> > Another reliable approach would be to make the > > code wait before reading the record in the internal loop of > > ReadPageInternal() with an injection point when we know that we have a > > contrecord, but I'm not really excited about this prospect in > > xlogreader.c which can be also used in the frontend. > > Per my understanding an injection point must be added while flushing a WAL > record, > to emulate the incomplete WAL record issue. To confirm, how can it be used in > ReadPageInternal()?
I've spent time how we use the injection point to cause the same situation, which generates the OVERWRITE_CONTRECORD in-between the page, but it seems difficult. XLogFlush()->XLogWrite() has a responsibility to flush WAL records, but it does not write/flush per pages. It tries to write to pages as much as possible and flushes the result at once. A corner case is when the segment is changed, but this is not the same situation we observed the failure. So... I have no idea to create deterministic reproducers, it is OK for me to use 046 test for the purpose. Best regards, Hayato Kuroda FUJITSU LIMITED
