb-user <
> [email protected]>:
>
>
> Your code is for testing persistence. It works on Oracle, which is
> persistent, and fails on the HSQLDB mem: database, which is not persistent
> if the database is shutdown. Try using an HSQLDB file: database to get a
> closer match and report if there is still an issue.
>
> The stack trace shows the lob store is empty when you try to retrieve the
> lob. So in between saving the data and reading it back the database was
> probably closed.
>
> Regards
>
> Fred Toussi
>
> On Sun, Aug 18, 2019, at 18:30, Jeroen van der Vegt wrote:
>
> Hello all,
>
>
> I keep running into this exception, but I do not understand why as the
> code works fine using Oracle as a database.
> For this test, I'm using HSQLDB 2.5.0, Jdk 8.144 and Hibernate 5.2.18,
> with the default HSQLDialect in an in-memory HSQLDB database.
>
> I've attached some dummy java code which should make the code I'm using
> clear:
> First, there is a database entity class called 'MyAttachment', which
> stores binary data in a (java.sql.)Blob.
> For testing, I store a small amount of data ("this is a test".getBytes())
> in an inputStream, and store that as an attachment (see the
> streamToDb-method). This seems to work fine, as the Hsqldb DatabaseManager
> shows a records with (binary data) in it.
>
> When I try to retrieve the data however, it fails as soon as I try to
> access the InputStream (see the getAttachmentData-method). When updating
> the code to read some bytes instead of accessing a stream, I get the same
> exception (though not wrapped):
>
> java.io.IOException: java.lang.IndexOutOfBoundsException: Index out of
> bounds: 0 >= 0
> at org.hsqldb.lib.java.JavaSystem.toIOException(Unknown Source)
> at org.hsqldb.types.BlobInputStream.read(Unknown Source)
> at hsqldb.Test.test(Test.java:53)
> ...
> Caused by: java.lang.IndexOutOfBoundsException: Index out of bounds: 0 >= 0
> at org.hsqldb.lib.HsqlArrayList.get(Unknown Source)
> at org.hsqldb.persist.LobStoreMem.getBlockBytes(Unknown Source)
> at org.hsqldb.persist.LobManager.getBytesNormal(Unknown Source)
> at org.hsqldb.persist.LobManager.getBytes(Unknown Source)
> at org.hsqldb.Session.performLOBOperation(Unknown Source)
> at org.hsqldb.Session.execute(Unknown Source)
> at org.hsqldb.types.BlobDataID.getBytes(Unknown Source)
> at org.hsqldb.types.BlobInputStream.readIntoBuffer(Unknown Source)
> ... 33 more
>
>
> What is going wrong? As it works with Oracle, I suppose the problem is
> Hsqldb-specific?
>
>
> Kind regards,
>
> *Jeroen van der Vegt *Lead Designer
>
> *T* +31 1 82 59 40 00
> *A* Burgemeester Jamessingel 1, P.O. Box 2013, 2800 BD Gouda, The
> Netherlands* | W* technolution.nl
>
> This email is intended exclusively for the addressee(s), and may not be
> passed on to, or made available for use by any person other than the
> addressee(s). Technolution B.V. rules out any and every liability resulting
> from any electronic transmission.
>
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>
>
> *Attachments:*
>
>    - hsqldb_example.java
>
>
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>
> *Attachments:*
>
>    - TestBlob.java
>
>
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