Re: Some weird indexing recommendations I just got

You may in part have answered your own question if you got this information from the debugger and not ACS. The debugger "advice" has not been updated in eons and the SQL engine has come a long way. IBM has been warning for years not to use it.

If you did use the debug info I suggest you use the ACS index advisor instead.


Jon P.

On Feb 8, 2023, at 6:52 PM, James H. H. Lampert via MIDRANGE-L <midrange-l@xxxxxxxxxxxxxxxxxx> wrote:

I just put the debugger on an SQL query, and got a couple of indexing recommendations that appear downright nonsensical:

Of course, as usual, "the names have been changed to protect the innocent."

Both of them on file FOOBAR

First suggestion, index FOOBAR on FOO, CORGE. (FOOBAR is already uniquely keyed on FOO.)

Second suggestion, index FOOBAR on BAR, CORGE. (This makes a tiny bit more sense, but only a tiny bit: there's no uniqueness constraint on BAR, but there's already a logical non-uniquely keyed on BAR and BAZ, and also one on BAZ and BAR, and there are only a few values of BAR appearing in more than one record, only one with as many as 6, and none with more than that.)

Any idea why we'd get such nonsensical suggestions?

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JHHL
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