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From Andrew Cobley <a.e.cob...@dundee.ac.uk>
Subject Re: Issue retrieving blobs with CQL
Date Wed, 19 Mar 2014 13:26:57 GMT
Apologies,

this seems to be addressed in the thread :

https://groups.google.com/a/lists.datastax.com/forum/#!searchin/java-driver-user/blob$20ByteBuffer/java-driver-user/4_KegVX0teo/2OOZ8YOwtBcJ

Andy

On 19 Mar 2014, at 11:55, Andrew Cobley <a.e.cobley@dundee.ac.uk<mailto:a.e.cobley@dundee.ac.uk>>
wrote:

Cassandra 2.0.4

I’m using blobs to save and retrieve images in cassanda.   However the  blob I get back
is not the blob I saved !

I’m saving to CQL like this:

byte[] b= {(byte)10,(byte)20,(byte)30};
int length=b.length;
ByteBuffer buffer =ByteBuffer.wrap(b);
Session session = cluster.connect("keyspace2");
PreparedStatement ps = session.prepare("insert into tweets ( image, user, interaction_time,imagelength)
values(?,?,?,?)");
BoundStatement boundStatement = new BoundStatement(ps);
session.execute( boundStatement.bind( buffer, "majed",  convertor.getTimeUUID(),length));

and retrieving like this:

Session session = cluster.connect("keyspace2");
PreparedStatement ps = session.prepare("select image,user,imagelength from tweets where user
=?");
BoundStatement boundStatement = new BoundStatement(ps);
ResultSet rs =session.execute(boundStatement.bind( "majed"));
ByteBuffer bImage=null;
for (Row row : rs) {
   bImage = row.getBytes("image") ;
   System.out.println ("Image ");
   for (int i=0; i< 40;i++){
      System.out.print(String.format("%x ",bImage.get(i)));
       if ((i+1)%16 ==0) System.out.println();
   }
   System.out.println();
}
session.close();

So, I should be saving byte array of 3 long, and the  buffer in the save section is correct.
 However when I run the retrieve section I’m getting back the following:

82 0 0 8 0 0 0 28 0 0 0 2 0 0 0 5
0 0 0 3 0 0 0 1 0 0 0 3 a 14 1e

You can see the saved bytes are the last three and there is extra padding at the front.

Worse if I change the Select statement to:
PreparedStatement ps = session.prepare("select user,image,imagelength from tweets where user
=?”);

I get back:

82 0 0 8 0 0 0 28 0 0 0 2 0 0 0 5
0 0 0 3 0 0 0 1 0 0 0 5 6d 61 6a 65
64 0 0 0 3 a 14 1e

If you look you can see the username “majed” in the returned blob (6d 61 6a 65 64).

any ideas whats going on here ?

Many thanks

Andy

The University of Dundee is a registered Scottish Charity, No: SC015096


The University of Dundee is a registered Scottish Charity, No: SC015096

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