Expectations of Expected Row Size

[kevin_sherlock]

I should have written something down about this 3 years ago.   That's when I made a comment to a friend at the ISUG Tech conference that expected_row_size isn't exactly what you might think it is.  In fact, even if you set it to it's maximum allowable size, you can still see forwarded rows happen.  And, that's really what the docs say.  Well, it's subtle anyway.    Then, at this past year's conference (2015), I see it mentioned in a couple of presentations.  That prompted me to go find my old research, and try to dig a little deeper.

As a result, there is too much information to really make effective use of a "blog" entry, so I decided to create a series of videos on the subject.

The first video

SAP ASE 16 - What to Expect from Expected Row Size - Part 1 - YouTube

just discusses the topic and it's current documentation.

The second video

SAP ASE 16 - What to Expect from Expected Row Size - Part 2 - YouTube

goes into a demonstration and case study of the various behaviors, metrics, and how transactions can affect what rows get forwarded, and what rows stay on the page.

Space management is an interesting (and complicated) topic.  I'm sure those here who have access to the ASE code can elaborate more on the topic, but these are simply my observations from "the outside".  Comments are welcomed!