On Sun, Dec 26, 2021 at 10:36 AM SATYANARAYANA NARLAPURAM < satyanarlapu...@gmail.com> wrote:
> >> Actually all the WAL insertions are done under a critical section (except >> few exceptions), that means if you see all the references of XLogInsert(), >> it is always called under the critical section and that is my main worry >> about hooking at XLogInsert level. >> > > Got it, understood the concern. But can we document the limitations of the > hook and let the hook take care of it? I don't expect an error to be thrown > here since we are not planning to allocate memory or make file system calls > but instead look at the shared memory state and add delays when required. > > Yet another problem is that if we are in XlogInsert() that means we are holding the buffer locks on all the pages we have modified, so if we add a hook at that level which can make it wait then we would also block any of the read operations needed to read from those buffers. I haven't thought what could be better way to do this but this is certainly not good. -- Regards, Dilip Kumar EnterpriseDB: http://www.enterprisedb.com
