> On Dec 11, 2016, at 08:37, Melvin Davidson <melvin6...@gmail.com> wrote:
> 
> Yes, I see your point, but the case where the row does not fit into the same 
> block 
> would only occur with unlimited field types such as var[], bytea[], etc.

No, that's not correct either.  A block can fill up for any number of reasons: 
Dead tuples, a long HOT chain, or just a lot of data packed into the block.  
The first UPDATE to a tuple in a block that was populated by continuous INSERTs 
or a COPY, if the table is using the default fillfactor, will cause the new 
tuple to be written to a different block, which will cause an index update.

The important thing to remember is that the process you are describing (in 
which indexes are not updated unless a column involved in the index changes) is 
an optimization, Heap-Only Tuples.  It's a very common optimization, but it's 
not guaranteed.

--
-- Christophe Pettus
   x...@thebuild.com



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