On 5 June 2018 at 14:45, Alexander Korotkov <a.korot...@postgrespro.ru> wrote:
> Currently _bt_search() always locks leaf buffer in shared mode (aka BT_READ), > while caller can relock it later. However, I don't see what prevents > _bt_search() > from locking leaf immediately in exclusive mode (aka BT_WRITE) when required. > When traversing downlink from non-leaf page of level 1 (lowest level of > non-leaf > pages just prior to leaf pages), we know that next page is going to be leaf. > In > this case, we can immediately lock next page in exclusive mode if required. > For sure, it might happen that we didn't manage to exclusively lock leaf in > this > way when _bt_getroot() points us to leaf page. But this case could be handled > in _bt_search() by relock. Please, find implementation of this approach in > the > attached patch. It's a good idea. How does it perform with many duplicate entries? -- Simon Riggs http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
