db file sequential read

During INSERT or UPDATE

If you see a lot of "db file sequential read" during an INSERT or UPDATE it could be due to...

  • Too many indexes.

  • A bug with ASSM (that existed in older versions of Oracle, disappeared by 11.2.0.4, then re-appeared in 12.1.0.2 and disappeared again by 12.2.0.1).

Refer to the excellent Johnathan Lewis article (ASSM-Argh) regarding this, linked below.

Bibliography


https://jonathanlewis.wordpress.com/2018/01/09/assm-argh/ Bug 20466322 - ASSM Free block space not reused when expected (Doc ID 20466322.8)
https://jonathanlewis.wordpress.com/2013/01/10/over-indexing/