Re: Release Note Changes

Pavan Deolasee wrote:
> One of the improvements of HOT is to truncate a DEAD tuple to its
> line pointer. A DEAD tuple could be an old version of an updated
> tuple or a deleted tuple. When a tuple is truncated, the space used
> by the line pointer can not be reused (until the index entries are removed).
> But the space used by the actual tuple can be reused for a later update,
> after
> the page is defragmented. Note that this defragmentation can happen
> outside of a VACUUM.
>
> This gives us an ability to run VACUUM less frequently on a table. We
> still need to run VACUUM to remove the line pointer bloat, but may be less
> frequently for the given percentage of bloat. IMHO this should have a
> positive
> effect on performance atleast in an IO bound scenario.

I have updated the release note item title to mention DELETE as well:

Heap-Only Tuples (<acronym>HOT</>) accelerate space reuse for
most <command>UPDATE</>s and <command>DELETE</>s

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://postgres.enterprisedb.com

+ If your life is a hard drive, Christ can be your backup. +