Add GUC ignore_invalid_pages.

Detection of WAL records having references to invalid pages
during recovery causes PostgreSQL to raise a PANIC-level error,
aborting the recovery. Setting ignore_invalid_pages to on causes
the system to ignore those WAL records (but still report a warning),
and continue recovery. This behavior may cause crashes, data loss,
propagate or hide corruption, or other serious problems.
However, it may allow you to get past the PANIC-level error,
to finish the recovery, and to cause the server to start up.

Author: Fujii Masao
Reviewed-by: Michael Paquier
Discussion: https://www.postgresql.org/message-id/CAHGQGwHCK6f77yeZD4MHOnN+PaTf6XiJfEB+Ce7SksSHjeAWtg@mail.gmail.com

1 files changed, 7 insertions, 2 deletions

diff --git a/src/backend/access/transam/xlogutils.c b/src/backend/access/transam/xlogutils.c
index b55c3833703..b217ffa52ff 100644
--- a/src/backend/access/transam/xlogutils.c
+++ b/src/backend/access/transam/xlogutils.c
@@ -31,6 +31,9 @@
 #include "utils/rel.h"
 
 
+/* GUC variable */
+bool		ignore_invalid_pages = false;
+
 /*
  * During XLOG replay, we may see XLOG records for incremental updates of
  * pages that no longer exist, because their relation was later dropped or
@@ -93,7 +96,8 @@ log_invalid_page(RelFileNode node, ForkNumber forkno, BlockNumber blkno,
 	if (reachedConsistency)
 	{
 		report_invalid_page(WARNING, node, forkno, blkno, present);
-		elog(PANIC, "WAL contains references to invalid pages");
+		elog(ignore_invalid_pages ? WARNING : PANIC,
+			 "WAL contains references to invalid pages");
 	}
 
 	/*
@@ -240,7 +244,8 @@ XLogCheckInvalidPages(void)
 	}
 
 	if (foundone)
-		elog(PANIC, "WAL contains references to invalid pages");
+		elog(ignore_invalid_pages ? WARNING : PANIC,
+			 "WAL contains references to invalid pages");
 
 	hash_destroy(invalid_page_tab);
 	invalid_page_tab = NULL;