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  1. #1
    Join Date
    Feb 2005
    Posts
    118

    Unanswered: Sort heap threshold

    Using UDB DB2 ver 7.2 for AIX

    I noticed that the SORTHEAP is set to 51200 and SHEAPTHRES is set to 20000.
    Since the sort heap cannot exceed the sort heap threshold, clearly these values are meaningless from a tuning point of view.
    Now my question is what does DB2 do when it encounters such conflicting values ? Does it simply go and use the default values ? or does it treat the sort heap threshold are the correct value and makes ajustments to the sort heap accordingly ?
    As an extension of this question, my question is how does db2 handle the values at the database level when they don't agree with what is specified at the database manager level ?
    There are many db parameters(such as buffpage, dbheap,logbufsz etc) that make up the database global memory. Same with private memory, that is there are many parms that go into defining the private memory.
    So how does db2 reconcile the discrepancies that arise from setting the incorrect values (values that either don't make sense or simply cannot be done) of various configuration parameters ?
    looking forward to hear from you all.

    thanks and regards,
    Anil

  2. #2
    Join Date
    Jan 2005
    Posts
    191
    My guess is that this is equivalent to specifying SORTHEAP 20000.

    Generally, DB2 will apply restrictions from the most global through to the most localised. It might be a deliberate decision to have an instance memory limit that is less than the sum of the database limits. In this case the last database to ask for memory might not get all it wants.

    James Campbell

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