diff --git a/src/backend/utils/mmgr/aset.c b/src/backend/utils/mmgr/aset.c
index ec3e264a73..8d6d804025 100644
--- a/src/backend/utils/mmgr/aset.c
+++ b/src/backend/utils/mmgr/aset.c
@@ -150,11 +150,13 @@ typedef AllocSetContext *AllocSet;
  */
 typedef struct AllocBlockData
 {
-	AllocSet	aset;			/* aset that owns this block */
 	AllocBlock	prev;			/* prev block in aset's blocks list, if any */
 	AllocBlock	next;			/* next block in aset's blocks list, if any */
 	char	   *freeptr;		/* start of free space in this block */
 	char	   *endptr;			/* end of space in this block */
+#ifdef MEMORY_CONTEXT_CHECKING
+	AllocSet	aset;			/* aset that owns this block */
+#endif	
 }			AllocBlockData;
 
 /*
@@ -467,7 +469,7 @@ AllocSetContextCreateInternal(MemoryContext parent,
 	 * the context header and its block header follows that.
 	 */
 	set = (AllocSet) malloc(firstBlockSize);
-	if (set == NULL)
+	if (unlikely(set == NULL))
 	{
 		if (TopMemoryContext)
 			MemoryContextStats(TopMemoryContext);
@@ -485,11 +487,13 @@ AllocSetContextCreateInternal(MemoryContext parent,
 
 	/* Fill in the initial block's block header */
 	block = (AllocBlock) (((char *) set) + MAXALIGN(sizeof(AllocSetContext)));
-	block->aset = set;
 	block->freeptr = ((char *) block) + ALLOC_BLOCKHDRSZ;
 	block->endptr = ((char *) set) + firstBlockSize;
 	block->prev = NULL;
 	block->next = NULL;
+#ifdef MEMORY_CONTEXT_CHECKING
+	block->aset = set;
+#endif
 
 	/* Mark unallocated space NOACCESS; leave the block header alone. */
 	VALGRIND_MAKE_MEM_NOACCESS(block->freeptr, block->endptr - block->freeptr);
@@ -738,17 +742,18 @@ AllocSetAlloc(MemoryContext context, Size size)
 		chunk_size = MAXALIGN(size);
 		blksize = chunk_size + ALLOC_BLOCKHDRSZ + ALLOC_CHUNKHDRSZ;
 		block = (AllocBlock) malloc(blksize);
-		if (block == NULL)
+		if (unlikely(block == NULL))
 			return NULL;
 
-		context->mem_allocated += blksize;
-
-		block->aset = set;
 		block->freeptr = block->endptr = ((char *) block) + blksize;
+#ifdef MEMORY_CONTEXT_CHECKING
+		block->aset = set;
+#endif
 
 		chunk = (AllocChunk) (((char *) block) + ALLOC_BLOCKHDRSZ);
-		chunk->aset = set;
 		chunk->size = chunk_size;
+		chunk->aset = set;
+
 #ifdef MEMORY_CONTEXT_CHECKING
 		chunk->requested_size = size;
 		/* set mark to catch clobber of "unused" space */
@@ -779,6 +784,8 @@ AllocSetAlloc(MemoryContext context, Size size)
 			set->blocks = block;
 		}
 
+		context->mem_allocated += blksize;
+
 		/* Ensure any padding bytes are marked NOACCESS. */
 		VALGRIND_MAKE_MEM_NOACCESS((char *) AllocChunkGetPointer(chunk) + size,
 								   chunk_size - size);
@@ -931,14 +938,14 @@ AllocSetAlloc(MemoryContext context, Size size)
 			block = (AllocBlock) malloc(blksize);
 		}
 
-		if (block == NULL)
+		if (unlikely(block == NULL))
 			return NULL;
 
-		context->mem_allocated += blksize;
-
-		block->aset = set;
 		block->freeptr = ((char *) block) + ALLOC_BLOCKHDRSZ;
 		block->endptr = ((char *) block) + blksize;
+#ifdef MEMORY_CONTEXT_CHECKING
+		block->aset = set;
+#endif
 
 		/* Mark unallocated space NOACCESS. */
 		VALGRIND_MAKE_MEM_NOACCESS(block->freeptr,
@@ -948,7 +955,9 @@ AllocSetAlloc(MemoryContext context, Size size)
 		block->next = set->blocks;
 		if (block->next)
 			block->next->prev = block;
+
 		set->blocks = block;
+		context->mem_allocated += blksize;
 	}
 
 	/*
@@ -964,6 +973,7 @@ AllocSetAlloc(MemoryContext context, Size size)
 
 	chunk->aset = (void *) set;
 	chunk->size = chunk_size;
+
 #ifdef MEMORY_CONTEXT_CHECKING
 	chunk->requested_size = size;
 	/* set mark to catch clobber of "unused" space */
@@ -1019,8 +1029,7 @@ AllocSetFree(MemoryContext context, void *pointer)
 		 * reference the correct aset, and freeptr and endptr should point
 		 * just past the chunk.
 		 */
-		if (block->aset != set ||
-			block->freeptr != block->endptr ||
+		if (block->freeptr != block->endptr ||
 			block->freeptr != ((char *) block) +
 			(chunk->size + ALLOC_BLOCKHDRSZ + ALLOC_CHUNKHDRSZ))
 			elog(ERROR, "could not find block containing chunk %p", chunk);
@@ -1108,8 +1117,7 @@ AllocSetRealloc(MemoryContext context, void *pointer, Size size)
 		 * reference the correct aset, and freeptr and endptr should point
 		 * just past the chunk.
 		 */
-		if (block->aset != set ||
-			block->freeptr != block->endptr ||
+		if (block->freeptr != block->endptr ||
 			block->freeptr != ((char *) block) +
 			(oldsize + ALLOC_BLOCKHDRSZ + ALLOC_CHUNKHDRSZ))
 			elog(ERROR, "could not find block containing chunk %p", chunk);
@@ -1128,17 +1136,13 @@ AllocSetRealloc(MemoryContext context, void *pointer, Size size)
 		oldblksize = block->endptr - ((char *) block);
 
 		block = (AllocBlock) realloc(block, blksize);
-		if (block == NULL)
+		if (unlikely(block == NULL))
 		{
 			/* Disallow external access to private part of chunk header. */
 			VALGRIND_MAKE_MEM_NOACCESS(chunk, ALLOCCHUNK_PRIVATE_LEN);
 			return NULL;
 		}
 
-		/* updated separately, not to underflow when (oldblksize > blksize) */
-		context->mem_allocated -= oldblksize;
-		context->mem_allocated += blksize;
-
 		block->freeptr = block->endptr = ((char *) block) + blksize;
 
 		/* Update pointers since block has likely been moved */
@@ -1186,6 +1190,10 @@ AllocSetRealloc(MemoryContext context, void *pointer, Size size)
 		VALGRIND_MAKE_MEM_DEFINED(pointer, oldsize);
 #endif
 
+		/* updated separately, not to underflow when (oldblksize > blksize) */
+		context->mem_allocated -= oldblksize;
+		context->mem_allocated += blksize;
+
 		/* Ensure any padding bytes are marked NOACCESS. */
 		VALGRIND_MAKE_MEM_NOACCESS((char *) pointer + size, chksize - size);
 
@@ -1263,7 +1271,7 @@ AllocSetRealloc(MemoryContext context, void *pointer, Size size)
 		newPointer = AllocSetAlloc((MemoryContext) set, size);
 
 		/* leave immediately if request was not completed */
-		if (newPointer == NULL)
+		if (unlikely(newPointer == NULL))
 		{
 			/* Disallow external access to private part of chunk header. */
 			VALGRIND_MAKE_MEM_NOACCESS(chunk, ALLOCCHUNK_PRIVATE_LEN);