Conference ilbbak::ibi_focus

84.0. "beware rdb and focus users" by TUNER::CARNEY () Tue Jun 28 1988 15:39

    This is something you rdb focus users should be aware of.
                                          
    I am running v5.0 FOCUS AND V2.3 RDB/VMS.
    I created a view in rdb that joins three relations. These relations
    contain 1 million records between them.  Then I used autordb to create
    the .mas and .acx files of this view.  I ran a query with this 
    configuration and let the job run for 48 hrs before killing it. 
    Obviously I had a perfomance problem.  I pounded my fist in the sand 
    for about a week trying to optimize my database by changing buffers,
    nodes sizes, etc..  I even used rdms$debug_flags to dump the
    optimization strategy.  This didn't look right.  But
    I figured IBI knew what they were doing when they used the DSRI
    (digital standard relational interface).  Eventually I reproduced
    the querey using RDO and the relations. I gave up on the view. 
    It ran in about 20 min.  I came to the conclusion
    that the problem was not with my database or my system but with the
    tools.  Then I created a master file that joined the relations
    explicitly. In other words, I created a master and access file with 
    segments for each relation. Then I ran my original query again and It ran 
    in 20 mins.                                           
    
    Therefore the problem is in one of two places. Either focus has
    not mastered their understanding of the DSRI or RDB has a problem
    with its optimization logic for reading views.  
    
    Does any one have any comment on this topic?
    Has any one else had the same problem?
                                           
    Mike
    
    

    Did you run RDO using the RDB view? and what were
    the results?

    AutoRDB is ok as far as it goes. BUT in my experiance I would always
    produce a .mas and a .acx file as this gives you just one file to
    refer to in FOCUS. 
    
    Leaving all the relations as seperate .mas files does not reflect
    the true structure of a RDB database and there for joining the
    relations is only a poor mans way round the problem. 
    
    Having an .acx with all the relations in it joined together as the
    are in RDB would make more sence and as you have seen this also
    allows FOCUS to perform correctly.
    
    So sum up it is always wise to take a little extra time when defining
    an RDB db and create the .mas and .acx for the whole thing. This
    also aids users in Tabletalk as it only gives them on filename to
    table as the whole database.
    
    Regards 
    
    Adam Linnell