4 Replies Latest reply: Feb 10, 2012 4:08 PM by damien.claveau RSS

    Semantic-table compression

    889820
      Hi,

      How to compress semantic data in Oracle 11g.
      Please provide more details (example) for the table compression technique in semantic (11.2.0.3.0)
        • 1. Re: Semantic-table compression
          alwu-Oracle
          Hi,

          We are using basic compression behind the scenes. Users don't need to do anything.
          For the tables in your own schema, you can add "compress" to the create table DDLs.
          An example can be found in slide #34 of the following document.
          http://download.oracle.com/otndocs/products/semantic_tech/pdf/semtech_howto.pdf


          If you have license for OLTP compression, then you can certainly turn it on for application table
          creation or staging table creation. Please see section 7.2.2 of the following document

          http://docs.oracle.com/cd/E11882_01/appdev.112/e11828/sem_jena.htm

          Thanks,

          Zhe Wu
          • 2. Re: Semantic-table compression
            damien.claveau
            Hi,

            Compressing the triple tables is highly recommanded for performance and storage reasons.

            However, if you are to enable versionning with Workspace Manager, it will fail during dbms_wm.disableversioning
            because the command dbms_wm.enableversioning only partially (with no exception) creates necessary oracle objects (triggers,...) on a compressed table.

            Full explanation is here [http://oracle-plsql10g.blogspot.com/2011/11/ora-20231-failed-during.html].
            (I'm not the author but I have had the same problem as described in the article).

            So, always compress triple table except if you use WM.

            Damien
            • 3. Re: Semantic-table compression
              alwu-Oracle
              Hi Damien,

              Which DB version are you using?

              I had a conversation with Oracle Workspace Manager dev team and I was told that the bug has been fixed in 11.1.0.7.

              Thanks,

              Zhe Wu
              • 4. Re: Semantic-table compression
                damien.claveau
                Hi Zhe,

                I have reproduced the error (with exactly the same procedure as described in the above link)
                using Oracle Enterprise Edition *11.2.0.1.0*, on Windows and Linux OS.

                Hopefully, my a RDF Model is of medium size (50 millions triples), and I have had no significant negative impact on performances without compressing.

                Damien