Fix inconsistencies and typos in the tree, take 9

This addresses more issues with code comments, variable names and
unreferenced variables.

Author: Alexander Lakhin
Discussion: https://postgr.es/m/7ab243e0-116d-3e44-d120-76b3df7abefd@gmail.com

src/backend/access/gin/README

@@ -270,7 +270,7 @@ is stored in the higher bits. That requires 43 bits in total, which
 conveniently fits in at most 6 bytes.
 
 A compressed posting list is passed around and stored on disk in a
-PackedPostingList struct. The first item in the list is stored uncompressed
+GinPostingList struct. The first item in the list is stored uncompressed
 as a regular ItemPointerData, followed by the length of the list in bytes,
 followed by the packed items.
 

src/backend/access/gin/ginbtree.c

@@ -650,7 +650,7 @@ ginPlaceToPage(GinBtree btree, GinBtreeStack *stack,
 	}
 	else
 	{
-		elog(ERROR, "invalid return code from GIN placeToPage method: %d", rc);
+		elog(ERROR, "invalid return code from GIN beginPlaceToPage method: %d", rc);
 		result = false;			/* keep compiler quiet */
 	}
 

src/backend/access/gist/gistget.c

@@ -74,7 +74,7 @@ gistkillitems(IndexScanDesc scan)
 
 	/*
 	 * Mark all killedItems as dead. We need no additional recheck, because,
-	 * if page was modified, pageLSN must have changed.
+	 * if page was modified, curPageLSN must have changed.
 	 */
 	for (i = 0; i < so->numKilled; i++)
 	{
@@ -379,11 +379,11 @@ gistScanPage(IndexScanDesc scan, GISTSearchItem *pageItem, double *myDistances,
 
 	/*
 	 * Check if the page was deleted after we saw the downlink. There's
-	 * nothing of interest on a deleted page. Note that we must do this
-	 * after checking the NSN for concurrent splits! It's possible that
-	 * the page originally contained some tuples that are visible to us,
-	 * but was split so that all the visible tuples were moved to another
-	 * page, and then this page was deleted.
+	 * nothing of interest on a deleted page. Note that we must do this after
+	 * checking the NSN for concurrent splits! It's possible that the page
+	 * originally contained some tuples that are visible to us, but was split
+	 * so that all the visible tuples were moved to another page, and then
+	 * this page was deleted.
 	 */
 	if (GistPageIsDeleted(page))
 	{

src/backend/access/hash/hash_xlog.c

@@ -706,7 +706,7 @@ hash_xlog_squeeze_page(XLogReaderState *record)
 
 		/*
 		 * if the page on which are adding tuples is a page previous to freed
-		 * overflow page, then update its nextblno.
+		 * overflow page, then update its nextblkno.
 		 */
 		if (xldata->is_prev_bucket_same_wrt)
 		{

src/backend/access/hash/hashinsert.c

@@ -257,8 +257,8 @@ restart_insert:
  *	_hash_pgaddtup() -- add a tuple to a particular page in the index.
  *
  * This routine adds the tuple to the page as requested; it does not write out
- * the page.  It is an error to call pgaddtup() without pin and write lock on
- * the target buffer.
+ * the page.  It is an error to call this function without pin and write lock
+ * on the target buffer.
  *
  * Returns the offset number at which the tuple was inserted.  This function
  * is responsible for preserving the condition that tuples in a hash index

src/backend/access/heap/heapam.c

@@ -74,7 +74,7 @@ static HeapTuple heap_prepare_insert(Relation relation, HeapTuple tup,
 									 TransactionId xid, CommandId cid, int options);
 static XLogRecPtr log_heap_update(Relation reln, Buffer oldbuf,
 								  Buffer newbuf, HeapTuple oldtup,
-								  HeapTuple newtup, HeapTuple old_key_tup,
+								  HeapTuple newtup, HeapTuple old_key_tuple,
 								  bool all_visible_cleared, bool new_all_visible_cleared);
 static Bitmapset *HeapDetermineModifiedColumns(Relation relation,
 											   Bitmapset *interesting_cols,

src/backend/access/heap/visibilitymap.c

@@ -124,7 +124,7 @@
 
 /* prototypes for internal routines */
 static Buffer vm_readbuf(Relation rel, BlockNumber blkno, bool extend);
-static void vm_extend(Relation rel, BlockNumber nvmblocks);
+static void vm_extend(Relation rel, BlockNumber vm_nblocks);
 
 
 /*

src/backend/access/nbtree/nbtsort.c

@@ -657,7 +657,7 @@ _bt_blwritepage(BTWriteState *wstate, Page page, BlockNumber blkno)
 	/* XLOG stuff */
 	if (wstate->btws_use_wal)
 	{
-		/* We use the heap NEWPAGE record type for this */
+		/* We use the XLOG_FPI record type for this */
 		log_newpage(&wstate->index->rd_node, MAIN_FORKNUM, blkno, page, true);
 	}
 

src/backend/access/transam/README

@@ -530,7 +530,7 @@ void XLogResetInsertion(void)
     construction workspace.  This is only needed if you have already called
     XLogBeginInsert(), but decide to not insert the record after all.
 
-void XLogEnsureRecordSpace(int max_block_id, int nrdatas)
+void XLogEnsureRecordSpace(int max_block_id, int ndatas)
 
     Normally, the WAL record construction buffers have the following limits:
 

src/backend/access/transam/clog.c

@@ -92,7 +92,7 @@ static int	ZeroCLOGPage(int pageno, bool writeXlog);
 static bool CLOGPagePrecedes(int page1, int page2);
 static void WriteZeroPageXlogRec(int pageno);
 static void WriteTruncateXlogRec(int pageno, TransactionId oldestXact,
-								 Oid oldestXidDb);
+								 Oid oldestXactDb);
 static void TransactionIdSetPageStatus(TransactionId xid, int nsubxids,
 									   TransactionId *subxids, XidStatus status,
 									   XLogRecPtr lsn, int pageno,

src/backend/access/transam/multixact.c

@@ -282,7 +282,7 @@ typedef struct MultiXactStateData
 } MultiXactStateData;
 
 /*
- * Last element of OldestMemberMXactID and OldestVisibleMXactId arrays.
+ * Last element of OldestMemberMXactId and OldestVisibleMXactId arrays.
  * Valid elements are (1..MaxOldestSlot); element 0 is never used.
  */
 #define MaxOldestSlot	(MaxBackends + max_prepared_xacts)