Fix assertion failure when running pgbench -s.

If there is the WAL page that the continuation WAL record just fits within
(i.e., the continuation record ends just at the end of the page) and
the LSN in such page is specified with -s option, previously pg_waldump
caused an assertion failure. The cause of this assertion failure was that
XLogFindNextRecord() that pg_waldump -s calls mistakenly handled
such special WAL page.

This commit changes XLogFindNextRecord() so that it can handle
such WAL page correctly.

Back-patch to all supported versions.

Author: Andrey Lepikhov
Reviewed-by: Fujii Masao, Michael Paquier
Discussion: https://postgr.es/m/99303554-5dd5-06e6-f943-b3005ccd6edd@postgrespro.ru

diff --git a/src/backend/access/transam/xlogreader.c b/src/backend/access/transam/xlogreader.c
index 4c28ea64e3b8c6bea5745f0631076db1c42efd16..5c5e92cbd6eec29acf5a255633bf3f43a6cfbd36 100644 (file)
--- a/src/backend/access/transam/xlogreader.c
+++ b/src/backend/access/transam/xlogreader.c
@@ -976,7 +976,7 @@ XLogFindNextRecord(XLogReaderState *state, XLogRecPtr RecPtr)
             *
             * Note that record headers are MAXALIGN'ed
             */
-           if (MAXALIGN(header->xlp_rem_len) > (XLOG_BLCKSZ - pageHeaderSize))
+           if (MAXALIGN(header->xlp_rem_len) >= (XLOG_BLCKSZ - pageHeaderSize))
                tmpRecPtr = targetPagePtr + XLOG_BLCKSZ;
            else
            {