Re: Heap WARM Tuples - Design Draft

On 2016-08-04 12:55:25 -0400, Bruce Momjian wrote:
> On Thu, Aug  4, 2016 at 09:31:18AM -0700, Andres Freund wrote:
> > Hi,
> > 
> > On 2016-08-04 16:29:09 +0530, Pavan Deolasee wrote:
> > > Indexes whose values do not change do not require new index pointers. Only
> > > the index whose key is being changed will need a new index entry. The new
> > > index entry will be set to the CTID of the root line pointer.
> > 
> > That seems to require tracing all hot-chains in a page, to actually
> > figure out what the root line pointer of a warm-updated HOT tuple is,
> > provided it's HOT_UPDATED itself.  Or have you found a smart way to
> > figure that out?
> 
> The index points to the head of the HOT chain, and you just walk the
> chain on the page --- on need to look at other chains on the page.

When doing an update, you'll need to re-find the root tuple, to insert
the root ctid for the new index tuples.