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  3. November 2009

Re: Logical file order of records

Dennis Lovelady wrote:

The order is not guaranteed beyond the fact that the key data
will be organized as requested. There is nothing more. The
algorithm for building the indexes (indices?) is ultra-complex,
and does not take RRN into consideration as might be supposed.
Even if two files in different libraries return the same value
with one query, they may not with the next (assuming data changes
have been made to one or both of them between the two queries).


The database does include in that /complexity/, the ability to specify the ordering of duplicate key values; e.g. LIFO, FIFO, FCFO, in DDS. Not all accesses to database data are via query, so realize that non-SQL & non-query interfaces used to read-by-key can actually effect a read-order to reflect whatever was specified as the [build]duplicate-key-order rule(s).

Regards, Chuck

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