On Fri, 2024-03-15 at 13:12 +0530, Bharath Rupireddy wrote: > Hi, > > While working on [1], it was identified that > WaitXLogInsertionsToFinish emits a LOG message, and adjusts the upto > ptr to proceed further when caller requests to flush past the end of > generated WAL. There's a comment explaining no caller should ever do > that intentionally except in cases with bogus LSNs. For a similar > situation, XLogWrite emits a PANIC "xlog write request %X/%X is past > end of log %X/%X". Although there's no problem if > WaitXLogInsertionsToFinish emits LOG, but why can't it be a bit more > harsh and emit PANIC something like the attached to detect the corner > case? > > Thoughts?
I'm not clear on why the callers of WaitXLogInsertionsToFinish() are handling errors the way they are. XLogWrite PANICs, XLogFlush ERRORs (which is likely to be escalated to a PANIC anyway), and the other callers ignore the return value and leave it up to XLogWrite() to PANIC. As far as I can tell, once WaitXLogInsertionsToFinish() detects this bogus LSN, a PANIC is a likely outcome, so your proposed change makes sense. But then why are the callers also checking? I haven't looked in a lot of detail. Regards, Jeff Davis