Re: RSS Visual Explain index advisor

Hi David,

always take the index recommendations with a grain of salt.

It always recommends a lot of indexes, that it will never use, because as you said the "cost" of doing a table scan is sometimes lower than doing an index scan and a table lookup.

Explain is good - and it can really help - but you can do a lot manually by looking up indexes and creating JOIN and WHERE clauses to match them.

HTH
Daniel

Am 12.02.2026 um 15:39 schrieb David Gibbs via MIDRANGE-L <midrange-l@xxxxxxxxxxxxxxxxxx>:

Folks:

I'm a bit confused ... I've got a query that performs some joins and record
selections.

I ran it through visual explain (VE) and reviewed the indexes it
recommended.

I created those indexes and re-ran VE ... It no longer recommended those
indexes, but the diagram it showed remained the same. It appears that it
didn't actually USE the indexes it previously recommended.

When I viewed the indexes considered, the newly created indexes had a
reason code of 4 because the cost to use the access path was higher than
the cost of the chosen access path.

Any idea why it would recommend access paths and then disregard them once
they exist?

Thanks!

david
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