Assorted comment fixes, mostly just typos, but some obsolete statements.

YAMAMOTO Takashi

src/backend/access/gist/gist.c

@@ -253,7 +253,7 @@ gistplacetopage(Relation rel, Size freespace, GISTSTATE *giststate,
 		}
 
 		/*
-		 * Now that we know whick blocks the new pages go to, set up downlink
+		 * Now that we know which blocks the new pages go to, set up downlink
 		 * tuples to point to them.
 		 */
 		for (ptr = dist; ptr; ptr = ptr->next)

src/backend/access/gist/gistproc.c

 /*-------------------------------------------------------------------------
  *
  * gistproc.c
- *	  Support procedures for GiSTs over 2-D objects (boxes, polygons, circles).
+ *	  Support procedures for GiSTs over 2-D objects (boxes, polygons, circles,
+ *	  points).
  *
  * This gives R-tree behavior, with Guttman's poly-time split algorithm.
  *

src/backend/access/gist/gistsplit.c

@@ -29,7 +29,7 @@ typedef struct
 
 /*
  * Forms unions of subkeys after page split, but
- * uses only tuples aren't in groups of equalent tuples
+ * uses only tuples that aren't in groups of equivalent tuples
  */
 static void
 gistunionsubkeyvec(GISTSTATE *giststate, IndexTuple *itvec,
@@ -200,8 +200,8 @@ do {	\
 
 /*
  * adjust left and right unions according to splits by previous
- * split by firsts columns. This function is called only in case
- * when pickSplit doesn't support subspplit.
+ * split by first columns. This function is called only in case
+ * when pickSplit doesn't support subsplit.
  */
 
 static void
@@ -503,8 +503,8 @@ gistSplitHalf(GIST_SPLITVEC *v, int len)
 }
 
 /*
- * trys to split page by attno key, in a case of null
- * values move its to separate page.
+ * tries to split page by attno key, in case of null
+ * values move those to separate page.
  */
 void
 gistSplitByKey(Relation r, Page page, IndexTuple *itup, int len, GISTSTATE *giststate,
@@ -531,7 +531,7 @@ gistSplitByKey(Relation r, Page page, IndexTuple *itup, int len, GISTSTATE *gist
 	{
 		/*
 		 * Corner case: All keys in attno column are null, we should try to
-		 * split by keys in next column. It all keys in all columns are NULL
+		 * split by keys in next column. If all keys in all columns are NULL
 		 * just split page half by half
 		 */
 		v->spl_risnull[attno] = v->spl_lisnull[attno] = TRUE;
@@ -582,7 +582,7 @@ gistSplitByKey(Relation r, Page page, IndexTuple *itup, int len, GISTSTATE *gist
 			{
 				/*
 				 * simple case: left and right keys for attno column are
-				 * equial
+				 * equal
 				 */
 				gistSplitByKey(r, page, itup, len, giststate, v, entryvec, attno + 1);
 			}

src/backend/access/gist/gistutil.c

@@ -22,7 +22,7 @@
 #include "utils/builtins.h"
 
 /*
- * static *S used for temrorary storage (saves stack and palloc() call)
+ * static *S used for temporary storage (saves stack and palloc() call)
  */
 
 static Datum attrS[INDEX_MAX_KEYS];
@@ -148,8 +148,8 @@ gistfillitupvec(IndexTuple *vec, int veclen, int *memlen)
 }
 
 /*
- * Make unions of keys in IndexTuple vector, return FALSE if itvec contains
- * invalid tuple. Resulting Datums aren't compressed.
+ * Make unions of keys in IndexTuple vector.
+ * Resulting Datums aren't compressed.
  */
 
 void

src/backend/access/gist/gistvacuum.c

@@ -131,7 +131,7 @@ pushStackIfSplited(Page page, GistBDItem *stack)
 
 /*
  * Bulk deletion of all index entries pointing to a set of heap tuples and
- * check invalid tuples after crash recovery.
+ * check invalid tuples left after upgrade.
  * The set of target tuples is specified via a callback routine that tells
  * whether any given heap tuple (identified by ItemPointer) is being deleted.
  *

src/backend/access/transam/clog.c

@@ -44,9 +44,10 @@
  *
  * Note: because TransactionIds are 32 bits and wrap around at 0xFFFFFFFF,
  * CLOG page numbering also wraps around at 0xFFFFFFFF/CLOG_XACTS_PER_PAGE,
- * and CLOG segment numbering at 0xFFFFFFFF/CLOG_XACTS_PER_SEGMENT.  We need
- * take no explicit notice of that fact in this module, except when comparing
- * segment and page numbers in TruncateCLOG (see CLOGPagePrecedes).
+ * and CLOG segment numbering at
+ * 0xFFFFFFFF/CLOG_XACTS_PER_PAGE/SLRU_PAGES_PER_SEGMENT.  We need take no
+ * explicit notice of that fact in this module, except when comparing segment
+ * and page numbers in TruncateCLOG (see CLOGPagePrecedes).
  */
 
 /* We need two bits per xact, so four xacts fit in a byte */

src/backend/access/transam/slru.c

@@ -280,6 +280,8 @@ SimpleLruZeroPage(SlruCtl ctl, int pageno)
  * in a page from disk into an existing buffer.  (Such an old page cannot
  * have any interesting LSNs, since we'd have flushed them before writing
  * the page in the first place.)
+ *
+ * This assumes that InvalidXLogRecPtr is bitwise-all-0.
  */
 static void
 SimpleLruZeroLSNs(SlruCtl ctl, int slotno)

src/backend/executor/nodeWindowAgg.c

@@ -1668,7 +1668,7 @@ ExecEndWindowAgg(WindowAggState *node)
 }
 
 /* -----------------
- * ExecRescanWindowAgg
+ * ExecReScanWindowAgg
  * -----------------
  */
 void

src/backend/storage/ipc/procarray.c

@@ -1214,7 +1214,7 @@ GetMaxSnapshotSubxidCount(void)
  *
  * We also update the following backend-global variables:
  *		TransactionXmin: the oldest xmin of any snapshot in use in the
- *			current transaction (this is the same as MyProc->xmin).
+ *			current transaction (this is the same as MyPgXact->xmin).
  *		RecentXmin: the xmin computed for the most recent snapshot.  XIDs
  *			older than this are known not running any more.
  *		RecentGlobalXmin: the global xmin (oldest TransactionXmin across all

src/backend/utils/hash/hashfn.c

@@ -25,7 +25,7 @@
 
 
 /*
- * string_hash: hash function for keys that are null-terminated strings.
+ * string_hash: hash function for keys that are NUL-terminated strings.
  *
  * NOTE: this is the default hash function if none is specified.
  */

src/include/access/gist.h

@@ -89,7 +89,7 @@ typedef GISTPageOpaqueData *GISTPageOpaque;
  * that corresponding spl_(r|l)datum already defined and
  * PickSplit should use that value. PickSplit should always set
  * spl_(r|l)datum_exists to false: GiST will check value to
- * control supportng this feature by PickSplit...
+ * control supporting this feature by PickSplit...
  */
 typedef struct GIST_SPLITVEC
 {