My customer's database has a gigantic table (hundreds of millions of records) and a SELECT
that, by cumulative use, is eating a huge chunk of processing time. Each exec takes almost a minute in average. (That's what AWR tells me, anyway.)
SELECT
MAX(fldA)
FROM
humongoustable
WHERE
fldB = :B2 AND fldC = :B1
There's only one index involving the above fields, and it's on (fldC, fldA, fldB)
.
I suspect that isn't helping any, and there should be two separate nonunique indices; one for fldA
and another for (fldB, fldC)
. Am I correct?