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In certain test cases, a large percentage of variable-length add operations failed because of duplicate keys. To account for these special cases, a PUTHDR() mode, ctADDUNQFRShdr, has been added that can enable a new way of managing variable-length record add operations. This allows an add record call to add unique keys before allocating space for the data record from the data file. If a unique key add fails, the ADDVREC() operation fails immediately. If it succeeds, the ADDVREC() operation continues.
In the test cases where a large percentage of ADDVREC() operations are expected to fail because of duplicate keys, up to a 35% performance gain has been observed.
In regular cases where the ADDVREC() seldom fails because of duplicate keys, enabling this feature may result in a small loss of performance.
