Magnus Hagander <mag...@hagander.net> writes: > On Tue, Apr 3, 2018 at 8:29 PM, Tom Lane <t...@sss.pgh.pa.us> wrote: >> It's scribbling on the source cluster's disk files and assuming that that >> translates one-for-one to what gets sent to the slave server --- but what >> if some of the blocks that it modifies on-disk are resident in the >> source's shared buffers? I think you'd have to shut down the source and >> then apply the corruption if you want stable results.
> It doesn't actually use a slave server as part of the tests. > And basebackups don't read from the sources shared buffers, but it *does* > read from the kernel buffers. Right, so the failure case occurs when the source server writes back a dirty page from its shared buffers to disk, in between the test script's corrupting that page on-disk and then trying to read it. Again, you'd have several orders of magnitude better chance of getting reproducible behavior if you were targeting something that wasn't a system catalog. regards, tom lane