On Nov 5, 2007 8:04 PM, Gokulakannan Somasundaram <gokul007@gmail.com > wrote:
There may not be anything called chain-pruning. Instead the tuples, which are to be vacuumed, will get vacuumed, after redirecting their index tuple peers, during the Vacuum process.
This won't help us check the heap bloat. Though containing index bloat is important, most of the performance benefits of HOT comes from doing page level retail vacuuming. This not only reduces the heap bloat but also results in less frequent vacuuming of the table.
Can you please explain this in more detail? If the HOT chain doesn't break and completely gets into a single page, the Vacuum daemon need not intervene with the HOT tuples for space reclamation. But ultimately the space would get reclaimed even with the normal Vacuum(without HOT Pruning). Isn't it? Then how do we say that without HOT Pruning, we will have Heap Bloat?