Re: Performance Improvement by reducing WAL for Update Operation

On 11 January 2013 14:24, Amit Kapila <amit.kapila@huawei.com> wrote:

> http://archives.postgresql.org/message-id/6C0B27F7206C9E4CA54AE035729E9C3828
> 52DE51@szxeml509-mbs
>
> 1. However Heikki has pointed, it has some problems similar to for HOT
> implementation and that is the reason we have done memcmp for HOT.
> 2. Also we have found in initial readings that this doesn't have any
> performance difference as compare to current Approach.

OK, forget that idea.

>> I've moved this to the next CF. I'm planning to review this one first.
>
> Thank you.

Just reviewing the patch now, making more sense with comments added.

In heap_delta_encode() do we store which columns have changed? Do we
store the whole new column value?

-- Simon Riggs                   http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training & Services