Record data_checksum_version in control file.

The value is not used anywhere in code, but will
allow future changes to the checksum version
should that become necessary in the future.

src/backend/access/transam/xlog.c

@@ -60,7 +60,7 @@
 #include "utils/timestamp.h"
 #include "pg_trace.h"
 
-extern bool bootstrap_data_checksums;
+extern uint32 bootstrap_data_checksum_version;
 
 /* File path names (all relative to $PGDATA) */
 #define RECOVERY_COMMAND_FILE	"recovery.conf"
@@ -3797,7 +3797,7 @@ bool
 DataChecksumsEnabled(void)
 {
 	Assert(ControlFile != NULL);
-	return ControlFile->data_checksums;
+	return (ControlFile->data_checksum_version > 0);
 }
 
 /*
@@ -4126,7 +4126,7 @@ BootStrapXLOG(void)
 	ControlFile->max_prepared_xacts = max_prepared_xacts;
 	ControlFile->max_locks_per_xact = max_locks_per_xact;
 	ControlFile->wal_level = wal_level;
-	ControlFile->data_checksums = bootstrap_data_checksums;
+	ControlFile->data_checksum_version = bootstrap_data_checksum_version;
 
 	/* some additional ControlFile fields are set in WriteControlFile() */
 

src/backend/bootstrap/bootstrap.c

@@ -34,6 +34,7 @@
 #include "postmaster/walwriter.h"
 #include "replication/walreceiver.h"
 #include "storage/bufmgr.h"
+#include "storage/bufpage.h"
 #include "storage/ipc.h"
 #include "storage/proc.h"
 #include "tcop/tcopprot.h"
@@ -48,7 +49,7 @@
 extern int	optind;
 extern char *optarg;
 
-bool bootstrap_data_checksums = false;
+uint32 bootstrap_data_checksum_version = 0;  /* No checksum */
 
 
 #define ALLOC(t, c)		((t *) calloc((unsigned)(c), sizeof(t)))
@@ -262,7 +263,7 @@ AuxiliaryProcessMain(int argc, char *argv[])
 				SetConfigOption("fsync", "false", PGC_POSTMASTER, PGC_S_ARGV);
 				break;
 			case 'k':
-				bootstrap_data_checksums = true;
+				bootstrap_data_checksum_version = PG_DATA_CHECKSUM_VERSION;
 				break;
 			case 'r':
 				strlcpy(OutputFileName, optarg, MAXPGPATH);

src/bin/pg_controldata/pg_controldata.c

@@ -287,7 +287,7 @@ main(int argc, char *argv[])
 		   (ControlFile.float4ByVal ? _("by value") : _("by reference")));
 	printf(_("Float8 argument passing:              %s\n"),
 		   (ControlFile.float8ByVal ? _("by value") : _("by reference")));
-	printf(_("Data page checksums:                  %s\n"),
-		   (ControlFile.data_checksums ? _("enabled") : _("disabled")));
+	printf(_("Data page checksum version:           %u\n"),
+		   ControlFile.data_checksum_version);
 	return 0;
 }

src/bin/pg_resetxlog/pg_resetxlog.c

@@ -624,8 +624,8 @@ PrintControlValues(bool guessed)
 		   (ControlFile.float4ByVal ? _("by value") : _("by reference")));
 	printf(_("Float8 argument passing:              %s\n"),
 		   (ControlFile.float8ByVal ? _("by value") : _("by reference")));
-	printf(_("Data page checksums:                  %s\n"),
-		   (ControlFile.data_checksums ? _("enabled") : _("disabled")));
+	printf(_("Data page checksum version:           %u\n"),
+		   ControlFile.data_checksum_version);
 }
 
 

src/include/catalog/pg_control.h

@@ -213,8 +213,8 @@ typedef struct ControlFileData
 	bool		float4ByVal;	/* float4 pass-by-value? */
 	bool		float8ByVal;	/* float8, int8, etc pass-by-value? */
 
-	/* Are data pages protected by checksums? */
-	bool		data_checksums;
+	/* Are data pages protected by checksums? Zero if no checksum version */
+	uint32		data_checksum_version;
 
 	/* CRC of all above ... MUST BE LAST! */
 	pg_crc32	crc;

src/include/storage/bufpage.h

@@ -189,9 +189,12 @@ typedef PageHeaderData *PageHeader;
  * Release 8.3 uses 4; it changed the HeapTupleHeader layout again, and
  *		added the pd_flags field (by stealing some bits from pd_tli),
  *		as well as adding the pd_prune_xid field (which enlarges the header).
+ *
+ * As of Release 9.3, the checksum version must also be considered when
+ * handling pages.
  */
 #define PG_PAGE_LAYOUT_VERSION		4
-
+#define PG_DATA_CHECKSUM_VERSION	1
 
 /* ----------------------------------------------------------------
  *						page support macros