updated location of predicatelockpage

Author: shubhambaraiss

src/rumget.c

@@ -197,10 +197,10 @@ scanPostingTree(Relation index, RumScanEntry scanEntry,
 
 	buffer = rumScanBeginPostingTree(gdi, NULL);
 
-	PredicateLockPage(index, BufferGetBlockNumber(buffer), snapshot);
-
 	IncrBufferRefCount(buffer); /* prevent unpin in freeRumBtreeStack */
 
+	PredicateLockPage(index, BufferGetBlockNumber(buffer), snapshot);
+
 	freeRumBtreeStack(gdi->stack);
 	pfree(gdi);
 
@@ -1707,15 +1707,15 @@ entryFindItem(RumState * rumstate, RumScanEntry entry, RumItem * item, Snapshot
 								RUM_SHARE, entry->scanDirection);
 		entry->gdi->stack->buffer = entry->buffer;
 
-		PredicateLockPage(rumstate->index, BufferGetBlockNumber(entry->buffer), snapshot);
-
 		if (entry->buffer == InvalidBuffer)
 		{
 			ItemPointerSetInvalid(&entry->curItem.iptr);
 			entry->isFinished = TRUE;
 			return;
 		}
 
+		PredicateLockPage(rumstate->index, BufferGetBlockNumber(entry->buffer), snapshot);
+
 		entry->gdi->stack->blkno = BufferGetBlockNumber(entry->buffer);
 
 		if (scanPage(rumstate, entry, item, true))