Re: Querying GV$ASM_DISKGROUP is slow
From: Mladen Gogala <gogala.mladen_at_gmail.com>
Date: Mon, 6 Dec 2021 00:42:07 -0500
Message-ID: <3f0ff845-4458-206c-a3c1-b3289d4ff3ea_at_gmail.com>
Date: Mon, 6 Dec 2021 00:42:07 -0500
Message-ID: <3f0ff845-4458-206c-a3c1-b3289d4ff3ea_at_gmail.com>
On 12/5/21 23:49, Jon Crisler wrote:
> How many rows in X$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.
-- Mladen Gogala Database Consultant Tel: (347) 321-1217 https://dbwhisperer.wordpress.com -- http://www.freelists.org/webpage/oracle-lReceived on Mon Dec 06 2021 - 06:42:07 CET