diff --git a/src/ivfkmeans.c b/src/ivfkmeans.c
index d4130f7..548f7ff 100644
--- a/src/ivfkmeans.c
+++ b/src/ivfkmeans.c
@@ -254,50 +254,58 @@ ShowMemoryUsage(MemoryContext context, Size estimatedSize)
 }
 #endif
 
+static void
+VectorSumCenter(const void *v, Vector * aggCenter)
+{
+	Vector	   *vec = (Vector *) v;
+
+	for (int k = 0; k < aggCenter->dim; k++)
+		aggCenter->x[k] += vec->x[k];
+}
+
+static void
+HalfvecSumCenter(const void *v, Vector * aggCenter)
+{
+	HalfVector *vec = (HalfVector *) v;
+
+	for (int k = 0; k < aggCenter->dim; k++)
+		aggCenter->x[k] += HalfToFloat4(vec->x[k]);
+}
+
+static void
+BitSumCenter(const void *v, Vector * aggCenter)
+{
+	VarBit	   *vec = (VarBit *) v;
+
+	for (int k = 0; k < aggCenter->dim; k++)
+		aggCenter->x[k] += (float) (((VARBITS(vec)[k / 8]) >> (7 - (k % 8))) & 0x01);
+}
+
 /*
  * Sum centers
  */
 static void
 SumCenters(VectorArray samples, VectorArray aggCenters, int *closestCenters, IvfflatType type)
 {
-	int			dimensions = aggCenters->dim;
 	int			numSamples = samples->length;
+	void		(*sumCenter) (const void *v, Vector * aggCenter);
 
 	if (type == IVFFLAT_TYPE_VECTOR)
-	{
-		for (int j = 0; j < numSamples; j++)
-		{
-			Vector	   *aggCenter = (Vector *) VectorArrayGet(aggCenters, closestCenters[j]);
-			Vector	   *vec = (Vector *) VectorArrayGet(samples, j);
-
-			for (int k = 0; k < dimensions; k++)
-				aggCenter->x[k] += vec->x[k];
-		}
-	}
+		sumCenter = VectorSumCenter;
 	else if (type == IVFFLAT_TYPE_HALFVEC)
-	{
-		for (int j = 0; j < numSamples; j++)
-		{
-			Vector	   *aggCenter = (Vector *) VectorArrayGet(aggCenters, closestCenters[j]);
-			HalfVector *vec = (HalfVector *) VectorArrayGet(samples, j);
-
-			for (int k = 0; k < dimensions; k++)
-				aggCenter->x[k] += HalfToFloat4(vec->x[k]);
-		}
-	}
+		sumCenter = HalfvecSumCenter;
 	else if (type == IVFFLAT_TYPE_BIT)
-	{
-		for (int j = 0; j < numSamples; j++)
-		{
-			Vector	   *aggCenter = (Vector *) VectorArrayGet(aggCenters, closestCenters[j]);
-			VarBit	   *vec = (VarBit *) VectorArrayGet(samples, j);
-
-			for (int k = 0; k < dimensions; k++)
-				aggCenter->x[k] += (float) (((VARBITS(vec)[k / 8]) >> (7 - (k % 8))) & 0x01);
-		}
-	}
+		sumCenter = BitSumCenter;
 	else
 		elog(ERROR, "Unsupported type");
+
+
+	for (int j = 0; j < numSamples; j++)
+	{
+		Vector	   *aggCenter = (Vector *) VectorArrayGet(aggCenters, closestCenters[j]);
+
+		sumCenter(VectorArrayGet(samples, j), aggCenter);
+	}
 }
 
 /*