Allow I/O reliability checks using 16-bit checksums

Checksums are set immediately prior to flush out of shared buffers
and checked when pages are read in again. Hint bit setting will
require full page write when block is dirtied, which causes various
infrastructure changes. Extensive comments, docs and README.

WARNING message thrown if checksum fails on non-all zeroes page;
ERROR thrown but can be disabled with ignore_checksum_failure = on.

Feature enabled by an initdb option, since transition from option off
to option on is long and complex and has not yet been implemented.
Default is not to use checksums.

Checksum used is WAL CRC-32 truncated to 16-bits.

Simon Riggs, Jeff Davis, Greg Smith
Wide input and assistance from many community members. Thank you.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/include/access/visibilitymap.h b/src/include/access/visibilitymap.h
index 99b2dc5bb65..43789c230fc 100644
--- a/src/include/access/visibilitymap.h
+++ b/src/include/access/visibilitymap.h
@@ -24,8 +24,8 @@ extern void visibilitymap_clear(Relation rel, BlockNumber heapBlk,
 extern void visibilitymap_pin(Relation rel, BlockNumber heapBlk,
 				  Buffer *vmbuf);
 extern bool visibilitymap_pin_ok(BlockNumber heapBlk, Buffer vmbuf);
-extern void visibilitymap_set(Relation rel, BlockNumber heapBlk,
-				  XLogRecPtr recptr, Buffer vmbuf, TransactionId cutoff_xid);
+extern void visibilitymap_set(Relation rel, BlockNumber heapBlk, Buffer heapBuf,
+				  XLogRecPtr recptr, Buffer vmBuf, TransactionId cutoff_xid);
 extern bool visibilitymap_test(Relation rel, BlockNumber heapBlk, Buffer *vmbuf);
 extern BlockNumber visibilitymap_count(Relation rel);
 extern void visibilitymap_truncate(Relation rel, BlockNumber nheapblocks);