Fix determination of broken LSN in OVERWRITTEN_CONTRECORD

In commit ff9f111bce24 I mixed up inconsistent definitions of the LSN of
the first record in a page, when the previous record ends exactly at the
page boundary.  The correct LSN is adjusted to skip the WAL page header;
I failed to use that when setting XLogReaderState->overwrittenRecPtr,
so at WAL replay time VerifyOverwriteContrecord would refuse to let
replay continue past that record.

Backpatch to 10.  9.6 also contains this bug, but it's no longer being
maintained.

Discussion: https://postgr.es/m/45597.1637694259@sss.pgh.pa.us

diff --git a/src/backend/access/transam/xlogreader.c b/src/backend/access/transam/xlogreader.c
index 26bdd4c102e718681f0f5a4d2f68a6019e687329..26f8e0ae2c650b93302ec68a43539d87f98a0649 100644 (file)
--- a/src/backend/access/transam/xlogreader.c
+++ b/src/backend/access/transam/xlogreader.c
@@ -415,7 +415,7 @@ restart:
                         */
                        if (pageHeader->xlp_info & XLP_FIRST_IS_OVERWRITE_CONTRECORD)
                        {
-                               state->overwrittenRecPtr = state->currRecPtr;
+                               state->overwrittenRecPtr = RecPtr;
                                ResetDecoder(state);
                                RecPtr = targetPagePtr;
                                goto restart;