Andres Freund wrote: > On 2018-04-19 16:56:59 -0300, Alvaro Herrera wrote: > > Michael Paquier wrote: > > > > > Then, let's consider the beginning of the first commit fest of v12 as > > > judgement. Implementing radix tree for shared buffers is a long-term > > > project, which has no guarantee to get merged, while a visibly-simple > > > reloptions which helps in some cases... > > > > In the scenario we studied, the truncations were causing periodic > > hiccups which were quite severe. > > Was that with the current logic of breaking the truncations into smaller > chunks?
Yes -- it was with 9.5.7. I was skeptical about that stuff working correctly for a toast table, BTW, but I didn't manage to prove anything. > > The truncations were completely useless anyway because the table > > grew back to the original size daily (a few dozen GBs I think). > > That was a lot of unnecessary work, and under exclusive lock no > > less. > > FWIW, One goal of the different buffer mapping implementation is to also > make both increasing and decreasing size of relations possible without > an AEL. Oh, that sounds very useful. -- Álvaro Herrera https://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
