On 12/9/20 3:21 AM, Hou, Zhijie wrote:
Hi
Since ba3e76c,
the optimizer call generate_useful_gather_paths instead of
generate_gather_paths() outside.
But I noticed that some comment still talking about generate_gather_paths not
generate_useful_gather_paths.
I think we should fix these comment, and I try to replace these " generate_gather_paths "
with " generate_useful_gather_paths "
Thanks. I started looking at this a bit more closely, and I think most
of the changes are fine - the code was changed to call a different
function, but the comments still reference generate_gather_paths().
The one exception seems to be create_ordered_paths(), because that
comment also makes statements about what generate_gather_pathes is
doing. And some of it does not apply to generate_useful_gather_paths.
For example it says it generates order-preserving Gather Merge paths,
but generate_useful_gather_paths also generates paths with sorts (which
are clearly not order-preserving).
So I think this comment will need a bit more work to update ...
regards
--
Tomas Vondra
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
