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- 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 c8b0d2303d3242d4116da8e94ce46211061e6828..6d8581919c9fc348d883a9bdba09a344a6043472 100644 (file)
--- a/src/backend/access/transam/xlogreader.c
+++ b/src/backend/access/transam/xlogreader.c
@@ -966,7 +966,7 @@ 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
                        {