On 20 February 2018 at 16:07, Konstantin Knizhnik <k.knizh...@postgrespro.ru> wrote: > > > On 20.02.2018 14:26, Simon Riggs wrote: >> >> Try locking the root tid rather than the TID, that is at least unique >> per page for a chain of tuples, just harder to locate. >> > As far as I understand, it is necessary to traverse the whole page to locate > root tuple, isn't it? > If so, then I expect it to be too expensive operation. Scanning the whole > page on tuple update seems to be not an acceptable solution.
Probably. It occurs to me that you can lock the root tid in index_fetch_heap(). I hear other DBMS lock via the index. However, anything you do with tuple locking could interact badly with heap_update and the various lock modes, so be careful. You also have contention for heap_page_prune_opt() and with SELECTs to consider, so I think you need to look at both page and tuple locking. -- Simon Riggs http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
