HIGH CURRENT BUFFER GETS HAPPENS DURING HCC ARRARY INSERT OPERATION SHORTLY AFTER MIGRATION TO 19.13 (Doc ID 2936230.1)

Last updated on APRIL 17, 2023

Applies to:

Symptoms

Recently, an exadata DB  was migrated to 19.13 from 11.2.0.4
By the way, buffer gets(logical read, especially current buffer) dramatically increased in 19.13.
The buffer gets in 19.13 is over 100 times lager than it in 11.2.0.3. So I checked AWR reports and Ifound out lots of array inserts kept being executed in the system and parts of those array inserts read so many blocks to search free blocks. Hence,I tried to change the values of  _assm_examination_*  parameter and then array insert performance was quite improved and high buffer gets were also decreased dramatically. Instead, space usage stared to increase dramatically.  So we need to check why array inserts in 19.13 access more huge  blocks than that in 11.2.0.4

Changes

 Exadata DB  was migrated to 19.13 from 11.2.0.4

Cause

My Oracle Support provides customers with access to over a million knowledge articles and a vibrant support community of peers and Oracle experts.