Re: Querying GV$ASM_DISKGROUP is slow
- From: Mladen Gogala <gogala.mladen@xxxxxxxxx>
- To: oracle-l@xxxxxxxxxxxxx
- Date: Mon, 6 Dec 2021 00:42:07 -0500
On 12/5/21 23:49, Jon Crisler wrote:
How many rows in X$KFGRP, 15 ? I have never run into this issue
anywhere from 11.x to 19c, but with only 15 rows maybe a FTS is expected.
Well, with only 15 rows in the table, the whole table is contained in a
single block. FTS is by definition the fastest method to read a single
block. I was having problems with that when I was working with EMP and
DEPT tables, also both contained in a single block. I was getting hash
join when I was doing WHERE d.deptno = e.deptno and I was expecting
nested loop join. Optimizer decision to use FTS is correct in both cases.
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Mladen Gogala
Database Consultant
Tel: (347) 321-1217
https://dbwhisperer.wordpress.com
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