On Thu, Aug 4, 2016 at 09:58:29AM -0700, Andres Freund wrote:
> 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.
Ah, I had not thought of that --- good point.
-- Bruce Momjian <bruce@momjian.us> http://momjian.us EnterpriseDB
http://enterprisedb.com
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