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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