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BRIN revmap pages are not standard pages ...
... and therefore we ought not to tell XLogRegisterBuffer the opposite,when writing XLog for a brin update that moves the index tuple to adifferent page. Otherwise, xlog insertion would try to "compress thehole" when producing a full-page image for it; but since we don't updatepd_lower/upper, the hole covers the whole page. On WAL replay, therevmap page becomes empty and so the entire portion of the index isuseless and needs to be recomputed.This is low-probability: a BRIN update only moves an index tuple to adifferent page when the summary tuple is larger than the existing one,which doesn't happen with fixed-width datatypes. Also, the revmappage must be first after a checkpoint.Report and patch: Kuntal GhoshBug is alleged to have detected by a WAL-consistency-checking tool.Discussion:https://postgr.es/m/CAGz5QCJ=00UQjScSEFbV=0qO5ShTZB9WWz_Fm7+Wd83zPs9Geg@mail.gmail.comI posted a test case demonstrating the problem, but I'm refraining fromadding it to the test suite; if the WAL consistency tool makes it in,that will be a better way to catch this from regressing. (We shoulddefinitely have someting that causes not-same-page updates, though.)1 parent961bed0 commit7403561
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