Is there any way to speed up OPNQRYF on large files?
When using OPNQRYF, I try to keep the number of records being queried as small as possible. If this is for a report, you may be able to produce a subset of records to a separate file and then do an OPNQRYF over the subsetted file to speed things up. If all else fails and you have to run OPNQRYF over a large file, OPNQRYF will run faster if it can take advantage of an existing access path that matches your record selection criteria. If there is not a suitable access path for OPNQRYF to use, it will create the access path at the time of execution, which will slow down the OPNQRYF process.
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This was first published in October 2001