Please see the version 11 of HOT patch posted on -patches.
The concept of marking the pruned tuples with LP_DELETE and
reusing such tuples for subsequent UPDATEs has been removed
and replaced with a simpler mechanism of repairing the page
fragmentation as and when possible.
The logic of chain pruning has been simplified a lot. In addition, there
are fewer new WAL log records. We rather reuse the existing WAL
record types to log the operations.
Few 4 hour DBT2 runs have confirmed that this simplification hasn't
taken away any performance gains, rather we are seeing better performance
with the changes. The gain can be attributed to the fact that now more
HOT updates are possible even if the tuple length changes between
updates (since we do the complete page defragmentation)
The changes are mostly isolated in the above area apart from some
stray bug fixes.