Make GiST indexes on-disk compatible with 9.2 again.

The patch that turned XLogRecPtr into a uint64 inadvertently changed the
on-disk format of GiST indexes, because the NSN field in the GiST page
opaque is an XLogRecPtr. That breaks pg_upgrade. Revert the format of that
field back to the two-field struct that XLogRecPtr was before. This is the
same we did to LSNs in the page header to avoid changing on-disk format.

Bump catversion, as this invalidates any existing GiST indexes built on
9.3devel.

3 files changed, 29 insertions, 13 deletions

diff --git a/src/include/access/gist.h b/src/include/access/gist.h
index 69e4ec03fb..a487a0be3a 100644
--- a/src/include/access/gist.h
+++ b/src/include/access/gist.h
@@ -64,10 +64,15 @@
 #define F_FOLLOW_RIGHT		(1 << 3)	/* page to the right has no downlink */
 
 typedef XLogRecPtr GistNSN;
+/*
+ * For on-disk compatibility with pre-9.3 servers, NSN is stored as two
+ * 32-bit fields on disk, same as LSNs.
+ */
+typedef PageXLogRecPtr PageGistNSN;
 
 typedef struct GISTPageOpaqueData
 {
-	GistNSN		nsn;			/* this value must change on page split */
+	PageGistNSN	nsn;			/* this value must change on page split */
 	BlockNumber rightlink;		/* next page if any */
 	uint16		flags;			/* see bit definitions above */
 	uint16		gist_page_id;	/* for identification of GiST indexes */
@@ -137,6 +142,9 @@ typedef struct GISTENTRY
 #define GistMarkFollowRight(page) ( GistPageGetOpaque(page)->flags |= F_FOLLOW_RIGHT)
 #define GistClearFollowRight(page)	( GistPageGetOpaque(page)->flags &= ~F_FOLLOW_RIGHT)
 
+#define GistPageGetNSN(page) ( PageXLogRecPtrGet(GistPageGetOpaque(page)->nsn))
+#define GistPageSetNSN(page, val) ( PageXLogRecPtrSet(GistPageGetOpaque(page)->nsn, val))
+
 /*
  * Vector of GISTENTRY structs; user-defined methods union and picksplit
  * take it as one of their arguments
diff --git a/src/include/catalog/catversion.h b/src/include/catalog/catversion.h
index 1e235c6d1e..cd562ef40c 100644
--- a/src/include/catalog/catversion.h
+++ b/src/include/catalog/catversion.h
@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	201212081
+#define CATALOG_VERSION_NO	201301171
 
 #endif
diff --git a/src/include/storage/bufpage.h b/src/include/storage/bufpage.h
index 7758407098..8c887cab73 100644
--- a/src/include/storage/bufpage.h
+++ b/src/include/storage/bufpage.h
@@ -83,6 +83,21 @@ typedef uint16 LocationIndex;
 
 
 /*
+ * For historical reasons, the 64-bit LSN value is stored as two 32-bit
+ * values.
+ */
+typedef struct
+{
+	uint32		xlogid;			/* high bits */
+	uint32		xrecoff;		/* low bits */
+} PageXLogRecPtr;
+
+#define PageXLogRecPtrGet(val) \
+	((uint64) (val).xlogid << 32 | (val).xrecoff)
+#define PageXLogRecPtrSet(ptr, lsn) \
+	((ptr).xlogid = (uint32) ((lsn) >> 32),	(ptr).xrecoff = (uint32) (lsn))
+
+/*
  * disk page organization
  *
  * space management information generic to any page
@@ -120,13 +135,6 @@ typedef uint16 LocationIndex;
  * are 15 bits.
  */
 
-/* for historical reasons, the LSN is stored as two 32-bit values. */
-typedef struct
-{
-	uint32		xlogid;			/* high bits */
-	uint32		xrecoff;		/* low bits */
-} PageXLogRecPtr;
-
 typedef struct PageHeaderData
 {
 	/* XXX LSN is member of *any* block, not only page-organized ones */
@@ -319,13 +327,13 @@ typedef PageHeaderData *PageHeader;
 	  / sizeof(ItemIdData)))
 
 /*
- * Additional macros for access to page headers
+ * Additional macros for access to page headers. (Beware multiple evaluation
+ * of the arguments!)
  */
 #define PageGetLSN(page) \
-	((uint64) ((PageHeader) (page))->pd_lsn.xlogid << 32 | ((PageHeader) (page))->pd_lsn.xrecoff)
+	PageXLogRecPtrGet(((PageHeader) (page))->pd_lsn)
 #define PageSetLSN(page, lsn) \
-	(((PageHeader) (page))->pd_lsn.xlogid = (uint32) ((lsn) >> 32),	\
-	 ((PageHeader) (page))->pd_lsn.xrecoff = (uint32) (lsn))
+	PageXLogRecPtrSet(((PageHeader) (page))->pd_lsn, lsn)
 
 /* NOTE: only the 16 least significant bits are stored */
 #define PageGetTLI(page) \